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gerrit.openfyde.cn / chromium.googlesource.com / chromium / deps / sqlite / refs/heads/upstream/unhex-function / . / src / select.c
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/*
** 2001 September 15
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
*/
#include "sqliteInt.h"
/*
** An instance of the following object is used to record information about
** how to process the DISTINCT keyword, to simplify passing that information
** into the selectInnerLoop() routine.
*/
typedef struct DistinctCtx DistinctCtx;
struct DistinctCtx {
u8 isTnct; /* 0: Not distinct. 1: DISTICT 2: DISTINCT and ORDER BY */
u8 eTnctType; /* One of the WHERE_DISTINCT_* operators */
int tabTnct; /* Ephemeral table used for DISTINCT processing */
int addrTnct; /* Address of OP_OpenEphemeral opcode for tabTnct */
};
/*
** An instance of the following object is used to record information about
** the ORDER BY (or GROUP BY) clause of query is being coded.
**
** The aDefer[] array is used by the sorter-references optimization. For
** example, assuming there is no index that can be used for the ORDER BY,
** for the query:
**
** SELECT a, bigblob FROM t1 ORDER BY a LIMIT 10;
**
** it may be more efficient to add just the "a" values to the sorter, and
** retrieve the associated "bigblob" values directly from table t1 as the
** 10 smallest "a" values are extracted from the sorter.
**
** When the sorter-reference optimization is used, there is one entry in the
** aDefer[] array for each database table that may be read as values are
** extracted from the sorter.
*/
typedef struct SortCtx SortCtx;
struct SortCtx {
ExprList *pOrderBy; /* The ORDER BY (or GROUP BY clause) */
int nOBSat; /* Number of ORDER BY terms satisfied by indices */
int iECursor; /* Cursor number for the sorter */
int regReturn; /* Register holding block-output return address */
int labelBkOut; /* Start label for the block-output subroutine */
int addrSortIndex; /* Address of the OP_SorterOpen or OP_OpenEphemeral */
int labelDone; /* Jump here when done, ex: LIMIT reached */
int labelOBLopt; /* Jump here when sorter is full */
u8 sortFlags; /* Zero or more SORTFLAG_* bits */
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
u8 nDefer; /* Number of valid entries in aDefer[] */
struct DeferredCsr {
Table *pTab; /* Table definition */
int iCsr; /* Cursor number for table */
int nKey; /* Number of PK columns for table pTab (>=1) */
} aDefer[4];
#endif
struct RowLoadInfo *pDeferredRowLoad; /* Deferred row loading info or NULL */
#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
int addrPush; /* First instruction to push data into sorter */
int addrPushEnd; /* Last instruction that pushes data into sorter */
#endif
};
#define SORTFLAG_UseSorter 0x01 /* Use SorterOpen instead of OpenEphemeral */
/*
** Delete all the content of a Select structure. Deallocate the structure
** itself depending on the value of bFree
**
** If bFree==1, call sqlite3DbFree() on the p object.
** If bFree==0, Leave the first Select object unfreed
*/
static void clearSelect(sqlite3 *db, Select *p, int bFree){
assert( db!=0 );
while( p ){
Select *pPrior = p->pPrior;
sqlite3ExprListDelete(db, p->pEList);
sqlite3SrcListDelete(db, p->pSrc);
sqlite3ExprDelete(db, p->pWhere);
sqlite3ExprListDelete(db, p->pGroupBy);
sqlite3ExprDelete(db, p->pHaving);
sqlite3ExprListDelete(db, p->pOrderBy);
sqlite3ExprDelete(db, p->pLimit);
if( OK_IF_ALWAYS_TRUE(p->pWith) ) sqlite3WithDelete(db, p->pWith);
#ifndef SQLITE_OMIT_WINDOWFUNC
if( OK_IF_ALWAYS_TRUE(p->pWinDefn) ){
sqlite3WindowListDelete(db, p->pWinDefn);
}
while( p->pWin ){
assert( p->pWin->ppThis==&p->pWin );
sqlite3WindowUnlinkFromSelect(p->pWin);
}
#endif
if( bFree ) sqlite3DbNNFreeNN(db, p);
p = pPrior;
bFree = 1;
}
}
/*
** Initialize a SelectDest structure.
*/
void sqlite3SelectDestInit(SelectDest *pDest, int eDest, int iParm){
pDest->eDest = (u8)eDest;
pDest->iSDParm = iParm;
pDest->iSDParm2 = 0;
pDest->zAffSdst = 0;
pDest->iSdst = 0;
pDest->nSdst = 0;
}
/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/
Select *sqlite3SelectNew(
Parse *pParse, /* Parsing context */
ExprList *pEList, /* which columns to include in the result */
SrcList *pSrc, /* the FROM clause -- which tables to scan */
Expr *pWhere, /* the WHERE clause */
ExprList *pGroupBy, /* the GROUP BY clause */
Expr *pHaving, /* the HAVING clause */
ExprList *pOrderBy, /* the ORDER BY clause */
u32 selFlags, /* Flag parameters, such as SF_Distinct */
Expr *pLimit /* LIMIT value. NULL means not used */
){
Select *pNew, *pAllocated;
Select standin;
pAllocated = pNew = sqlite3DbMallocRawNN(pParse->db, sizeof(*pNew) );
if( pNew==0 ){
assert( pParse->db->mallocFailed );
pNew = &standin;
}
if( pEList==0 ){
pEList = sqlite3ExprListAppend(pParse, 0,
sqlite3Expr(pParse->db,TK_ASTERISK,0));
}
pNew->pEList = pEList;
pNew->op = TK_SELECT;
pNew->selFlags = selFlags;
pNew->iLimit = 0;
pNew->iOffset = 0;
pNew->selId = ++pParse->nSelect;
pNew->addrOpenEphm[0] = -1;
pNew->addrOpenEphm[1] = -1;
pNew->nSelectRow = 0;
if( pSrc==0 ) pSrc = sqlite3DbMallocZero(pParse->db, sizeof(*pSrc));
pNew->pSrc = pSrc;
pNew->pWhere = pWhere;
pNew->pGroupBy = pGroupBy;
pNew->pHaving = pHaving;
pNew->pOrderBy = pOrderBy;
pNew->pPrior = 0;
pNew->pNext = 0;
pNew->pLimit = pLimit;
pNew->pWith = 0;
#ifndef SQLITE_OMIT_WINDOWFUNC
pNew->pWin = 0;
pNew->pWinDefn = 0;
#endif
if( pParse->db->mallocFailed ) {
clearSelect(pParse->db, pNew, pNew!=&standin);
pAllocated = 0;
}else{
assert( pNew->pSrc!=0 || pParse->nErr>0 );
}
return pAllocated;
}
/*
** Delete the given Select structure and all of its substructures.
*/
void sqlite3SelectDelete(sqlite3 *db, Select *p){
if( OK_IF_ALWAYS_TRUE(p) ) clearSelect(db, p, 1);
}
/*
** Return a pointer to the right-most SELECT statement in a compound.
*/
static Select *findRightmost(Select *p){
while( p->pNext ) p = p->pNext;
return p;
}
/*
** Given 1 to 3 identifiers preceding the JOIN keyword, determine the
** type of join. Return an integer constant that expresses that type
** in terms of the following bit values:
**
** JT_INNER
** JT_CROSS
** JT_OUTER
** JT_NATURAL
** JT_LEFT
** JT_RIGHT
**
** A full outer join is the combination of JT_LEFT and JT_RIGHT.
**
** If an illegal or unsupported join type is seen, then still return
** a join type, but put an error in the pParse structure.
**
** These are the valid join types:
**
**
** pA pB pC Return Value
** ------- ----- ----- ------------
** CROSS - - JT_CROSS
** INNER - - JT_INNER
** LEFT - - JT_LEFT|JT_OUTER
** LEFT OUTER - JT_LEFT|JT_OUTER
** RIGHT - - JT_RIGHT|JT_OUTER
** RIGHT OUTER - JT_RIGHT|JT_OUTER
** FULL - - JT_LEFT|JT_RIGHT|JT_OUTER
** FULL OUTER - JT_LEFT|JT_RIGHT|JT_OUTER
** NATURAL INNER - JT_NATURAL|JT_INNER
** NATURAL LEFT - JT_NATURAL|JT_LEFT|JT_OUTER
** NATURAL LEFT OUTER JT_NATURAL|JT_LEFT|JT_OUTER
** NATURAL RIGHT - JT_NATURAL|JT_RIGHT|JT_OUTER
** NATURAL RIGHT OUTER JT_NATURAL|JT_RIGHT|JT_OUTER
** NATURAL FULL - JT_NATURAL|JT_LEFT|JT_RIGHT
** NATURAL FULL OUTER JT_NATRUAL|JT_LEFT|JT_RIGHT
**
** To preserve historical compatibly, SQLite also accepts a variety
** of other non-standard and in many cases non-sensical join types.
** This routine makes as much sense at it can from the nonsense join
** type and returns a result. Examples of accepted nonsense join types
** include but are not limited to:
**
** INNER CROSS JOIN -> same as JOIN
** NATURAL CROSS JOIN -> same as NATURAL JOIN
** OUTER LEFT JOIN -> same as LEFT JOIN
** LEFT NATURAL JOIN -> same as NATURAL LEFT JOIN
** LEFT RIGHT JOIN -> same as FULL JOIN
** RIGHT OUTER FULL JOIN -> same as FULL JOIN
** CROSS CROSS CROSS JOIN -> same as JOIN
**
** The only restrictions on the join type name are:
**
** * "INNER" cannot appear together with "OUTER", "LEFT", "RIGHT",
** or "FULL".
**
** * "CROSS" cannot appear together with "OUTER", "LEFT", "RIGHT,
** or "FULL".
**
** * If "OUTER" is present then there must also be one of
** "LEFT", "RIGHT", or "FULL"
*/
int sqlite3JoinType(Parse *pParse, Token *pA, Token *pB, Token *pC){
int jointype = 0;
Token *apAll[3];
Token *p;
/* 0123456789 123456789 123456789 123 */
static const char zKeyText[] = "naturaleftouterightfullinnercross";
static const struct {
u8 i; /* Beginning of keyword text in zKeyText[] */
u8 nChar; /* Length of the keyword in characters */
u8 code; /* Join type mask */
} aKeyword[] = {
/* (0) natural */ { 0, 7, JT_NATURAL },
/* (1) left */ { 6, 4, JT_LEFT|JT_OUTER },
/* (2) outer */ { 10, 5, JT_OUTER },
/* (3) right */ { 14, 5, JT_RIGHT|JT_OUTER },
/* (4) full */ { 19, 4, JT_LEFT|JT_RIGHT|JT_OUTER },
/* (5) inner */ { 23, 5, JT_INNER },
/* (6) cross */ { 28, 5, JT_INNER|JT_CROSS },
};
int i, j;
apAll[0] = pA;
apAll[1] = pB;
apAll[2] = pC;
for(i=0; i<3 && apAll[i]; i++){
p = apAll[i];
for(j=0; j<ArraySize(aKeyword); j++){
if( p->n==aKeyword[j].nChar
&& sqlite3StrNICmp((char*)p->z, &zKeyText[aKeyword[j].i], p->n)==0 ){
jointype |= aKeyword[j].code;
break;
}
}
testcase( j==0 || j==1 || j==2 || j==3 || j==4 || j==5 || j==6 );
if( j>=ArraySize(aKeyword) ){
jointype |= JT_ERROR;
break;
}
}
if(
(jointype & (JT_INNER|JT_OUTER))==(JT_INNER|JT_OUTER) ||
(jointype & JT_ERROR)!=0 ||
(jointype & (JT_OUTER|JT_LEFT|JT_RIGHT))==JT_OUTER
){
const char *zSp1 = " ";
const char *zSp2 = " ";
if( pB==0 ){ zSp1++; }
if( pC==0 ){ zSp2++; }
sqlite3ErrorMsg(pParse, "unknown join type: "
"%T%s%T%s%T", pA, zSp1, pB, zSp2, pC);
jointype = JT_INNER;
}
return jointype;
}
/*
** Return the index of a column in a table. Return -1 if the column
** is not contained in the table.
*/
int sqlite3ColumnIndex(Table *pTab, const char *zCol){
int i;
u8 h = sqlite3StrIHash(zCol);
Column *pCol;
for(pCol=pTab->aCol, i=0; i<pTab->nCol; pCol++, i++){
if( pCol->hName==h && sqlite3StrICmp(pCol->zCnName, zCol)==0 ) return i;
}
return -1;
}
/*
** Mark a subquery result column as having been used.
*/
void sqlite3SrcItemColumnUsed(SrcItem *pItem, int iCol){
assert( pItem!=0 );
assert( (int)pItem->fg.isNestedFrom == IsNestedFrom(pItem->pSelect) );
if( pItem->fg.isNestedFrom ){
ExprList *pResults;
assert( pItem->pSelect!=0 );
pResults = pItem->pSelect->pEList;
assert( pResults!=0 );
assert( iCol>=0 && iCol<pResults->nExpr );
pResults->a[iCol].fg.bUsed = 1;
}
}
/*
** Search the tables iStart..iEnd (inclusive) in pSrc, looking for a
** table that has a column named zCol. The search is left-to-right.
** The first match found is returned.
**
** When found, set *piTab and *piCol to the table index and column index
** of the matching column and return TRUE.
**
** If not found, return FALSE.
*/
static int tableAndColumnIndex(
SrcList *pSrc, /* Array of tables to search */
int iStart, /* First member of pSrc->a[] to check */
int iEnd, /* Last member of pSrc->a[] to check */
const char *zCol, /* Name of the column we are looking for */
int *piTab, /* Write index of pSrc->a[] here */
int *piCol, /* Write index of pSrc->a[*piTab].pTab->aCol[] here */
int bIgnoreHidden /* Ignore hidden columns */
){
int i; /* For looping over tables in pSrc */
int iCol; /* Index of column matching zCol */
assert( iEnd<pSrc->nSrc );
assert( iStart>=0 );
assert( (piTab==0)==(piCol==0) ); /* Both or neither are NULL */
for(i=iStart; i<=iEnd; i++){
iCol = sqlite3ColumnIndex(pSrc->a[i].pTab, zCol);
if( iCol>=0
&& (bIgnoreHidden==0 || IsHiddenColumn(&pSrc->a[i].pTab->aCol[iCol])==0)
){
if( piTab ){
sqlite3SrcItemColumnUsed(&pSrc->a[i], iCol);
*piTab = i;
*piCol = iCol;
}
return 1;
}
}
return 0;
}
/*
** Set the EP_OuterON property on all terms of the given expression.
** And set the Expr.w.iJoin to iTable for every term in the
** expression.
**
** The EP_OuterON property is used on terms of an expression to tell
** the OUTER JOIN processing logic that this term is part of the
** join restriction specified in the ON or USING clause and not a part
** of the more general WHERE clause. These terms are moved over to the
** WHERE clause during join processing but we need to remember that they
** originated in the ON or USING clause.
**
** The Expr.w.iJoin tells the WHERE clause processing that the
** expression depends on table w.iJoin even if that table is not
** explicitly mentioned in the expression. That information is needed
** for cases like this:
**
** SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.b AND t1.x=5
**
** The where clause needs to defer the handling of the t1.x=5
** term until after the t2 loop of the join. In that way, a
** NULL t2 row will be inserted whenever t1.x!=5. If we do not
** defer the handling of t1.x=5, it will be processed immediately
** after the t1 loop and rows with t1.x!=5 will never appear in
** the output, which is incorrect.
*/
void sqlite3SetJoinExpr(Expr *p, int iTable, u32 joinFlag){
assert( joinFlag==EP_OuterON || joinFlag==EP_InnerON );
while( p ){
ExprSetProperty(p, joinFlag);
assert( !ExprHasProperty(p, EP_TokenOnly|EP_Reduced) );
ExprSetVVAProperty(p, EP_NoReduce);
p->w.iJoin = iTable;
if( p->op==TK_FUNCTION ){
assert( ExprUseXList(p) );
if( p->x.pList ){
int i;
for(i=0; i<p->x.pList->nExpr; i++){
sqlite3SetJoinExpr(p->x.pList->a[i].pExpr, iTable, joinFlag);
}
}
}
sqlite3SetJoinExpr(p->pLeft, iTable, joinFlag);
p = p->pRight;
}
}
/* Undo the work of sqlite3SetJoinExpr(). This is used when a LEFT JOIN
** is simplified into an ordinary JOIN, and when an ON expression is
** "pushed down" into the WHERE clause of a subquery.
**
** Convert every term that is marked with EP_OuterON and w.iJoin==iTable into
** an ordinary term that omits the EP_OuterON mark. Or if iTable<0, then
** just clear every EP_OuterON and EP_InnerON mark from the expression tree.
**
** If nullable is true, that means that Expr p might evaluate to NULL even
** if it is a reference to a NOT NULL column. This can happen, for example,
** if the table that p references is on the left side of a RIGHT JOIN.
** If nullable is true, then take care to not remove the EP_CanBeNull bit.
** See forum thread https://sqlite.org/forum/forumpost/b40696f50145d21c
*/
static void unsetJoinExpr(Expr *p, int iTable, int nullable){
while( p ){
if( iTable<0 || (ExprHasProperty(p, EP_OuterON) && p->w.iJoin==iTable) ){
ExprClearProperty(p, EP_OuterON|EP_InnerON);
if( iTable>=0 ) ExprSetProperty(p, EP_InnerON);
}
if( p->op==TK_COLUMN && p->iTable==iTable && !nullable ){
ExprClearProperty(p, EP_CanBeNull);
}
if( p->op==TK_FUNCTION ){
assert( ExprUseXList(p) );
if( p->x.pList ){
int i;
for(i=0; i<p->x.pList->nExpr; i++){
unsetJoinExpr(p->x.pList->a[i].pExpr, iTable, nullable);
}
}
}
unsetJoinExpr(p->pLeft, iTable, nullable);
p = p->pRight;
}
}
/*
** This routine processes the join information for a SELECT statement.
**
** * A NATURAL join is converted into a USING join. After that, we
** do not need to be concerned with NATURAL joins and we only have
** think about USING joins.
**
** * ON and USING clauses result in extra terms being added to the
** WHERE clause to enforce the specified constraints. The extra
** WHERE clause terms will be tagged with EP_OuterON or
** EP_InnerON so that we know that they originated in ON/USING.
**
** The terms of a FROM clause are contained in the Select.pSrc structure.
** The left most table is the first entry in Select.pSrc. The right-most
** table is the last entry. The join operator is held in the entry to
** the right. Thus entry 1 contains the join operator for the join between
** entries 0 and 1. Any ON or USING clauses associated with the join are
** also attached to the right entry.
**
** This routine returns the number of errors encountered.
*/
static int sqlite3ProcessJoin(Parse *pParse, Select *p){
SrcList *pSrc; /* All tables in the FROM clause */
int i, j; /* Loop counters */
SrcItem *pLeft; /* Left table being joined */
SrcItem *pRight; /* Right table being joined */
pSrc = p->pSrc;
pLeft = &pSrc->a[0];
pRight = &pLeft[1];
for(i=0; i<pSrc->nSrc-1; i++, pRight++, pLeft++){
Table *pRightTab = pRight->pTab;
u32 joinType;
if( NEVER(pLeft->pTab==0 || pRightTab==0) ) continue;
joinType = (pRight->fg.jointype & JT_OUTER)!=0 ? EP_OuterON : EP_InnerON;
/* If this is a NATURAL join, synthesize an approprate USING clause
** to specify which columns should be joined.
*/
if( pRight->fg.jointype & JT_NATURAL ){
IdList *pUsing = 0;
if( pRight->fg.isUsing || pRight->u3.pOn ){
sqlite3ErrorMsg(pParse, "a NATURAL join may not have "
"an ON or USING clause", 0);
return 1;
}
for(j=0; j<pRightTab->nCol; j++){
char *zName; /* Name of column in the right table */
if( IsHiddenColumn(&pRightTab->aCol[j]) ) continue;
zName = pRightTab->aCol[j].zCnName;
if( tableAndColumnIndex(pSrc, 0, i, zName, 0, 0, 1) ){
pUsing = sqlite3IdListAppend(pParse, pUsing, 0);
if( pUsing ){
assert( pUsing->nId>0 );
assert( pUsing->a[pUsing->nId-1].zName==0 );
pUsing->a[pUsing->nId-1].zName = sqlite3DbStrDup(pParse->db, zName);
}
}
}
if( pUsing ){
pRight->fg.isUsing = 1;
pRight->fg.isSynthUsing = 1;
pRight->u3.pUsing = pUsing;
}
if( pParse->nErr ) return 1;
}
/* Create extra terms on the WHERE clause for each column named
** in the USING clause. Example: If the two tables to be joined are
** A and B and the USING clause names X, Y, and Z, then add this
** to the WHERE clause: A.X=B.X AND A.Y=B.Y AND A.Z=B.Z
** Report an error if any column mentioned in the USING clause is
** not contained in both tables to be joined.
*/
if( pRight->fg.isUsing ){
IdList *pList = pRight->u3.pUsing;
sqlite3 *db = pParse->db;
assert( pList!=0 );
for(j=0; j<pList->nId; j++){
char *zName; /* Name of the term in the USING clause */
int iLeft; /* Table on the left with matching column name */
int iLeftCol; /* Column number of matching column on the left */
int iRightCol; /* Column number of matching column on the right */
Expr *pE1; /* Reference to the column on the LEFT of the join */
Expr *pE2; /* Reference to the column on the RIGHT of the join */
Expr *pEq; /* Equality constraint. pE1 == pE2 */
zName = pList->a[j].zName;
iRightCol = sqlite3ColumnIndex(pRightTab, zName);
if( iRightCol<0
|| tableAndColumnIndex(pSrc, 0, i, zName, &iLeft, &iLeftCol,
pRight->fg.isSynthUsing)==0
){
sqlite3ErrorMsg(pParse, "cannot join using column %s - column "
"not present in both tables", zName);
return 1;
}
pE1 = sqlite3CreateColumnExpr(db, pSrc, iLeft, iLeftCol);
sqlite3SrcItemColumnUsed(&pSrc->a[iLeft], iLeftCol);
if( (pSrc->a[0].fg.jointype & JT_LTORJ)!=0 ){
/* This branch runs if the query contains one or more RIGHT or FULL
** JOINs. If only a single table on the left side of this join
** contains the zName column, then this branch is a no-op.
** But if there are two or more tables on the left side
** of the join, construct a coalesce() function that gathers all
** such tables. Raise an error if more than one of those references
** to zName is not also within a prior USING clause.
**
** We really ought to raise an error if there are two or more
** non-USING references to zName on the left of an INNER or LEFT
** JOIN. But older versions of SQLite do not do that, so we avoid
** adding a new error so as to not break legacy applications.
*/
ExprList *pFuncArgs = 0; /* Arguments to the coalesce() */
static const Token tkCoalesce = { "coalesce", 8 };
while( tableAndColumnIndex(pSrc, iLeft+1, i, zName, &iLeft, &iLeftCol,
pRight->fg.isSynthUsing)!=0 ){
if( pSrc->a[iLeft].fg.isUsing==0
|| sqlite3IdListIndex(pSrc->a[iLeft].u3.pUsing, zName)<0
){
sqlite3ErrorMsg(pParse, "ambiguous reference to %s in USING()",
zName);
break;
}
pFuncArgs = sqlite3ExprListAppend(pParse, pFuncArgs, pE1);
pE1 = sqlite3CreateColumnExpr(db, pSrc, iLeft, iLeftCol);
sqlite3SrcItemColumnUsed(&pSrc->a[iLeft], iLeftCol);
}
if( pFuncArgs ){
pFuncArgs = sqlite3ExprListAppend(pParse, pFuncArgs, pE1);
pE1 = sqlite3ExprFunction(pParse, pFuncArgs, &tkCoalesce, 0);
}
}
pE2 = sqlite3CreateColumnExpr(db, pSrc, i+1, iRightCol);
sqlite3SrcItemColumnUsed(pRight, iRightCol);
pEq = sqlite3PExpr(pParse, TK_EQ, pE1, pE2);
assert( pE2!=0 || pEq==0 );
if( pEq ){
ExprSetProperty(pEq, joinType);
assert( !ExprHasProperty(pEq, EP_TokenOnly|EP_Reduced) );
ExprSetVVAProperty(pEq, EP_NoReduce);
pEq->w.iJoin = pE2->iTable;
}
p->pWhere = sqlite3ExprAnd(pParse, p->pWhere, pEq);
}
}
/* Add the ON clause to the end of the WHERE clause, connected by
** an AND operator.
*/
else if( pRight->u3.pOn ){
sqlite3SetJoinExpr(pRight->u3.pOn, pRight->iCursor, joinType);
p->pWhere = sqlite3ExprAnd(pParse, p->pWhere, pRight->u3.pOn);
pRight->u3.pOn = 0;
pRight->fg.isOn = 1;
}
}
return 0;
}
/*
** An instance of this object holds information (beyond pParse and pSelect)
** needed to load the next result row that is to be added to the sorter.
*/
typedef struct RowLoadInfo RowLoadInfo;
struct RowLoadInfo {
int regResult; /* Store results in array of registers here */
u8 ecelFlags; /* Flag argument to ExprCodeExprList() */
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
ExprList *pExtra; /* Extra columns needed by sorter refs */
int regExtraResult; /* Where to load the extra columns */
#endif
};
/*
** This routine does the work of loading query data into an array of
** registers so that it can be added to the sorter.
*/
static void innerLoopLoadRow(
Parse *pParse, /* Statement under construction */
Select *pSelect, /* The query being coded */
RowLoadInfo *pInfo /* Info needed to complete the row load */
){
sqlite3ExprCodeExprList(pParse, pSelect->pEList, pInfo->regResult,
0, pInfo->ecelFlags);
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
if( pInfo->pExtra ){
sqlite3ExprCodeExprList(pParse, pInfo->pExtra, pInfo->regExtraResult, 0, 0);
sqlite3ExprListDelete(pParse->db, pInfo->pExtra);
}
#endif
}
/*
** Code the OP_MakeRecord instruction that generates the entry to be
** added into the sorter.
**
** Return the register in which the result is stored.
*/
static int makeSorterRecord(
Parse *pParse,
SortCtx *pSort,
Select *pSelect,
int regBase,
int nBase
){
int nOBSat = pSort->nOBSat;
Vdbe *v = pParse->pVdbe;
int regOut = ++pParse->nMem;
if( pSort->pDeferredRowLoad ){
innerLoopLoadRow(pParse, pSelect, pSort->pDeferredRowLoad);
}
sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase+nOBSat, nBase-nOBSat, regOut);
return regOut;
}
/*
** Generate code that will push the record in registers regData
** through regData+nData-1 onto the sorter.
*/
static void pushOntoSorter(
Parse *pParse, /* Parser context */
SortCtx *pSort, /* Information about the ORDER BY clause */
Select *pSelect, /* The whole SELECT statement */
int regData, /* First register holding data to be sorted */
int regOrigData, /* First register holding data before packing */
int nData, /* Number of elements in the regData data array */
int nPrefixReg /* No. of reg prior to regData available for use */
){
Vdbe *v = pParse->pVdbe; /* Stmt under construction */
int bSeq = ((pSort->sortFlags & SORTFLAG_UseSorter)==0);
int nExpr = pSort->pOrderBy->nExpr; /* No. of ORDER BY terms */
int nBase = nExpr + bSeq + nData; /* Fields in sorter record */
int regBase; /* Regs for sorter record */
int regRecord = 0; /* Assembled sorter record */
int nOBSat = pSort->nOBSat; /* ORDER BY terms to skip */
int op; /* Opcode to add sorter record to sorter */
int iLimit; /* LIMIT counter */
int iSkip = 0; /* End of the sorter insert loop */
assert( bSeq==0 || bSeq==1 );
/* Three cases:
** (1) The data to be sorted has already been packed into a Record
** by a prior OP_MakeRecord. In this case nData==1 and regData
** will be completely unrelated to regOrigData.
** (2) All output columns are included in the sort record. In that
** case regData==regOrigData.
** (3) Some output columns are omitted from the sort record due to
** the SQLITE_ENABLE_SORTER_REFERENCE optimization, or due to the
** SQLITE_ECEL_OMITREF optimization, or due to the
** SortCtx.pDeferredRowLoad optimiation. In any of these cases
** regOrigData is 0 to prevent this routine from trying to copy
** values that might not yet exist.
*/
assert( nData==1 || regData==regOrigData || regOrigData==0 );
#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
pSort->addrPush = sqlite3VdbeCurrentAddr(v);
#endif
if( nPrefixReg ){
assert( nPrefixReg==nExpr+bSeq );
regBase = regData - nPrefixReg;
}else{
regBase = pParse->nMem + 1;
pParse->nMem += nBase;
}
assert( pSelect->iOffset==0 || pSelect->iLimit!=0 );
iLimit = pSelect->iOffset ? pSelect->iOffset+1 : pSelect->iLimit;
pSort->labelDone = sqlite3VdbeMakeLabel(pParse);
sqlite3ExprCodeExprList(pParse, pSort->pOrderBy, regBase, regOrigData,
SQLITE_ECEL_DUP | (regOrigData? SQLITE_ECEL_REF : 0));
if( bSeq ){
sqlite3VdbeAddOp2(v, OP_Sequence, pSort->iECursor, regBase+nExpr);
}
if( nPrefixReg==0 && nData>0 ){
sqlite3ExprCodeMove(pParse, regData, regBase+nExpr+bSeq, nData);
}
if( nOBSat>0 ){
int regPrevKey; /* The first nOBSat columns of the previous row */
int addrFirst; /* Address of the OP_IfNot opcode */
int addrJmp; /* Address of the OP_Jump opcode */
VdbeOp *pOp; /* Opcode that opens the sorter */
int nKey; /* Number of sorting key columns, including OP_Sequence */
KeyInfo *pKI; /* Original KeyInfo on the sorter table */
regRecord = makeSorterRecord(pParse, pSort, pSelect, regBase, nBase);
regPrevKey = pParse->nMem+1;
pParse->nMem += pSort->nOBSat;
nKey = nExpr - pSort->nOBSat + bSeq;
if( bSeq ){
addrFirst = sqlite3VdbeAddOp1(v, OP_IfNot, regBase+nExpr);
}else{
addrFirst = sqlite3VdbeAddOp1(v, OP_SequenceTest, pSort->iECursor);
}
VdbeCoverage(v);
sqlite3VdbeAddOp3(v, OP_Compare, regPrevKey, regBase, pSort->nOBSat);
pOp = sqlite3VdbeGetOp(v, pSort->addrSortIndex);
if( pParse->db->mallocFailed ) return;
pOp->p2 = nKey + nData;
pKI = pOp->p4.pKeyInfo;
memset(pKI->aSortFlags, 0, pKI->nKeyField); /* Makes OP_Jump testable */
sqlite3VdbeChangeP4(v, -1, (char*)pKI, P4_KEYINFO);
testcase( pKI->nAllField > pKI->nKeyField+2 );
pOp->p4.pKeyInfo = sqlite3KeyInfoFromExprList(pParse,pSort->pOrderBy,nOBSat,
pKI->nAllField-pKI->nKeyField-1);
pOp = 0; /* Ensure pOp not used after sqltie3VdbeAddOp3() */
addrJmp = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp3(v, OP_Jump, addrJmp+1, 0, addrJmp+1); VdbeCoverage(v);
pSort->labelBkOut = sqlite3VdbeMakeLabel(pParse);
pSort->regReturn = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Gosub, pSort->regReturn, pSort->labelBkOut);
sqlite3VdbeAddOp1(v, OP_ResetSorter, pSort->iECursor);
if( iLimit ){
sqlite3VdbeAddOp2(v, OP_IfNot, iLimit, pSort->labelDone);
VdbeCoverage(v);
}
sqlite3VdbeJumpHere(v, addrFirst);
sqlite3ExprCodeMove(pParse, regBase, regPrevKey, pSort->nOBSat);
sqlite3VdbeJumpHere(v, addrJmp);
}
if( iLimit ){
/* At this point the values for the new sorter entry are stored
** in an array of registers. They need to be composed into a record
** and inserted into the sorter if either (a) there are currently
** less than LIMIT+OFFSET items or (b) the new record is smaller than
** the largest record currently in the sorter. If (b) is true and there
** are already LIMIT+OFFSET items in the sorter, delete the largest
** entry before inserting the new one. This way there are never more
** than LIMIT+OFFSET items in the sorter.
**
** If the new record does not need to be inserted into the sorter,
** jump to the next iteration of the loop. If the pSort->labelOBLopt
** value is not zero, then it is a label of where to jump. Otherwise,
** just bypass the row insert logic. See the header comment on the
** sqlite3WhereOrderByLimitOptLabel() function for additional info.
*/
int iCsr = pSort->iECursor;
sqlite3VdbeAddOp2(v, OP_IfNotZero, iLimit, sqlite3VdbeCurrentAddr(v)+4);
VdbeCoverage(v);
sqlite3VdbeAddOp2(v, OP_Last, iCsr, 0);
iSkip = sqlite3VdbeAddOp4Int(v, OP_IdxLE,
iCsr, 0, regBase+nOBSat, nExpr-nOBSat);
VdbeCoverage(v);
sqlite3VdbeAddOp1(v, OP_Delete, iCsr);
}
if( regRecord==0 ){
regRecord = makeSorterRecord(pParse, pSort, pSelect, regBase, nBase);
}
if( pSort->sortFlags & SORTFLAG_UseSorter ){
op = OP_SorterInsert;
}else{
op = OP_IdxInsert;
}
sqlite3VdbeAddOp4Int(v, op, pSort->iECursor, regRecord,
regBase+nOBSat, nBase-nOBSat);
if( iSkip ){
sqlite3VdbeChangeP2(v, iSkip,
pSort->labelOBLopt ? pSort->labelOBLopt : sqlite3VdbeCurrentAddr(v));
}
#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
pSort->addrPushEnd = sqlite3VdbeCurrentAddr(v)-1;
#endif
}
/*
** Add code to implement the OFFSET
*/
static void codeOffset(
Vdbe *v, /* Generate code into this VM */
int iOffset, /* Register holding the offset counter */
int iContinue /* Jump here to skip the current record */
){
if( iOffset>0 ){
sqlite3VdbeAddOp3(v, OP_IfPos, iOffset, iContinue, 1); VdbeCoverage(v);
VdbeComment((v, "OFFSET"));
}
}
/*
** Add code that will check to make sure the array of registers starting at
** iMem form a distinct entry. This is used by both "SELECT DISTINCT ..." and
** distinct aggregates ("SELECT count(DISTINCT <expr>) ..."). Three strategies
** are available. Which is used depends on the value of parameter eTnctType,
** as follows:
**
** WHERE_DISTINCT_UNORDERED/WHERE_DISTINCT_NOOP:
** Build an ephemeral table that contains all entries seen before and
** skip entries which have been seen before.
**
** Parameter iTab is the cursor number of an ephemeral table that must
** be opened before the VM code generated by this routine is executed.
** The ephemeral cursor table is queried for a record identical to the
** record formed by the current array of registers. If one is found,
** jump to VM address addrRepeat. Otherwise, insert a new record into
** the ephemeral cursor and proceed.
**
** The returned value in this case is a copy of parameter iTab.
**
** WHERE_DISTINCT_ORDERED:
** In this case rows are being delivered sorted order. The ephermal
** table is not required. Instead, the current set of values
** is compared against previous row. If they match, the new row
** is not distinct and control jumps to VM address addrRepeat. Otherwise,
** the VM program proceeds with processing the new row.
**
** The returned value in this case is the register number of the first
** in an array of registers used to store the previous result row so that
** it can be compared to the next. The caller must ensure that this
** register is initialized to NULL. (The fixDistinctOpenEph() routine
** will take care of this initialization.)
**
** WHERE_DISTINCT_UNIQUE:
** In this case it has already been determined that the rows are distinct.
** No special action is required. The return value is zero.
**
** Parameter pEList is the list of expressions used to generated the
** contents of each row. It is used by this routine to determine (a)
** how many elements there are in the array of registers and (b) the
** collation sequences that should be used for the comparisons if
** eTnctType is WHERE_DISTINCT_ORDERED.
*/
static int codeDistinct(
Parse *pParse, /* Parsing and code generating context */
int eTnctType, /* WHERE_DISTINCT_* value */
int iTab, /* A sorting index used to test for distinctness */
int addrRepeat, /* Jump to here if not distinct */
ExprList *pEList, /* Expression for each element */
int regElem /* First element */
){
int iRet = 0;
int nResultCol = pEList->nExpr;
Vdbe *v = pParse->pVdbe;
switch( eTnctType ){
case WHERE_DISTINCT_ORDERED: {
int i;
int iJump; /* Jump destination */
int regPrev; /* Previous row content */
/* Allocate space for the previous row */
iRet = regPrev = pParse->nMem+1;
pParse->nMem += nResultCol;
iJump = sqlite3VdbeCurrentAddr(v) + nResultCol;
for(i=0; i<nResultCol; i++){
CollSeq *pColl = sqlite3ExprCollSeq(pParse, pEList->a[i].pExpr);
if( i<nResultCol-1 ){
sqlite3VdbeAddOp3(v, OP_Ne, regElem+i, iJump, regPrev+i);
VdbeCoverage(v);
}else{
sqlite3VdbeAddOp3(v, OP_Eq, regElem+i, addrRepeat, regPrev+i);
VdbeCoverage(v);
}
sqlite3VdbeChangeP4(v, -1, (const char *)pColl, P4_COLLSEQ);
sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
}
assert( sqlite3VdbeCurrentAddr(v)==iJump || pParse->db->mallocFailed );
sqlite3VdbeAddOp3(v, OP_Copy, regElem, regPrev, nResultCol-1);
break;
}
case WHERE_DISTINCT_UNIQUE: {
/* nothing to do */
break;
}
default: {
int r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp4Int(v, OP_Found, iTab, addrRepeat, regElem, nResultCol);
VdbeCoverage(v);
sqlite3VdbeAddOp3(v, OP_MakeRecord, regElem, nResultCol, r1);
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iTab, r1, regElem, nResultCol);
sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
sqlite3ReleaseTempReg(pParse, r1);
iRet = iTab;
break;
}
}
return iRet;
}
/*
** This routine runs after codeDistinct(). It makes necessary
** adjustments to the OP_OpenEphemeral opcode that the codeDistinct()
** routine made use of. This processing must be done separately since
** sometimes codeDistinct is called before the OP_OpenEphemeral is actually
** laid down.
**
** WHERE_DISTINCT_NOOP:
** WHERE_DISTINCT_UNORDERED:
**
** No adjustments necessary. This function is a no-op.
**
** WHERE_DISTINCT_UNIQUE:
**
** The ephemeral table is not needed. So change the
** OP_OpenEphemeral opcode into an OP_Noop.
**
** WHERE_DISTINCT_ORDERED:
**
** The ephemeral table is not needed. But we do need register
** iVal to be initialized to NULL. So change the OP_OpenEphemeral
** into an OP_Null on the iVal register.
*/
static void fixDistinctOpenEph(
Parse *pParse, /* Parsing and code generating context */
int eTnctType, /* WHERE_DISTINCT_* value */
int iVal, /* Value returned by codeDistinct() */
int iOpenEphAddr /* Address of OP_OpenEphemeral instruction for iTab */
){
if( pParse->nErr==0
&& (eTnctType==WHERE_DISTINCT_UNIQUE || eTnctType==WHERE_DISTINCT_ORDERED)
){
Vdbe *v = pParse->pVdbe;
sqlite3VdbeChangeToNoop(v, iOpenEphAddr);
if( sqlite3VdbeGetOp(v, iOpenEphAddr+1)->opcode==OP_Explain ){
sqlite3VdbeChangeToNoop(v, iOpenEphAddr+1);
}
if( eTnctType==WHERE_DISTINCT_ORDERED ){
/* Change the OP_OpenEphemeral to an OP_Null that sets the MEM_Cleared
** bit on the first register of the previous value. This will cause the
** OP_Ne added in codeDistinct() to always fail on the first iteration of
** the loop even if the first row is all NULLs. */
VdbeOp *pOp = sqlite3VdbeGetOp(v, iOpenEphAddr);
pOp->opcode = OP_Null;
pOp->p1 = 1;
pOp->p2 = iVal;
}
}
}
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
/*
** This function is called as part of inner-loop generation for a SELECT
** statement with an ORDER BY that is not optimized by an index. It
** determines the expressions, if any, that the sorter-reference
** optimization should be used for. The sorter-reference optimization
** is used for SELECT queries like:
**
** SELECT a, bigblob FROM t1 ORDER BY a LIMIT 10
**
** If the optimization is used for expression "bigblob", then instead of
** storing values read from that column in the sorter records, the PK of
** the row from table t1 is stored instead. Then, as records are extracted from
** the sorter to return to the user, the required value of bigblob is
** retrieved directly from table t1. If the values are very large, this
** can be more efficient than storing them directly in the sorter records.
**
** The ExprList_item.fg.bSorterRef flag is set for each expression in pEList
** for which the sorter-reference optimization should be enabled.
** Additionally, the pSort->aDefer[] array is populated with entries
** for all cursors required to evaluate all selected expressions. Finally.
** output variable (*ppExtra) is set to an expression list containing
** expressions for all extra PK values that should be stored in the
** sorter records.
*/
static void selectExprDefer(
Parse *pParse, /* Leave any error here */
SortCtx *pSort, /* Sorter context */
ExprList *pEList, /* Expressions destined for sorter */
ExprList **ppExtra /* Expressions to append to sorter record */
){
int i;
int nDefer = 0;
ExprList *pExtra = 0;
for(i=0; i<pEList->nExpr; i++){
struct ExprList_item *pItem = &pEList->a[i];
if( pItem->u.x.iOrderByCol==0 ){
Expr *pExpr = pItem->pExpr;
Table *pTab;
if( pExpr->op==TK_COLUMN
&& pExpr->iColumn>=0
&& ALWAYS( ExprUseYTab(pExpr) )
&& (pTab = pExpr->y.pTab)!=0
&& IsOrdinaryTable(pTab)
&& (pTab->aCol[pExpr->iColumn].colFlags & COLFLAG_SORTERREF)!=0
){
int j;
for(j=0; j<nDefer; j++){
if( pSort->aDefer[j].iCsr==pExpr->iTable ) break;
}
if( j==nDefer ){
if( nDefer==ArraySize(pSort->aDefer) ){
continue;
}else{
int nKey = 1;
int k;
Index *pPk = 0;
if( !HasRowid(pTab) ){
pPk = sqlite3PrimaryKeyIndex(pTab);
nKey = pPk->nKeyCol;
}
for(k=0; k<nKey; k++){
Expr *pNew = sqlite3PExpr(pParse, TK_COLUMN, 0, 0);
if( pNew ){
pNew->iTable = pExpr->iTable;
assert( ExprUseYTab(pNew) );
pNew->y.pTab = pExpr->y.pTab;
pNew->iColumn = pPk ? pPk->aiColumn[k] : -1;
pExtra = sqlite3ExprListAppend(pParse, pExtra, pNew);
}
}
pSort->aDefer[nDefer].pTab = pExpr->y.pTab;
pSort->aDefer[nDefer].iCsr = pExpr->iTable;
pSort->aDefer[nDefer].nKey = nKey;
nDefer++;
}
}
pItem->fg.bSorterRef = 1;
}
}
}
pSort->nDefer = (u8)nDefer;
*ppExtra = pExtra;
}
#endif
/*
** This routine generates the code for the inside of the inner loop
** of a SELECT.
**
** If srcTab is negative, then the p->pEList expressions
** are evaluated in order to get the data for this row. If srcTab is
** zero or more, then data is pulled from srcTab and p->pEList is used only
** to get the number of columns and the collation sequence for each column.
*/
static void selectInnerLoop(
Parse *pParse, /* The parser context */
Select *p, /* The complete select statement being coded */
int srcTab, /* Pull data from this table if non-negative */
SortCtx *pSort, /* If not NULL, info on how to process ORDER BY */
DistinctCtx *pDistinct, /* If not NULL, info on how to process DISTINCT */
SelectDest *pDest, /* How to dispose of the results */
int iContinue, /* Jump here to continue with next row */
int iBreak /* Jump here to break out of the inner loop */
){
Vdbe *v = pParse->pVdbe;
int i;
int hasDistinct; /* True if the DISTINCT keyword is present */
int eDest = pDest->eDest; /* How to dispose of results */
int iParm = pDest->iSDParm; /* First argument to disposal method */
int nResultCol; /* Number of result columns */
int nPrefixReg = 0; /* Number of extra registers before regResult */
RowLoadInfo sRowLoadInfo; /* Info for deferred row loading */
/* Usually, regResult is the first cell in an array of memory cells
** containing the current result row. In this case regOrig is set to the
** same value. However, if the results are being sent to the sorter, the
** values for any expressions that are also part of the sort-key are omitted
** from this array. In this case regOrig is set to zero. */
int regResult; /* Start of memory holding current results */
int regOrig; /* Start of memory holding full result (or 0) */
assert( v );
assert( p->pEList!=0 );
hasDistinct = pDistinct ? pDistinct->eTnctType : WHERE_DISTINCT_NOOP;
if( pSort && pSort->pOrderBy==0 ) pSort = 0;
if( pSort==0 && !hasDistinct ){
assert( iContinue!=0 );
codeOffset(v, p->iOffset, iContinue);
}
/* Pull the requested columns.
*/
nResultCol = p->pEList->nExpr;
if( pDest->iSdst==0 ){
if( pSort ){
nPrefixReg = pSort->pOrderBy->nExpr;
if( !(pSort->sortFlags & SORTFLAG_UseSorter) ) nPrefixReg++;
pParse->nMem += nPrefixReg;
}
pDest->iSdst = pParse->nMem+1;
pParse->nMem += nResultCol;
}else if( pDest->iSdst+nResultCol > pParse->nMem ){
/* This is an error condition that can result, for example, when a SELECT
** on the right-hand side of an INSERT contains more result columns than
** there are columns in the table on the left. The error will be caught
** and reported later. But we need to make sure enough memory is allocated
** to avoid other spurious errors in the meantime. */
pParse->nMem += nResultCol;
}
pDest->nSdst = nResultCol;
regOrig = regResult = pDest->iSdst;
if( srcTab>=0 ){
for(i=0; i<nResultCol; i++){
sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);
VdbeComment((v, "%s", p->pEList->a[i].zEName));
}
}else if( eDest!=SRT_Exists ){
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
ExprList *pExtra = 0;
#endif
/* If the destination is an EXISTS(...) expression, the actual
** values returned by the SELECT are not required.
*/
u8 ecelFlags; /* "ecel" is an abbreviation of "ExprCodeExprList" */
ExprList *pEList;
if( eDest==SRT_Mem || eDest==SRT_Output || eDest==SRT_Coroutine ){
ecelFlags = SQLITE_ECEL_DUP;
}else{
ecelFlags = 0;
}
if( pSort && hasDistinct==0 && eDest!=SRT_EphemTab && eDest!=SRT_Table ){
/* For each expression in p->pEList that is a copy of an expression in
** the ORDER BY clause (pSort->pOrderBy), set the associated
** iOrderByCol value to one more than the index of the ORDER BY
** expression within the sort-key that pushOntoSorter() will generate.
** This allows the p->pEList field to be omitted from the sorted record,
** saving space and CPU cycles. */
ecelFlags |= (SQLITE_ECEL_OMITREF|SQLITE_ECEL_REF);
for(i=pSort->nOBSat; i<pSort->pOrderBy->nExpr; i++){
int j;
if( (j = pSort->pOrderBy->a[i].u.x.iOrderByCol)>0 ){
p->pEList->a[j-1].u.x.iOrderByCol = i+1-pSort->nOBSat;
}
}
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
selectExprDefer(pParse, pSort, p->pEList, &pExtra);
if( pExtra && pParse->db->mallocFailed==0 ){
/* If there are any extra PK columns to add to the sorter records,
** allocate extra memory cells and adjust the OpenEphemeral
** instruction to account for the larger records. This is only
** required if there are one or more WITHOUT ROWID tables with
** composite primary keys in the SortCtx.aDefer[] array. */
VdbeOp *pOp = sqlite3VdbeGetOp(v, pSort->addrSortIndex);
pOp->p2 += (pExtra->nExpr - pSort->nDefer);
pOp->p4.pKeyInfo->nAllField += (pExtra->nExpr - pSort->nDefer);
pParse->nMem += pExtra->nExpr;
}
#endif
/* Adjust nResultCol to account for columns that are omitted
** from the sorter by the optimizations in this branch */
pEList = p->pEList;
for(i=0; i<pEList->nExpr; i++){
if( pEList->a[i].u.x.iOrderByCol>0
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
|| pEList->a[i].fg.bSorterRef
#endif
){
nResultCol--;
regOrig = 0;
}
}
testcase( regOrig );
testcase( eDest==SRT_Set );
testcase( eDest==SRT_Mem );
testcase( eDest==SRT_Coroutine );
testcase( eDest==SRT_Output );
assert( eDest==SRT_Set || eDest==SRT_Mem
|| eDest==SRT_Coroutine || eDest==SRT_Output
|| eDest==SRT_Upfrom );
}
sRowLoadInfo.regResult = regResult;
sRowLoadInfo.ecelFlags = ecelFlags;
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
sRowLoadInfo.pExtra = pExtra;
sRowLoadInfo.regExtraResult = regResult + nResultCol;
if( pExtra ) nResultCol += pExtra->nExpr;
#endif
if( p->iLimit
&& (ecelFlags & SQLITE_ECEL_OMITREF)!=0
&& nPrefixReg>0
){
assert( pSort!=0 );
assert( hasDistinct==0 );
pSort->pDeferredRowLoad = &sRowLoadInfo;
regOrig = 0;
}else{
innerLoopLoadRow(pParse, p, &sRowLoadInfo);
}
}
/* If the DISTINCT keyword was present on the SELECT statement
** and this row has been seen before, then do not make this row
** part of the result.
*/
if( hasDistinct ){
int eType = pDistinct->eTnctType;
int iTab = pDistinct->tabTnct;
assert( nResultCol==p->pEList->nExpr );
iTab = codeDistinct(pParse, eType, iTab, iContinue, p->pEList, regResult);
fixDistinctOpenEph(pParse, eType, iTab, pDistinct->addrTnct);
if( pSort==0 ){
codeOffset(v, p->iOffset, iContinue);
}
}
switch( eDest ){
/* In this mode, write each query result to the key of the temporary
** table iParm.
*/
#ifndef SQLITE_OMIT_COMPOUND_SELECT
case SRT_Union: {
int r1;
r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1);
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iParm, r1, regResult, nResultCol);
sqlite3ReleaseTempReg(pParse, r1);
break;
}
/* Construct a record from the query result, but instead of
** saving that record, use it as a key to delete elements from
** the temporary table iParm.
*/
case SRT_Except: {
sqlite3VdbeAddOp3(v, OP_IdxDelete, iParm, regResult, nResultCol);
break;
}
#endif /* SQLITE_OMIT_COMPOUND_SELECT */
/* Store the result as data using a unique key.
*/
case SRT_Fifo:
case SRT_DistFifo:
case SRT_Table:
case SRT_EphemTab: {
int r1 = sqlite3GetTempRange(pParse, nPrefixReg+1);
testcase( eDest==SRT_Table );
testcase( eDest==SRT_EphemTab );
testcase( eDest==SRT_Fifo );
testcase( eDest==SRT_DistFifo );
sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1+nPrefixReg);
#ifndef SQLITE_OMIT_CTE
if( eDest==SRT_DistFifo ){
/* If the destination is DistFifo, then cursor (iParm+1) is open
** on an ephemeral index. If the current row is already present
** in the index, do not write it to the output. If not, add the
** current row to the index and proceed with writing it to the
** output table as well. */
int addr = sqlite3VdbeCurrentAddr(v) + 4;
sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, addr, r1, 0);
VdbeCoverage(v);
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iParm+1, r1,regResult,nResultCol);
assert( pSort==0 );
}
#endif
if( pSort ){
assert( regResult==regOrig );
pushOntoSorter(pParse, pSort, p, r1+nPrefixReg, regOrig, 1, nPrefixReg);
}else{
int r2 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, r2);
sqlite3VdbeAddOp3(v, OP_Insert, iParm, r1, r2);
sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
sqlite3ReleaseTempReg(pParse, r2);
}
sqlite3ReleaseTempRange(pParse, r1, nPrefixReg+1);
break;
}
case SRT_Upfrom: {
if( pSort ){
pushOntoSorter(
pParse, pSort, p, regResult, regOrig, nResultCol, nPrefixReg);
}else{
int i2 = pDest->iSDParm2;
int r1 = sqlite3GetTempReg(pParse);
/* If the UPDATE FROM join is an aggregate that matches no rows, it
** might still be trying to return one row, because that is what
** aggregates do. Don't record that empty row in the output table. */
sqlite3VdbeAddOp2(v, OP_IsNull, regResult, iBreak); VdbeCoverage(v);
sqlite3VdbeAddOp3(v, OP_MakeRecord,
regResult+(i2<0), nResultCol-(i2<0), r1);
if( i2<0 ){
sqlite3VdbeAddOp3(v, OP_Insert, iParm, r1, regResult);
}else{
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iParm, r1, regResult, i2);
}
}
break;
}
#ifndef SQLITE_OMIT_SUBQUERY
/* If we are creating a set for an "expr IN (SELECT ...)" construct,
** then there should be a single item on the stack. Write this
** item into the set table with bogus data.
*/
case SRT_Set: {
if( pSort ){
/* At first glance you would think we could optimize out the
** ORDER BY in this case since the order of entries in the set
** does not matter. But there might be a LIMIT clause, in which
** case the order does matter */
pushOntoSorter(
pParse, pSort, p, regResult, regOrig, nResultCol, nPrefixReg);
}else{
int r1 = sqlite3GetTempReg(pParse);
assert( sqlite3Strlen30(pDest->zAffSdst)==nResultCol );
sqlite3VdbeAddOp4(v, OP_MakeRecord, regResult, nResultCol,
r1, pDest->zAffSdst, nResultCol);
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iParm, r1, regResult, nResultCol);
sqlite3ReleaseTempReg(pParse, r1);
}
break;
}
/* If any row exist in the result set, record that fact and abort.
*/
case SRT_Exists: {
sqlite3VdbeAddOp2(v, OP_Integer, 1, iParm);
/* The LIMIT clause will terminate the loop for us */
break;
}
/* If this is a scalar select that is part of an expression, then
** store the results in the appropriate memory cell or array of
** memory cells and break out of the scan loop.
*/
case SRT_Mem: {
if( pSort ){
assert( nResultCol<=pDest->nSdst );
pushOntoSorter(
pParse, pSort, p, regResult, regOrig, nResultCol, nPrefixReg);
}else{
assert( nResultCol==pDest->nSdst );
assert( regResult==iParm );
/* The LIMIT clause will jump out of the loop for us */
}
break;
}
#endif /* #ifndef SQLITE_OMIT_SUBQUERY */
case SRT_Coroutine: /* Send data to a co-routine */
case SRT_Output: { /* Return the results */
testcase( eDest==SRT_Coroutine );
testcase( eDest==SRT_Output );
if( pSort ){
pushOntoSorter(pParse, pSort, p, regResult, regOrig, nResultCol,
nPrefixReg);
}else if( eDest==SRT_Coroutine ){
sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm);
}else{
sqlite3VdbeAddOp2(v, OP_ResultRow, regResult, nResultCol);
}
break;
}
#ifndef SQLITE_OMIT_CTE
/* Write the results into a priority queue that is order according to
** pDest->pOrderBy (in pSO). pDest->iSDParm (in iParm) is the cursor for an
** index with pSO->nExpr+2 columns. Build a key using pSO for the first
** pSO->nExpr columns, then make sure all keys are unique by adding a
** final OP_Sequence column. The last column is the record as a blob.
*/
case SRT_DistQueue:
case SRT_Queue: {
int nKey;
int r1, r2, r3;
int addrTest = 0;
ExprList *pSO;
pSO = pDest->pOrderBy;
assert( pSO );
nKey = pSO->nExpr;
r1 = sqlite3GetTempReg(pParse);
r2 = sqlite3GetTempRange(pParse, nKey+2);
r3 = r2+nKey+1;
if( eDest==SRT_DistQueue ){
/* If the destination is DistQueue, then cursor (iParm+1) is open
** on a second ephemeral index that holds all values every previously
** added to the queue. */
addrTest = sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, 0,
regResult, nResultCol);
VdbeCoverage(v);
}
sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r3);
if( eDest==SRT_DistQueue ){
sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm+1, r3);
sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
}
for(i=0; i<nKey; i++){
sqlite3VdbeAddOp2(v, OP_SCopy,
regResult + pSO->a[i].u.x.iOrderByCol - 1,
r2+i);
}
sqlite3VdbeAddOp2(v, OP_Sequence, iParm, r2+nKey);
sqlite3VdbeAddOp3(v, OP_MakeRecord, r2, nKey+2, r1);
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iParm, r1, r2, nKey+2);
if( addrTest ) sqlite3VdbeJumpHere(v, addrTest);
sqlite3ReleaseTempReg(pParse, r1);
sqlite3ReleaseTempRange(pParse, r2, nKey+2);
break;
}
#endif /* SQLITE_OMIT_CTE */
#if !defined(SQLITE_OMIT_TRIGGER)
/* Discard the results. This is used for SELECT statements inside
** the body of a TRIGGER. The purpose of such selects is to call
** user-defined functions that have side effects. We do not care
** about the actual results of the select.
*/
default: {
assert( eDest==SRT_Discard );
break;
}
#endif
}
/* Jump to the end of the loop if the LIMIT is reached. Except, if
** there is a sorter, in which case the sorter has already limited
** the output for us.
*/
if( pSort==0 && p->iLimit ){
sqlite3VdbeAddOp2(v, OP_DecrJumpZero, p->iLimit, iBreak); VdbeCoverage(v);
}
}
/*
** Allocate a KeyInfo object sufficient for an index of N key columns and
** X extra columns.
*/
KeyInfo *sqlite3KeyInfoAlloc(sqlite3 *db, int N, int X){
int nExtra = (N+X)*(sizeof(CollSeq*)+1) - sizeof(CollSeq*);
KeyInfo *p = sqlite3DbMallocRawNN(db, sizeof(KeyInfo) + nExtra);
if( p ){
p->aSortFlags = (u8*)&p->aColl[N+X];
p->nKeyField = (u16)N;
p->nAllField = (u16)(N+X);
p->enc = ENC(db);
p->db = db;
p->nRef = 1;
memset(&p[1], 0, nExtra);
}else{
return (KeyInfo*)sqlite3OomFault(db);
}
return p;
}
/*
** Deallocate a KeyInfo object
*/
void sqlite3KeyInfoUnref(KeyInfo *p){
if( p ){
assert( p->db!=0 );
assert( p->nRef>0 );
p->nRef--;
if( p->nRef==0 ) sqlite3DbNNFreeNN(p->db, p);
}
}
/*
** Make a new pointer to a KeyInfo object
*/
KeyInfo *sqlite3KeyInfoRef(KeyInfo *p){
if( p ){
assert( p->nRef>0 );
p->nRef++;
}
return p;
}
#ifdef SQLITE_DEBUG
/*
** Return TRUE if a KeyInfo object can be change. The KeyInfo object
** can only be changed if this is just a single reference to the object.
**
** This routine is used only inside of assert() statements.
*/
int sqlite3KeyInfoIsWriteable(KeyInfo *p){ return p->nRef==1; }
#endif /* SQLITE_DEBUG */
/*
** Given an expression list, generate a KeyInfo structure that records
** the collating sequence for each expression in that expression list.
**
** If the ExprList is an ORDER BY or GROUP BY clause then the resulting
** KeyInfo structure is appropriate for initializing a virtual index to
** implement that clause. If the ExprList is the result set of a SELECT
** then the KeyInfo structure is appropriate for initializing a virtual
** index to implement a DISTINCT test.
**
** Space to hold the KeyInfo structure is obtained from malloc. The calling
** function is responsible for seeing that this structure is eventually
** freed.
*/
KeyInfo *sqlite3KeyInfoFromExprList(
Parse *pParse, /* Parsing context */
ExprList *pList, /* Form the KeyInfo object from this ExprList */
int iStart, /* Begin with this column of pList */
int nExtra /* Add this many extra columns to the end */
){
int nExpr;
KeyInfo *pInfo;
struct ExprList_item *pItem;
sqlite3 *db = pParse->db;
int i;
nExpr = pList->nExpr;
pInfo = sqlite3KeyInfoAlloc(db, nExpr-iStart, nExtra+1);
if( pInfo ){
assert( sqlite3KeyInfoIsWriteable(pInfo) );
for(i=iStart, pItem=pList->a+iStart; i<nExpr; i++, pItem++){
pInfo->aColl[i-iStart] = sqlite3ExprNNCollSeq(pParse, pItem->pExpr);
pInfo->aSortFlags[i-iStart] = pItem->fg.sortFlags;
}
}
return pInfo;
}
/*
** Name of the connection operator, used for error messages.
*/
const char *sqlite3SelectOpName(int id){
char *z;
switch( id ){
case TK_ALL: z = "UNION ALL"; break;
case TK_INTERSECT: z = "INTERSECT"; break;
case TK_EXCEPT: z = "EXCEPT"; break;
default: z = "UNION"; break;
}
return z;
}
#ifndef SQLITE_OMIT_EXPLAIN
/*
** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function
** is a no-op. Otherwise, it adds a single row of output to the EQP result,
** where the caption is of the form:
**
** "USE TEMP B-TREE FOR xxx"
**
** where xxx is one of "DISTINCT", "ORDER BY" or "GROUP BY". Exactly which
** is determined by the zUsage argument.
*/
static void explainTempTable(Parse *pParse, const char *zUsage){
ExplainQueryPlan((pParse, 0, "USE TEMP B-TREE FOR %s", zUsage));
}
/*
** Assign expression b to lvalue a. A second, no-op, version of this macro
** is provided when SQLITE_OMIT_EXPLAIN is defined. This allows the code
** in sqlite3Select() to assign values to structure member variables that
** only exist if SQLITE_OMIT_EXPLAIN is not defined without polluting the
** code with #ifndef directives.
*/
# define explainSetInteger(a, b) a = b
#else
/* No-op versions of the explainXXX() functions and macros. */
# define explainTempTable(y,z)
# define explainSetInteger(y,z)
#endif
/*
** If the inner loop was generated using a non-null pOrderBy argument,
** then the results were placed in a sorter. After the loop is terminated
** we need to run the sorter and output the results. The following
** routine generates the code needed to do that.
*/
static void generateSortTail(
Parse *pParse, /* Parsing context */
Select *p, /* The SELECT statement */
SortCtx *pSort, /* Information on the ORDER BY clause */
int nColumn, /* Number of columns of data */
SelectDest *pDest /* Write the sorted results here */
){
Vdbe *v = pParse->pVdbe; /* The prepared statement */
int addrBreak = pSort->labelDone; /* Jump here to exit loop */
int addrContinue = sqlite3VdbeMakeLabel(pParse);/* Jump here for next cycle */
int addr; /* Top of output loop. Jump for Next. */
int addrOnce = 0;
int iTab;
ExprList *pOrderBy = pSort->pOrderBy;
int eDest = pDest->eDest;
int iParm = pDest->iSDParm;
int regRow;
int regRowid;
int iCol;
int nKey; /* Number of key columns in sorter record */
int iSortTab; /* Sorter cursor to read from */
int i;
int bSeq; /* True if sorter record includes seq. no. */
int nRefKey = 0;
struct ExprList_item *aOutEx = p->pEList->a;
#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
int addrExplain; /* Address of OP_Explain instruction */
#endif
ExplainQueryPlan2(addrExplain, (pParse, 0,
"USE TEMP B-TREE FOR %sORDER BY", pSort->nOBSat>0?"RIGHT PART OF ":"")
);
sqlite3VdbeScanStatusRange(v, addrExplain,pSort->addrPush,pSort->addrPushEnd);
sqlite3VdbeScanStatusCounters(v, addrExplain, addrExplain, pSort->addrPush);
assert( addrBreak<0 );
if( pSort->labelBkOut ){
sqlite3VdbeAddOp2(v, OP_Gosub, pSort->regReturn, pSort->labelBkOut);
sqlite3VdbeGoto(v, addrBreak);
sqlite3VdbeResolveLabel(v, pSort->labelBkOut);
}
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
/* Open any cursors needed for sorter-reference expressions */
for(i=0; i<pSort->nDefer; i++){
Table *pTab = pSort->aDefer[i].pTab;
int iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
sqlite3OpenTable(pParse, pSort->aDefer[i].iCsr, iDb, pTab, OP_OpenRead);
nRefKey = MAX(nRefKey, pSort->aDefer[i].nKey);
}
#endif
iTab = pSort->iECursor;
if( eDest==SRT_Output || eDest==SRT_Coroutine || eDest==SRT_Mem ){
if( eDest==SRT_Mem && p->iOffset ){
sqlite3VdbeAddOp2(v, OP_Null, 0, pDest->iSdst);
}
regRowid = 0;
regRow = pDest->iSdst;
}else{
regRowid = sqlite3GetTempReg(pParse);
if( eDest==SRT_EphemTab || eDest==SRT_Table ){
regRow = sqlite3GetTempReg(pParse);
nColumn = 0;
}else{
regRow = sqlite3GetTempRange(pParse, nColumn);
}
}
nKey = pOrderBy->nExpr - pSort->nOBSat;
if( pSort->sortFlags & SORTFLAG_UseSorter ){
int regSortOut = ++pParse->nMem;
iSortTab = pParse->nTab++;
if( pSort->labelBkOut ){
addrOnce = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v);
}
sqlite3VdbeAddOp3(v, OP_OpenPseudo, iSortTab, regSortOut,
nKey+1+nColumn+nRefKey);
if( addrOnce ) sqlite3VdbeJumpHere(v, addrOnce);
addr = 1 + sqlite3VdbeAddOp2(v, OP_SorterSort, iTab, addrBreak);
VdbeCoverage(v);
assert( p->iLimit==0 && p->iOffset==0 );
sqlite3VdbeAddOp3(v, OP_SorterData, iTab, regSortOut, iSortTab);
bSeq = 0;
}else{
addr = 1 + sqlite3VdbeAddOp2(v, OP_Sort, iTab, addrBreak); VdbeCoverage(v);
codeOffset(v, p->iOffset, addrContinue);
iSortTab = iTab;
bSeq = 1;
if( p->iOffset>0 ){
sqlite3VdbeAddOp2(v, OP_AddImm, p->iLimit, -1);
}
}
for(i=0, iCol=nKey+bSeq-1; i<nColumn; i++){
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
if( aOutEx[i].fg.bSorterRef ) continue;
#endif
if( aOutEx[i].u.x.iOrderByCol==0 ) iCol++;
}
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
if( pSort->nDefer ){
int iKey = iCol+1;
int regKey = sqlite3GetTempRange(pParse, nRefKey);
for(i=0; i<pSort->nDefer; i++){
int iCsr = pSort->aDefer[i].iCsr;
Table *pTab = pSort->aDefer[i].pTab;
int nKey = pSort->aDefer[i].nKey;
sqlite3VdbeAddOp1(v, OP_NullRow, iCsr);
if( HasRowid(pTab) ){
sqlite3VdbeAddOp3(v, OP_Column, iSortTab, iKey++, regKey);
sqlite3VdbeAddOp3(v, OP_SeekRowid, iCsr,
sqlite3VdbeCurrentAddr(v)+1, regKey);
}else{
int k;
int iJmp;
assert( sqlite3PrimaryKeyIndex(pTab)->nKeyCol==nKey );
for(k=0; k<nKey; k++){
sqlite3VdbeAddOp3(v, OP_Column, iSortTab, iKey++, regKey+k);
}
iJmp = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp4Int(v, OP_SeekGE, iCsr, iJmp+2, regKey, nKey);
sqlite3VdbeAddOp4Int(v, OP_IdxLE, iCsr, iJmp+3, regKey, nKey);
sqlite3VdbeAddOp1(v, OP_NullRow, iCsr);
}
}
sqlite3ReleaseTempRange(pParse, regKey, nRefKey);
}
#endif
for(i=nColumn-1; i>=0; i--){
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
if( aOutEx[i].fg.bSorterRef ){
sqlite3ExprCode(pParse, aOutEx[i].pExpr, regRow+i);
}else
#endif
{
int iRead;
if( aOutEx[i].u.x.iOrderByCol ){
iRead = aOutEx[i].u.x.iOrderByCol-1;
}else{
iRead = iCol--;
}
sqlite3VdbeAddOp3(v, OP_Column, iSortTab, iRead, regRow+i);
VdbeComment((v, "%s", aOutEx[i].zEName));
}
}
sqlite3VdbeScanStatusRange(v, addrExplain, addrExplain, -1);
switch( eDest ){
case SRT_Table:
case SRT_EphemTab: {
sqlite3VdbeAddOp3(v, OP_Column, iSortTab, nKey+bSeq, regRow);
sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, regRowid);
sqlite3VdbeAddOp3(v, OP_Insert, iParm, regRow, regRowid);
sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
break;
}
#ifndef SQLITE_OMIT_SUBQUERY
case SRT_Set: {
assert( nColumn==sqlite3Strlen30(pDest->zAffSdst) );
sqlite3VdbeAddOp4(v, OP_MakeRecord, regRow, nColumn, regRowid,
pDest->zAffSdst, nColumn);
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iParm, regRowid, regRow, nColumn);
break;
}
case SRT_Mem: {
/* The LIMIT clause will terminate the loop for us */
break;
}
#endif
case SRT_Upfrom: {
int i2 = pDest->iSDParm2;
int r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_MakeRecord,regRow+(i2<0),nColumn-(i2<0),r1);
if( i2<0 ){
sqlite3VdbeAddOp3(v, OP_Insert, iParm, r1, regRow);
}else{
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iParm, r1, regRow, i2);
}
break;
}
default: {
assert( eDest==SRT_Output || eDest==SRT_Coroutine );
testcase( eDest==SRT_Output );
testcase( eDest==SRT_Coroutine );
if( eDest==SRT_Output ){
sqlite3VdbeAddOp2(v, OP_ResultRow, pDest->iSdst, nColumn);
}else{
sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm);
}
break;
}
}
if( regRowid ){
if( eDest==SRT_Set ){
sqlite3ReleaseTempRange(pParse, regRow, nColumn);
}else{
sqlite3ReleaseTempReg(pParse, regRow);
}
sqlite3ReleaseTempReg(pParse, regRowid);
}
/* The bottom of the loop
*/
sqlite3VdbeResolveLabel(v, addrContinue);
if( pSort->sortFlags & SORTFLAG_UseSorter ){
sqlite3VdbeAddOp2(v, OP_SorterNext, iTab, addr); VdbeCoverage(v);
}else{
sqlite3VdbeAddOp2(v, OP_Next, iTab, addr); VdbeCoverage(v);
}
sqlite3VdbeScanStatusRange(v, addrExplain, sqlite3VdbeCurrentAddr(v)-1, -1);
if( pSort->regReturn ) sqlite3VdbeAddOp1(v, OP_Return, pSort->regReturn);
sqlite3VdbeResolveLabel(v, addrBreak);
}
/*
** Return a pointer to a string containing the 'declaration type' of the
** expression pExpr. The string may be treated as static by the caller.
**
** The declaration type is the exact datatype definition extracted from the
** original CREATE TABLE statement if the expression is a column. The
** declaration type for a ROWID field is INTEGER. Exactly when an expression
** is considered a column can be complex in the presence of subqueries. The
** result-set expression in all of the following SELECT statements is
** considered a column by this function.
**
** SELECT col FROM tbl;
** SELECT (SELECT col FROM tbl;
** SELECT (SELECT col FROM tbl);
** SELECT abc FROM (SELECT col AS abc FROM tbl);
**
** The declaration type for any expression other than a column is NULL.
**
** This routine has either 3 or 6 parameters depending on whether or not
** the SQLITE_ENABLE_COLUMN_METADATA compile-time option is used.
*/
#ifdef SQLITE_ENABLE_COLUMN_METADATA
# define columnType(A,B,C,D,E) columnTypeImpl(A,B,C,D,E)
#else /* if !defined(SQLITE_ENABLE_COLUMN_METADATA) */
# define columnType(A,B,C,D,E) columnTypeImpl(A,B)
#endif
static const char *columnTypeImpl(
NameContext *pNC,
#ifndef SQLITE_ENABLE_COLUMN_METADATA
Expr *pExpr
#else
Expr *pExpr,
const char **pzOrigDb,
const char **pzOrigTab,
const char **pzOrigCol
#endif
){
char const *zType = 0;
int j;
#ifdef SQLITE_ENABLE_COLUMN_METADATA
char const *zOrigDb = 0;
char const *zOrigTab = 0;
char const *zOrigCol = 0;
#endif
assert( pExpr!=0 );
assert( pNC->pSrcList!=0 );
switch( pExpr->op ){
case TK_COLUMN: {
/* The expression is a column. Locate the table the column is being
** extracted from in NameContext.pSrcList. This table may be real
** database table or a subquery.
*/
Table *pTab = 0; /* Table structure column is extracted from */
Select *pS = 0; /* Select the column is extracted from */
int iCol = pExpr->iColumn; /* Index of column in pTab */
while( pNC && !pTab ){
SrcList *pTabList = pNC->pSrcList;
for(j=0;j<pTabList->nSrc && pTabList->a[j].iCursor!=pExpr->iTable;j++);
if( j<pTabList->nSrc ){
pTab = pTabList->a[j].pTab;
pS = pTabList->a[j].pSelect;
}else{
pNC = pNC->pNext;
}
}
if( pTab==0 ){
/* At one time, code such as "SELECT new.x" within a trigger would
** cause this condition to run. Since then, we have restructured how
** trigger code is generated and so this condition is no longer
** possible. However, it can still be true for statements like
** the following:
**
** CREATE TABLE t1(col INTEGER);
** SELECT (SELECT t1.col) FROM FROM t1;
**
** when columnType() is called on the expression "t1.col" in the
** sub-select. In this case, set the column type to NULL, even
** though it should really be "INTEGER".
**
** This is not a problem, as the column type of "t1.col" is never
** used. When columnType() is called on the expression
** "(SELECT t1.col)", the correct type is returned (see the TK_SELECT
** branch below. */
break;
}
assert( pTab && ExprUseYTab(pExpr) && pExpr->y.pTab==pTab );
if( pS ){
/* The "table" is actually a sub-select or a view in the FROM clause
** of the SELECT statement. Return the declaration type and origin
** data for the result-set column of the sub-select.
*/
if( iCol<pS->pEList->nExpr
#ifdef SQLITE_ALLOW_ROWID_IN_VIEW
&& iCol>=0
#else
&& ALWAYS(iCol>=0)
#endif
){
/* If iCol is less than zero, then the expression requests the
** rowid of the sub-select or view. This expression is legal (see
** test case misc2.2.2) - it always evaluates to NULL.
*/
NameContext sNC;
Expr *p = pS->pEList->a[iCol].pExpr;
sNC.pSrcList = pS->pSrc;
sNC.pNext = pNC;
sNC.pParse = pNC->pParse;
zType = columnType(&sNC, p,&zOrigDb,&zOrigTab,&zOrigCol);
}
}else{
/* A real table or a CTE table */
assert( !pS );
#ifdef SQLITE_ENABLE_COLUMN_METADATA
if( iCol<0 ) iCol = pTab->iPKey;
assert( iCol==XN_ROWID || (iCol>=0 && iCol<pTab->nCol) );
if( iCol<0 ){
zType = "INTEGER";
zOrigCol = "rowid";
}else{
zOrigCol = pTab->aCol[iCol].zCnName;
zType = sqlite3ColumnType(&pTab->aCol[iCol],0);
}
zOrigTab = pTab->zName;
if( pNC->pParse && pTab->pSchema ){
int iDb = sqlite3SchemaToIndex(pNC->pParse->db, pTab->pSchema);
zOrigDb = pNC->pParse->db->aDb[iDb].zDbSName;
}
#else
assert( iCol==XN_ROWID || (iCol>=0 && iCol<pTab->nCol) );
if( iCol<0 ){
zType = "INTEGER";
}else{
zType = sqlite3ColumnType(&pTab->aCol[iCol],0);
}
#endif
}
break;
}
#ifndef SQLITE_OMIT_SUBQUERY
case TK_SELECT: {
/* The expression is a sub-select. Return the declaration type and
** origin info for the single column in the result set of the SELECT
** statement.
*/
NameContext sNC;
Select *pS;
Expr *p;
assert( ExprUseXSelect(pExpr) );
pS = pExpr->x.pSelect;
p = pS->pEList->a[0].pExpr;
sNC.pSrcList = pS->pSrc;
sNC.pNext = pNC;
sNC.pParse = pNC->pParse;
zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol);
break;
}
#endif
}
#ifdef SQLITE_ENABLE_COLUMN_METADATA
if( pzOrigDb ){
assert( pzOrigTab && pzOrigCol );
*pzOrigDb = zOrigDb;
*pzOrigTab = zOrigTab;
*pzOrigCol = zOrigCol;
}
#endif
return zType;
}
/*
** Generate code that will tell the VDBE the declaration types of columns
** in the result set.
*/
static void generateColumnTypes(
Parse *pParse, /* Parser context */
SrcList *pTabList, /* List of tables */
ExprList *pEList /* Expressions defining the result set */
){
#ifndef SQLITE_OMIT_DECLTYPE
Vdbe *v = pParse->pVdbe;
int i;
NameContext sNC;
sNC.pSrcList = pTabList;
sNC.pParse = pParse;
sNC.pNext = 0;
for(i=0; i<pEList->nExpr; i++){
Expr *p = pEList->a[i].pExpr;
const char *zType;
#ifdef SQLITE_ENABLE_COLUMN_METADATA
const char *zOrigDb = 0;
const char *zOrigTab = 0;
const char *zOrigCol = 0;
zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol);
/* The vdbe must make its own copy of the column-type and other
** column specific strings, in case the schema is reset before this
** virtual machine is deleted.
*/
sqlite3VdbeSetColName(v, i, COLNAME_DATABASE, zOrigDb, SQLITE_TRANSIENT);
sqlite3VdbeSetColName(v, i, COLNAME_TABLE, zOrigTab, SQLITE_TRANSIENT);
sqlite3VdbeSetColName(v, i, COLNAME_COLUMN, zOrigCol, SQLITE_TRANSIENT);
#else
zType = columnType(&sNC, p, 0, 0, 0);
#endif
sqlite3VdbeSetColName(v, i, COLNAME_DECLTYPE, zType, SQLITE_TRANSIENT);
}
#endif /* !defined(SQLITE_OMIT_DECLTYPE) */
}
/*
** Compute the column names for a SELECT statement.
**
** The only guarantee that SQLite makes about column names is that if the
** column has an AS clause assigning it a name, that will be the name used.
** That is the only documented guarantee. However, countless applications
** developed over the years have made baseless assumptions about column names
** and will break if those assumptions changes. Hence, use extreme caution
** when modifying this routine to avoid breaking legacy.
**
** See Also: sqlite3ColumnsFromExprList()
**
** The PRAGMA short_column_names and PRAGMA full_column_names settings are
** deprecated. The default setting is short=ON, full=OFF. 99.9% of all
** applications should operate this way. Nevertheless, we need to support the
** other modes for legacy:
**
** short=OFF, full=OFF: Column name is the text of the expression has it
** originally appears in the SELECT statement. In
** other words, the zSpan of the result expression.
**
** short=ON, full=OFF: (This is the default setting). If the result
** refers directly to a table column, then the
** result column name is just the table column
** name: COLUMN. Otherwise use zSpan.
**
** full=ON, short=ANY: If the result refers directly to a table column,
** then the result column name with the table name
** prefix, ex: TABLE.COLUMN. Otherwise use zSpan.
*/
void sqlite3GenerateColumnNames(
Parse *pParse, /* Parser context */
Select *pSelect /* Generate column names for this SELECT statement */
){
Vdbe *v = pParse->pVdbe;
int i;
Table *pTab;
SrcList *pTabList;
ExprList *pEList;
sqlite3 *db = pParse->db;
int fullName; /* TABLE.COLUMN if no AS clause and is a direct table ref */
int srcName; /* COLUMN or TABLE.COLUMN if no AS clause and is direct */
#ifndef SQLITE_OMIT_EXPLAIN
/* If this is an EXPLAIN, skip this step */
if( pParse->explain ){
return;
}
#endif
if( pParse->colNamesSet ) return;
/* Column names are determined by the left-most term of a compound select */
while( pSelect->pPrior ) pSelect = pSelect->pPrior;
TREETRACE(0x80,pParse,pSelect,("generating column names\n"));
pTabList = pSelect->pSrc;
pEList = pSelect->pEList;
assert( v!=0 );
assert( pTabList!=0 );
pParse->colNamesSet = 1;
fullName = (db->flags & SQLITE_FullColNames)!=0;
srcName = (db->flags & SQLITE_ShortColNames)!=0 || fullName;
sqlite3VdbeSetNumCols(v, pEList->nExpr);
for(i=0; i<pEList->nExpr; i++){
Expr *p = pEList->a[i].pExpr;
assert( p!=0 );
assert( p->op!=TK_AGG_COLUMN ); /* Agg processing has not run yet */
assert( p->op!=TK_COLUMN
|| (ExprUseYTab(p) && p->y.pTab!=0) ); /* Covering idx not yet coded */
if( pEList->a[i].zEName && pEList->a[i].fg.eEName==ENAME_NAME ){
/* An AS clause always takes first priority */
char *zName = pEList->a[i].zEName;
sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, SQLITE_TRANSIENT);
}else if( srcName && p->op==TK_COLUMN ){
char *zCol;
int iCol = p->iColumn;
pTab = p->y.pTab;
assert( pTab!=0 );
if( iCol<0 ) iCol = pTab->iPKey;
assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) );
if( iCol<0 ){
zCol = "rowid";
}else{
zCol = pTab->aCol[iCol].zCnName;
}
if( fullName ){
char *zName = 0;
zName = sqlite3MPrintf(db, "%s.%s", pTab->zName, zCol);
sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, SQLITE_DYNAMIC);
}else{
sqlite3VdbeSetColName(v, i, COLNAME_NAME, zCol, SQLITE_TRANSIENT);
}
}else{
const char *z = pEList->a[i].zEName;
z = z==0 ? sqlite3MPrintf(db, "column%d", i+1) : sqlite3DbStrDup(db, z);
sqlite3VdbeSetColName(v, i, COLNAME_NAME, z, SQLITE_DYNAMIC);
}
}
generateColumnTypes(pParse, pTabList, pEList);
}
/*
** Given an expression list (which is really the list of expressions
** that form the result set of a SELECT statement) compute appropriate
** column names for a table that would hold the expression list.
**
** All column names will be unique.
**
** Only the column names are computed. Column.zType, Column.zColl,
** and other fields of Column are zeroed.
**
** Return SQLITE_OK on success. If a memory allocation error occurs,
** store NULL in *paCol and 0 in *pnCol and return SQLITE_NOMEM.
**
** The only guarantee that SQLite makes about column names is that if the
** column has an AS clause assigning it a name, that will be the name used.
** That is the only documented guarantee. However, countless applications
** developed over the years have made baseless assumptions about column names
** and will break if those assumptions changes. Hence, use extreme caution
** when modifying this routine to avoid breaking legacy.
**
** See Also: sqlite3GenerateColumnNames()
*/
int sqlite3ColumnsFromExprList(
Parse *pParse, /* Parsing context */
ExprList *pEList, /* Expr list from which to derive column names */
i16 *pnCol, /* Write the number of columns here */
Column **paCol /* Write the new column list here */
){
sqlite3 *db = pParse->db; /* Database connection */
int i, j; /* Loop counters */
u32 cnt; /* Index added to make the name unique */
Column *aCol, *pCol; /* For looping over result columns */
int nCol; /* Number of columns in the result set */
char *zName; /* Column name */
int nName; /* Size of name in zName[] */
Hash ht; /* Hash table of column names */
Table *pTab;
sqlite3HashInit(&ht);
if( pEList ){
nCol = pEList->nExpr;
aCol = sqlite3DbMallocZero(db, sizeof(aCol[0])*nCol);
testcase( aCol==0 );
if( NEVER(nCol>32767) ) nCol = 32767;
}else{
nCol = 0;
aCol = 0;
}
assert( nCol==(i16)nCol );
*pnCol = nCol;
*paCol = aCol;
for(i=0, pCol=aCol; i<nCol && !pParse->nErr; i++, pCol++){
struct ExprList_item *pX = &pEList->a[i];
struct ExprList_item *pCollide;
/* Get an appropriate name for the column
*/
if( (zName = pX->zEName)!=0 && pX->fg.eEName==ENAME_NAME ){
/* If the column contains an "AS <name>" phrase, use <name> as the name */
}else{
Expr *pColExpr = sqlite3ExprSkipCollateAndLikely(pX->pExpr);
while( ALWAYS(pColExpr!=0) && pColExpr->op==TK_DOT ){
pColExpr = pColExpr->pRight;
assert( pColExpr!=0 );
}
if( pColExpr->op==TK_COLUMN
&& ALWAYS( ExprUseYTab(pColExpr) )
&& ALWAYS( pColExpr->y.pTab!=0 )
){
/* For columns use the column name name */
int iCol = pColExpr->iColumn;
pTab = pColExpr->y.pTab;
if( iCol<0 ) iCol = pTab->iPKey;
zName = iCol>=0 ? pTab->aCol[iCol].zCnName : "rowid";
}else if( pColExpr->op==TK_ID ){
assert( !ExprHasProperty(pColExpr, EP_IntValue) );
zName = pColExpr->u.zToken;
}else{
/* Use the original text of the column expression as its name */
assert( zName==pX->zEName ); /* pointer comparison intended */
}
}
if( zName && !sqlite3IsTrueOrFalse(zName) ){
zName = sqlite3DbStrDup(db, zName);
}else{
zName = sqlite3MPrintf(db,"column%d",i+1);
}
/* Make sure the column name is unique. If the name is not unique,
** append an integer to the name so that it becomes unique.
*/
cnt = 0;
while( zName && (pCollide = sqlite3HashFind(&ht, zName))!=0 ){
if( pCollide->fg.bUsingTerm ){
pCol->colFlags |= COLFLAG_NOEXPAND;
}
nName = sqlite3Strlen30(zName);
if( nName>0 ){
for(j=nName-1; j>0 && sqlite3Isdigit(zName[j]); j--){}
if( zName[j]==':' ) nName = j;
}
zName = sqlite3MPrintf(db, "%.*z:%u", nName, zName, ++cnt);
sqlite3ProgressCheck(pParse);
if( cnt>3 ){
sqlite3_randomness(sizeof(cnt), &cnt);
}
}
pCol->zCnName = zName;
pCol->hName = sqlite3StrIHash(zName);
if( pX->fg.bNoExpand ){
pCol->colFlags |= COLFLAG_NOEXPAND;
}
sqlite3ColumnPropertiesFromName(0, pCol);
if( zName && sqlite3HashInsert(&ht, zName, pX)==pX ){
sqlite3OomFault(db);
}
}
sqlite3HashClear(&ht);
if( pParse->nErr ){
for(j=0; j<i; j++){
sqlite3DbFree(db, aCol[j].zCnName);
}
sqlite3DbFree(db, aCol);
*paCol = 0;
*pnCol = 0;
return pParse->rc;
}
return SQLITE_OK;
}
/*
** pTab is a transient Table object that represents a subquery of some
** kind (maybe a parenthesized subquery in the FROM clause of a larger
** query, or a VIEW, or a CTE). This routine computes type information
** for that Table object based on the Select object that implements the
** subquery. For the purposes of this routine, "type infomation" means:
**
** * The datatype name, as it might appear in a CREATE TABLE statement
** * Which collating sequence to use for the column
** * The affinity of the column
*/
void sqlite3SubqueryColumnTypes(
Parse *pParse, /* Parsing contexts */
Table *pTab, /* Add column type information to this table */
Select *pSelect, /* SELECT used to determine types and collations */
char aff /* Default affinity. */
){
sqlite3 *db = pParse->db;
Column *pCol;
CollSeq *pColl;
int i,j;
Expr *p;
struct ExprList_item *a;
NameContext sNC;
assert( pSelect!=0 );
assert( (pSelect->selFlags & SF_Resolved)!=0 );
assert( pTab->nCol==pSelect->pEList->nExpr || pParse->nErr>0 );
assert( aff==SQLITE_AFF_NONE || aff==SQLITE_AFF_BLOB );
if( db->mallocFailed ) return;
while( pSelect->pPrior ) pSelect = pSelect->pPrior;
a = pSelect->pEList->a;
memset(&sNC, 0, sizeof(sNC));
sNC.pSrcList = pSelect->pSrc;
for(i=0, pCol=pTab->aCol; i<pTab->nCol; i++, pCol++){
const char *zType;
i64 n;
pTab->tabFlags |= (pCol->colFlags & COLFLAG_NOINSERT);
p = a[i].pExpr;
/* pCol->szEst = ... // Column size est for SELECT tables never used */
pCol->affinity = sqlite3ExprAffinity(p);
if( pCol->affinity<=SQLITE_AFF_NONE ){
pCol->affinity = aff;
}else if( pCol->affinity>=SQLITE_AFF_NUMERIC && p->op==TK_CAST ){
pCol->affinity = SQLITE_AFF_FLEXNUM;
}
if( pCol->affinity>=SQLITE_AFF_TEXT && pSelect->pNext ){
int m = 0;
Select *pS2;
for(m=0, pS2=pSelect->pNext; pS2; pS2=pS2->pNext){
m |= sqlite3ExprDataType(pS2->pEList->a[i].pExpr);
}
if( pCol->affinity==SQLITE_AFF_TEXT && (m&0x01)!=0 ){
pCol->affinity = SQLITE_AFF_BLOB;
}else
if( pCol->affinity>=SQLITE_AFF_NUMERIC && (m&0x02)!=0 ){
pCol->affinity = SQLITE_AFF_BLOB;
}
}
zType = columnType(&sNC, p, 0, 0, 0);
if( zType==0 || pCol->affinity!=sqlite3AffinityType(zType, 0) ){
if( pCol->affinity==SQLITE_AFF_NUMERIC
|| pCol->affinity==SQLITE_AFF_FLEXNUM
){
zType = "NUM";
}else{
zType = 0;
for(j=1; j<SQLITE_N_STDTYPE; j++){
if( sqlite3StdTypeAffinity[j]==pCol->affinity ){
zType = sqlite3StdType[j];
break;
}
}
}
}
if( zType ){
i64 m = sqlite3Strlen30(zType);
n = sqlite3Strlen30(pCol->zCnName);
pCol->zCnName = sqlite3DbReallocOrFree(db, pCol->zCnName, n+m+2);
if( pCol->zCnName ){
memcpy(&pCol->zCnName[n+1], zType, m+1);
pCol->colFlags |= COLFLAG_HASTYPE;
}else{
testcase( pCol->colFlags & COLFLAG_HASTYPE );
pCol->colFlags &= ~(COLFLAG_HASTYPE|COLFLAG_HASCOLL);
}
}
pColl = sqlite3ExprCollSeq(pParse, p);
if( pColl ){
assert( pTab->pIndex==0 );
sqlite3ColumnSetColl(db, pCol, pColl->zName);
}
}
pTab->szTabRow = 1; /* Any non-zero value works */
}
/*
** Given a SELECT statement, generate a Table structure that describes
** the result set of that SELECT.
*/
Table *sqlite3ResultSetOfSelect(Parse *pParse, Select *pSelect, char aff){
Table *pTab;
sqlite3 *db = pParse->db;
u64 savedFlags;
savedFlags = db->flags;
db->flags &= ~(u64)SQLITE_FullColNames;
db->flags |= SQLITE_ShortColNames;
sqlite3SelectPrep(pParse, pSelect, 0);
db->flags = savedFlags;
if( pParse->nErr ) return 0;
while( pSelect->pPrior ) pSelect = pSelect->pPrior;
pTab = sqlite3DbMallocZero(db, sizeof(Table) );
if( pTab==0 ){
return 0;
}
pTab->nTabRef = 1;
pTab->zName = 0;
pTab->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) );
sqlite3ColumnsFromExprList(pParse, pSelect->pEList, &pTab->nCol, &pTab->aCol);
sqlite3SubqueryColumnTypes(pParse, pTab, pSelect, aff);
pTab->iPKey = -1;
if( db->mallocFailed ){
sqlite3DeleteTable(db, pTab);
return 0;
}
return pTab;
}
/*
** Get a VDBE for the given parser context. Create a new one if necessary.
** If an error occurs, return NULL and leave a message in pParse.
*/
Vdbe *sqlite3GetVdbe(Parse *pParse){
if( pParse->pVdbe ){
return pParse->pVdbe;
}
if( pParse->pToplevel==0
&& OptimizationEnabled(pParse->db,SQLITE_FactorOutConst)
){
pParse->okConstFactor = 1;
}
return sqlite3VdbeCreate(pParse);
}
/*
** Compute the iLimit and iOffset fields of the SELECT based on the
** pLimit expressions. pLimit->pLeft and pLimit->pRight hold the expressions
** that appear in the original SQL statement after the LIMIT and OFFSET
** keywords. Or NULL if those keywords are omitted. iLimit and iOffset
** are the integer memory register numbers for counters used to compute
** the limit and offset. If there is no limit and/or offset, then
** iLimit and iOffset are negative.
**
** This routine changes the values of iLimit and iOffset only if
** a limit or offset is defined by pLimit->pLeft and pLimit->pRight. iLimit
** and iOffset should have been preset to appropriate default values (zero)
** prior to calling this routine.
**
** The iOffset register (if it exists) is initialized to the value
** of the OFFSET. The iLimit register is initialized to LIMIT. Register
** iOffset+1 is initialized to LIMIT+OFFSET.
**
** Only if pLimit->pLeft!=0 do the limit registers get
** redefined. The UNION ALL operator uses this property to force
** the reuse of the same limit and offset registers across multiple
** SELECT statements.
*/
static void computeLimitRegisters(Parse *pParse, Select *p, int iBreak){
Vdbe *v = 0;
int iLimit = 0;
int iOffset;
int n;
Expr *pLimit = p->pLimit;
if( p->iLimit ) return;
/*
** "LIMIT -1" always shows all rows. There is some
** controversy about what the correct behavior should be.
** The current implementation interprets "LIMIT 0" to mean
** no rows.
*/
if( pLimit ){
assert( pLimit->op==TK_LIMIT );
assert( pLimit->pLeft!=0 );
p->iLimit = iLimit = ++pParse->nMem;
v = sqlite3GetVdbe(pParse);
assert( v!=0 );
if( sqlite3ExprIsInteger(pLimit->pLeft, &n) ){
sqlite3VdbeAddOp2(v, OP_Integer, n, iLimit);
VdbeComment((v, "LIMIT counter"));
if( n==0 ){
sqlite3VdbeGoto(v, iBreak);
}else if( n>=0 && p->nSelectRow>sqlite3LogEst((u64)n) ){
p->nSelectRow = sqlite3LogEst((u64)n);
p->selFlags |= SF_FixedLimit;
}
}else{
sqlite3ExprCode(pParse, pLimit->pLeft, iLimit);
sqlite3VdbeAddOp1(v, OP_MustBeInt, iLimit); VdbeCoverage(v);
VdbeComment((v, "LIMIT counter"));
sqlite3VdbeAddOp2(v, OP_IfNot, iLimit, iBreak); VdbeCoverage(v);
}
if( pLimit->pRight ){
p->iOffset = iOffset = ++pParse->nMem;
pParse->nMem++; /* Allocate an extra register for limit+offset */
sqlite3ExprCode(pParse, pLimit->pRight, iOffset);
sqlite3VdbeAddOp1(v, OP_MustBeInt, iOffset); VdbeCoverage(v);
VdbeComment((v, "OFFSET counter"));
sqlite3VdbeAddOp3(v, OP_OffsetLimit, iLimit, iOffset+1, iOffset);
VdbeComment((v, "LIMIT+OFFSET"));
}
}
}
#ifndef SQLITE_OMIT_COMPOUND_SELECT
/*
** Return the appropriate collating sequence for the iCol-th column of
** the result set for the compound-select statement "p". Return NULL if
** the column has no default collating sequence.
**
** The collating sequence for the compound select is taken from the
** left-most term of the select that has a collating sequence.
*/
static CollSeq *multiSelectCollSeq(Parse *pParse, Select *p, int iCol){
CollSeq *pRet;
if( p->pPrior ){
pRet = multiSelectCollSeq(pParse, p->pPrior, iCol);
}else{
pRet = 0;
}
assert( iCol>=0 );
/* iCol must be less than p->pEList->nExpr. Otherwise an error would
** have been thrown during name resolution and we would not have gotten
** this far */
if( pRet==0 && ALWAYS(iCol<p->pEList->nExpr) ){
pRet = sqlite3ExprCollSeq(pParse, p->pEList->a[iCol].pExpr);
}
return pRet;
}
/*
** The select statement passed as the second parameter is a compound SELECT
** with an ORDER BY clause. This function allocates and returns a KeyInfo
** structure suitable for implementing the ORDER BY.
**
** Space to hold the KeyInfo structure is obtained from malloc. The calling
** function is responsible for ensuring that this structure is eventually
** freed.
*/
static KeyInfo *multiSelectOrderByKeyInfo(Parse *pParse, Select *p, int nExtra){
ExprList *pOrderBy = p->pOrderBy;
int nOrderBy = ALWAYS(pOrderBy!=0) ? pOrderBy->nExpr : 0;
sqlite3 *db = pParse->db;
KeyInfo *pRet = sqlite3KeyInfoAlloc(db, nOrderBy+nExtra, 1);
if( pRet ){
int i;
for(i=0; i<nOrderBy; i++){
struct ExprList_item *pItem = &pOrderBy->a[i];
Expr *pTerm = pItem->pExpr;
CollSeq *pColl;
if( pTerm->flags & EP_Collate ){
pColl = sqlite3ExprCollSeq(pParse, pTerm);
}else{
pColl = multiSelectCollSeq(pParse, p, pItem->u.x.iOrderByCol-1);
if( pColl==0 ) pColl = db->pDfltColl;
pOrderBy->a[i].pExpr =
sqlite3ExprAddCollateString(pParse, pTerm, pColl->zName);
}
assert( sqlite3KeyInfoIsWriteable(pRet) );
pRet->aColl[i] = pColl;
pRet->aSortFlags[i] = pOrderBy->a[i].fg.sortFlags;
}
}
return pRet;
}
#ifndef SQLITE_OMIT_CTE
/*
** This routine generates VDBE code to compute the content of a WITH RECURSIVE
** query of the form:
**
** <recursive-table> AS (<setup-query> UNION [ALL] <recursive-query>)
** \___________/ \_______________/
** p->pPrior p
**
**
** There is exactly one reference to the recursive-table in the FROM clause
** of recursive-query, marked with the SrcList->a[].fg.isRecursive flag.
**
** The setup-query runs once to generate an initial set of rows that go
** into a Queue table. Rows are extracted from the Queue table one by
** one. Each row extracted from Queue is output to pDest. Then the single
** extracted row (now in the iCurrent table) becomes the content of the
** recursive-table for a recursive-query run. The output of the recursive-query
** is added back into the Queue table. Then another row is extracted from Queue
** and the iteration continues until the Queue table is empty.
**
** If the compound query operator is UNION then no duplicate rows are ever
** inserted into the Queue table. The iDistinct table keeps a copy of all rows
** that have ever been inserted into Queue and causes duplicates to be
** discarded. If the operator is UNION ALL, then duplicates are allowed.
**
** If the query has an ORDER BY, then entries in the Queue table are kept in
** ORDER BY order and the first entry is extracted for each cycle. Without
** an ORDER BY, the Queue table is just a FIFO.
**
** If a LIMIT clause is provided, then the iteration stops after LIMIT rows
** have been output to pDest. A LIMIT of zero means to output no rows and a
** negative LIMIT means to output all rows. If there is also an OFFSET clause
** with a positive value, then the first OFFSET outputs are discarded rather
** than being sent to pDest. The LIMIT count does not begin until after OFFSET
** rows have been skipped.
*/
static void generateWithRecursiveQuery(
Parse *pParse, /* Parsing context */
Select *p, /* The recursive SELECT to be coded */
SelectDest *pDest /* What to do with query results */
){
SrcList *pSrc = p->pSrc; /* The FROM clause of the recursive query */
int nCol = p->pEList->nExpr; /* Number of columns in the recursive table */
Vdbe *v = pParse->pVdbe; /* The prepared statement under construction */
Select *pSetup; /* The setup query */
Select *pFirstRec; /* Left-most recursive term */
int addrTop; /* Top of the loop */
int addrCont, addrBreak; /* CONTINUE and BREAK addresses */
int iCurrent = 0; /* The Current table */
int regCurrent; /* Register holding Current table */
int iQueue; /* The Queue table */
int iDistinct = 0; /* To ensure unique results if UNION */
int eDest = SRT_Fifo; /* How to write to Queue */
SelectDest destQueue; /* SelectDest targetting the Queue table */
int i; /* Loop counter */
int rc; /* Result code */
ExprList *pOrderBy; /* The ORDER BY clause */
Expr *pLimit; /* Saved LIMIT and OFFSET */
int regLimit, regOffset; /* Registers used by LIMIT and OFFSET */
#ifndef SQLITE_OMIT_WINDOWFUNC
if( p->pWin ){
sqlite3ErrorMsg(pParse, "cannot use window functions in recursive queries");
return;
}
#endif
/* Obtain authorization to do a recursive query */
if( sqlite3AuthCheck(pParse, SQLITE_RECURSIVE, 0, 0, 0) ) return;
/* Process the LIMIT and OFFSET clauses, if they exist */
addrBreak = sqlite3VdbeMakeLabel(pParse);
p->nSelectRow = 320; /* 4 billion rows */
computeLimitRegisters(pParse, p, addrBreak);
pLimit = p->pLimit;
regLimit = p->iLimit;
regOffset = p->iOffset;
p->pLimit = 0;
p->iLimit = p->iOffset = 0;
pOrderBy = p->pOrderBy;
/* Locate the cursor number of the Current table */
for(i=0; ALWAYS(i<pSrc->nSrc); i++){
if( pSrc->a[i].fg.isRecursive ){
iCurrent = pSrc->a[i].iCursor;
break;
}
}
/* Allocate cursors numbers for Queue and Distinct. The cursor number for
** the Distinct table must be exactly one greater than Queue in order
** for the SRT_DistFifo and SRT_DistQueue destinations to work. */
iQueue = pParse->nTab++;
if( p->op==TK_UNION ){
eDest = pOrderBy ? SRT_DistQueue : SRT_DistFifo;
iDistinct = pParse->nTab++;
}else{
eDest = pOrderBy ? SRT_Queue : SRT_Fifo;
}
sqlite3SelectDestInit(&destQueue, eDest, iQueue);
/* Allocate cursors for Current, Queue, and Distinct. */
regCurrent = ++pParse->nMem;
sqlite3VdbeAddOp3(v, OP_OpenPseudo, iCurrent, regCurrent, nCol);
if( pOrderBy ){
KeyInfo *pKeyInfo = multiSelectOrderByKeyInfo(pParse, p, 1);
sqlite3VdbeAddOp4(v, OP_OpenEphemeral, iQueue, pOrderBy->nExpr+2, 0,
(char*)pKeyInfo, P4_KEYINFO);
destQueue.pOrderBy = pOrderBy;
}else{
sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iQueue, nCol);
}
VdbeComment((v, "Queue table"));
if( iDistinct ){
p->addrOpenEphm[0] = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iDistinct, 0);
p->selFlags |= SF_UsesEphemeral;
}
/* Detach the ORDER BY clause from the compound SELECT */
p->pOrderBy = 0;
/* Figure out how many elements of the compound SELECT are part of the
** recursive query. Make sure no recursive elements use aggregate
** functions. Mark the recursive elements as UNION ALL even if they
** are really UNION because the distinctness will be enforced by the
** iDistinct table. pFirstRec is left pointing to the left-most
** recursive term of the CTE.
*/
for(pFirstRec=p; ALWAYS(pFirstRec!=0); pFirstRec=pFirstRec->pPrior){
if( pFirstRec->selFlags & SF_Aggregate ){
sqlite3ErrorMsg(pParse, "recursive aggregate queries not supported");
goto end_of_recursive_query;
}
pFirstRec->op = TK_ALL;
if( (pFirstRec->pPrior->selFlags & SF_Recursive)==0 ) break;
}
/* Store the results of the setup-query in Queue. */
pSetup = pFirstRec->pPrior;
pSetup->pNext = 0;
ExplainQueryPlan((pParse, 1, "SETUP"));
rc = sqlite3Select(pParse, pSetup, &destQueue);
pSetup->pNext = p;
if( rc ) goto end_of_recursive_query;
/* Find the next row in the Queue and output that row */
addrTop = sqlite3VdbeAddOp2(v, OP_Rewind, iQueue, addrBreak); VdbeCoverage(v);
/* Transfer the next row in Queue over to Current */
sqlite3VdbeAddOp1(v, OP_NullRow, iCurrent); /* To reset column cache */
if( pOrderBy ){
sqlite3VdbeAddOp3(v, OP_Column, iQueue, pOrderBy->nExpr+1, regCurrent);
}else{
sqlite3VdbeAddOp2(v, OP_RowData, iQueue, regCurrent);
}
sqlite3VdbeAddOp1(v, OP_Delete, iQueue);
/* Output the single row in Current */
addrCont = sqlite3VdbeMakeLabel(pParse);
codeOffset(v, regOffset, addrCont);
selectInnerLoop(pParse, p, iCurrent,
0, 0, pDest, addrCont, addrBreak);
if( regLimit ){
sqlite3VdbeAddOp2(v, OP_DecrJumpZero, regLimit, addrBreak);
VdbeCoverage(v);
}
sqlite3VdbeResolveLabel(v, addrCont);
/* Execute the recursive SELECT taking the single row in Current as
** the value for the recursive-table. Store the results in the Queue.
*/
pFirstRec->pPrior = 0;
ExplainQueryPlan((pParse, 1, "RECURSIVE STEP"));
sqlite3Select(pParse, p, &destQueue);
assert( pFirstRec->pPrior==0 );
pFirstRec->pPrior = pSetup;
/* Keep running the loop until the Queue is empty */
sqlite3VdbeGoto(v, addrTop);
sqlite3VdbeResolveLabel(v, addrBreak);
end_of_recursive_query:
sqlite3ExprListDelete(pParse->db, p->pOrderBy);
p->pOrderBy = pOrderBy;
p->pLimit = pLimit;
return;
}
#endif /* SQLITE_OMIT_CTE */
/* Forward references */
static int multiSelectOrderBy(
Parse *pParse, /* Parsing context */
Select *p, /* The right-most of SELECTs to be coded */
SelectDest *pDest /* What to do with query results */
);
/*
** Handle the special case of a compound-select that originates from a
** VALUES clause. By handling this as a special case, we avoid deep
** recursion, and thus do not need to enforce the SQLITE_LIMIT_COMPOUND_SELECT
** on a VALUES clause.
**
** Because the Select object originates from a VALUES clause:
** (1) There is no LIMIT or OFFSET or else there is a LIMIT of exactly 1
** (2) All terms are UNION ALL
** (3) There is no ORDER BY clause
**
** The "LIMIT of exactly 1" case of condition (1) comes about when a VALUES
** clause occurs within scalar expression (ex: "SELECT (VALUES(1),(2),(3))").
** The sqlite3CodeSubselect will have added the LIMIT 1 clause in tht case.
** Since the limit is exactly 1, we only need to evaluate the left-most VALUES.
*/
static int multiSelectValues(
Parse *pParse, /* Parsing context */
Select *p, /* The right-most of SELECTs to be coded */
SelectDest *pDest /* What to do with query results */
){
int nRow = 1;
int rc = 0;
int bShowAll = p->pLimit==0;
assert( p->selFlags & SF_MultiValue );
do{
assert( p->selFlags & SF_Values );
assert( p->op==TK_ALL || (p->op==TK_SELECT && p->pPrior==0) );
assert( p->pNext==0 || p->pEList->nExpr==p->pNext->pEList->nExpr );
#ifndef SQLITE_OMIT_WINDOWFUNC
if( p->pWin ) return -1;
#endif
if( p->pPrior==0 ) break;
assert( p->pPrior->pNext==p );
p = p->pPrior;
nRow += bShowAll;
}while(1);
ExplainQueryPlan((pParse, 0, "SCAN %d CONSTANT ROW%s", nRow,
nRow==1 ? "" : "S"));
while( p ){
selectInnerLoop(pParse, p, -1, 0, 0, pDest, 1, 1);
if( !bShowAll ) break;
p->nSelectRow = nRow;
p = p->pNext;
}
return rc;
}
/*
** Return true if the SELECT statement which is known to be the recursive
** part of a recursive CTE still has its anchor terms attached. If the
** anchor terms have already been removed, then return false.
*/
static int hasAnchor(Select *p){
while( p && (p->selFlags & SF_Recursive)!=0 ){ p = p->pPrior; }
return p!=0;
}
/*
** This routine is called to process a compound query form from
** two or more separate queries using UNION, UNION ALL, EXCEPT, or
** INTERSECT
**
** "p" points to the right-most of the two queries. the query on the
** left is p->pPrior. The left query could also be a compound query
** in which case this routine will be called recursively.
**
** The results of the total query are to be written into a destination
** of type eDest with parameter iParm.
**
** Example 1: Consider a three-way compound SQL statement.
**
** SELECT a FROM t1 UNION SELECT b FROM t2 UNION SELECT c FROM t3
**
** This statement is parsed up as follows:
**
** SELECT c FROM t3
** |
** `-----> SELECT b FROM t2
** |
** `------> SELECT a FROM t1
**
** The arrows in the diagram above represent the Select.pPrior pointer.
** So if this routine is called with p equal to the t3 query, then
** pPrior will be the t2 query. p->op will be TK_UNION in this case.
**
** Notice that because of the way SQLite parses compound SELECTs, the
** individual selects always group from left to right.
*/
static int multiSelect(
Parse *pParse, /* Parsing context */
Select *p, /* The right-most of SELECTs to be coded */
SelectDest *pDest /* What to do with query results */
){
int rc = SQLITE_OK; /* Success code from a subroutine */
Select *pPrior; /* Another SELECT immediately to our left */
Vdbe *v; /* Generate code to this VDBE */
SelectDest dest; /* Alternative data destination */
Select *pDelete = 0; /* Chain of simple selects to delete */
sqlite3 *db; /* Database connection */
/* Make sure there is no ORDER BY or LIMIT clause on prior SELECTs. Only
** the last (right-most) SELECT in the series may have an ORDER BY or LIMIT.
*/
assert( p && p->pPrior ); /* Calling function guarantees this much */
assert( (p->selFlags & SF_Recursive)==0 || p->op==TK_ALL || p->op==TK_UNION );
assert( p->selFlags & SF_Compound );
db = pParse->db;
pPrior = p->pPrior;
dest = *pDest;
assert( pPrior->pOrderBy==0 );
assert( pPrior->pLimit==0 );
v = sqlite3GetVdbe(pParse);
assert( v!=0 ); /* The VDBE already created by calling function */
/* Create the destination temporary table if necessary
*/
if( dest.eDest==SRT_EphemTab ){
assert( p->pEList );
sqlite3VdbeAddOp2(v, OP_OpenEphemeral, dest.iSDParm, p->pEList->nExpr);
dest.eDest = SRT_Table;
}
/* Special handling for a compound-select that originates as a VALUES clause.
*/
if( p->selFlags & SF_MultiValue ){
rc = multiSelectValues(pParse, p, &dest);
if( rc>=0 ) goto multi_select_end;
rc = SQLITE_OK;
}
/* Make sure all SELECTs in the statement have the same number of elements
** in their result sets.
*/
assert( p->pEList && pPrior->pEList );
assert( p->pEList->nExpr==pPrior->pEList->nExpr );
#ifndef SQLITE_OMIT_CTE
if( (p->selFlags & SF_Recursive)!=0 && hasAnchor(p) ){
generateWithRecursiveQuery(pParse, p, &dest);
}else
#endif
/* Compound SELECTs that have an ORDER BY clause are handled separately.
*/
if( p->pOrderBy ){
return multiSelectOrderBy(pParse, p, pDest);
}else{
#ifndef SQLITE_OMIT_EXPLAIN
if( pPrior->pPrior==0 ){
ExplainQueryPlan((pParse, 1, "COMPOUND QUERY"));
ExplainQueryPlan((pParse, 1, "LEFT-MOST SUBQUERY"));
}
#endif
/* Generate code for the left and right SELECT statements.
*/
switch( p->op ){
case TK_ALL: {
int addr = 0;
int nLimit = 0; /* Initialize to suppress harmless compiler warning */
assert( !pPrior->pLimit );
pPrior->iLimit = p->iLimit;
pPrior->iOffset = p->iOffset;
pPrior->pLimit = p->pLimit;
TREETRACE(0x200, pParse, p, ("multiSelect UNION ALL left...\n"));
rc = sqlite3Select(pParse, pPrior, &dest);
pPrior->pLimit = 0;
if( rc ){
goto multi_select_end;
}
p->pPrior = 0;
p->iLimit = pPrior->iLimit;
p->iOffset = pPrior->iOffset;
if( p->iLimit ){
addr = sqlite3VdbeAddOp1(v, OP_IfNot, p->iLimit); VdbeCoverage(v);
VdbeComment((v, "Jump ahead if LIMIT reached"));
if( p->iOffset ){
sqlite3VdbeAddOp3(v, OP_OffsetLimit,
p->iLimit, p->iOffset+1, p->iOffset);
}
}
ExplainQueryPlan((pParse, 1, "UNION ALL"));
TREETRACE(0x200, pParse, p, ("multiSelect UNION ALL right...\n"));
rc = sqlite3Select(pParse, p, &dest);
testcase( rc!=SQLITE_OK );
pDelete = p->pPrior;
p->pPrior = pPrior;
p->nSelectRow = sqlite3LogEstAdd(p->nSelectRow, pPrior->nSelectRow);
if( p->pLimit
&& sqlite3ExprIsInteger(p->pLimit->pLeft, &nLimit)
&& nLimit>0 && p->nSelectRow > sqlite3LogEst((u64)nLimit)
){
p->nSelectRow = sqlite3LogEst((u64)nLimit);
}
if( addr ){
sqlite3VdbeJumpHere(v, addr);
}
break;
}
case TK_EXCEPT:
case TK_UNION: {
int unionTab; /* Cursor number of the temp table holding result */
u8 op = 0; /* One of the SRT_ operations to apply to self */
int priorOp; /* The SRT_ operation to apply to prior selects */
Expr *pLimit; /* Saved values of p->nLimit */
int addr;
SelectDest uniondest;
testcase( p->op==TK_EXCEPT );
testcase( p->op==TK_UNION );
priorOp = SRT_Union;
if( dest.eDest==priorOp ){
/* We can reuse a temporary table generated by a SELECT to our
** right.
*/
assert( p->pLimit==0 ); /* Not allowed on leftward elements */
unionTab = dest.iSDParm;
}else{
/* We will need to create our own temporary table to hold the
** intermediate results.
*/
unionTab = pParse->nTab++;
assert( p->pOrderBy==0 );
addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, unionTab, 0);
assert( p->addrOpenEphm[0] == -1 );
p->addrOpenEphm[0] = addr;
findRightmost(p)->selFlags |= SF_UsesEphemeral;
assert( p->pEList );
}
/* Code the SELECT statements to our left
*/
assert( !pPrior->pOrderBy );
sqlite3SelectDestInit(&uniondest, priorOp, unionTab);
TREETRACE(0x200, pParse, p, ("multiSelect EXCEPT/UNION left...\n"));
rc = sqlite3Select(pParse, pPrior, &uniondest);
if( rc ){
goto multi_select_end;
}
/* Code the current SELECT statement
*/
if( p->op==TK_EXCEPT ){
op = SRT_Except;
}else{
assert( p->op==TK_UNION );
op = SRT_Union;
}
p->pPrior = 0;
pLimit = p->pLimit;
p->pLimit = 0;
uniondest.eDest = op;
ExplainQueryPlan((pParse, 1, "%s USING TEMP B-TREE",
sqlite3SelectOpName(p->op)));
TREETRACE(0x200, pParse, p, ("multiSelect EXCEPT/UNION right...\n"));
rc = sqlite3Select(pParse, p, &uniondest);
testcase( rc!=SQLITE_OK );
assert( p->pOrderBy==0 );
pDelete = p->pPrior;
p->pPrior = pPrior;
p->pOrderBy = 0;
if( p->op==TK_UNION ){
p->nSelectRow = sqlite3LogEstAdd(p->nSelectRow, pPrior->nSelectRow);
}
sqlite3ExprDelete(db, p->pLimit);
p->pLimit = pLimit;
p->iLimit = 0;
p->iOffset = 0;
/* Convert the data in the temporary table into whatever form
** it is that we currently need.
*/
assert( unionTab==dest.iSDParm || dest.eDest!=priorOp );
assert( p->pEList || db->mallocFailed );
if( dest.eDest!=priorOp && db->mallocFailed==0 ){
int iCont, iBreak, iStart;
iBreak = sqlite3VdbeMakeLabel(pParse);
iCont = sqlite3VdbeMakeLabel(pParse);
computeLimitRegisters(pParse, p, iBreak);
sqlite3VdbeAddOp2(v, OP_Rewind, unionTab, iBreak); VdbeCoverage(v);
iStart = sqlite3VdbeCurrentAddr(v);
selectInnerLoop(pParse, p, unionTab,
0, 0, &dest, iCont, iBreak);
sqlite3VdbeResolveLabel(v, iCont);
sqlite3VdbeAddOp2(v, OP_Next, unionTab, iStart); VdbeCoverage(v);
sqlite3VdbeResolveLabel(v, iBreak);
sqlite3VdbeAddOp2(v, OP_Close, unionTab, 0);
}
break;
}
default: assert( p->op==TK_INTERSECT ); {
int tab1, tab2;
int iCont, iBreak, iStart;
Expr *pLimit;
int addr;
SelectDest intersectdest;
int r1;
/* INTERSECT is different from the others since it requires
** two temporary tables. Hence it has its own case. Begin
** by allocating the tables we will need.
*/
tab1 = pParse->nTab++;
tab2 = pParse->nTab++;
assert( p->pOrderBy==0 );
addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab1, 0);
assert( p->addrOpenEphm[0] == -1 );
p->addrOpenEphm[0] = addr;
findRightmost(p)->selFlags |= SF_UsesEphemeral;
assert( p->pEList );
/* Code the SELECTs to our left into temporary table "tab1".
*/
sqlite3SelectDestInit(&intersectdest, SRT_Union, tab1);
TREETRACE(0x400, pParse, p, ("multiSelect INTERSECT left...\n"));
rc = sqlite3Select(pParse, pPrior, &intersectdest);
if( rc ){
goto multi_select_end;
}
/* Code the current SELECT into temporary table "tab2"
*/
addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab2, 0);
assert( p->addrOpenEphm[1] == -1 );
p->addrOpenEphm[1] = addr;
p->pPrior = 0;
pLimit = p->pLimit;
p->pLimit = 0;
intersectdest.iSDParm = tab2;
ExplainQueryPlan((pParse, 1, "%s USING TEMP B-TREE",
sqlite3SelectOpName(p->op)));
TREETRACE(0x400, pParse, p, ("multiSelect INTERSECT right...\n"));
rc = sqlite3Select(pParse, p, &intersectdest);
testcase( rc!=SQLITE_OK );
pDelete = p->pPrior;
p->pPrior = pPrior;
if( p->nSelectRow>pPrior->nSelectRow ){
p->nSelectRow = pPrior->nSelectRow;
}
sqlite3ExprDelete(db, p->pLimit);
p->pLimit = pLimit;
/* Generate code to take the intersection of the two temporary
** tables.
*/
if( rc ) break;
assert( p->pEList );
iBreak = sqlite3VdbeMakeLabel(pParse);
iCont = sqlite3VdbeMakeLabel(pParse);
computeLimitRegisters(pParse, p, iBreak);
sqlite3VdbeAddOp2(v, OP_Rewind, tab1, iBreak); VdbeCoverage(v);
r1 = sqlite3GetTempReg(pParse);
iStart = sqlite3VdbeAddOp2(v, OP_RowData, tab1, r1);
sqlite3VdbeAddOp4Int(v, OP_NotFound, tab2, iCont, r1, 0);
VdbeCoverage(v);
sqlite3ReleaseTempReg(pParse, r1);
selectInnerLoop(pParse, p, tab1,
0, 0, &dest, iCont, iBreak);
sqlite3VdbeResolveLabel(v, iCont);
sqlite3VdbeAddOp2(v, OP_Next, tab1, iStart); VdbeCoverage(v);
sqlite3VdbeResolveLabel(v, iBreak);
sqlite3VdbeAddOp2(v, OP_Close, tab2, 0);
sqlite3VdbeAddOp2(v, OP_Close, tab1, 0);
break;
}
}
#ifndef SQLITE_OMIT_EXPLAIN
if( p->pNext==0 ){
ExplainQueryPlanPop(pParse);
}
#endif
}
if( pParse->nErr ) goto multi_select_end;
/* Compute collating sequences used by
** temporary tables needed to implement the compound select.
** Attach the KeyInfo structure to all temporary tables.
**
** This section is run by the right-most SELECT statement only.
** SELECT statements to the left always skip this part. The right-most
** SELECT might also skip this part if it has no ORDER BY clause and
** no temp tables are required.
*/
if( p->selFlags & SF_UsesEphemeral ){
int i; /* Loop counter */
KeyInfo *pKeyInfo; /* Collating sequence for the result set */
Select *pLoop; /* For looping through SELECT statements */
CollSeq **apColl; /* For looping through pKeyInfo->aColl[] */
int nCol; /* Number of columns in result set */
assert( p->pNext==0 );
assert( p->pEList!=0 );
nCol = p->pEList->nExpr;
pKeyInfo = sqlite3KeyInfoAlloc(db, nCol, 1);
if( !pKeyInfo ){
rc = SQLITE_NOMEM_BKPT;
goto multi_select_end;
}
for(i=0, apColl=pKeyInfo->aColl; i<nCol; i++, apColl++){
*apColl = multiSelectCollSeq(pParse, p, i);
if( 0==*apColl ){
*apColl = db->pDfltColl;
}
}
for(pLoop=p; pLoop; pLoop=pLoop->pPrior){
for(i=0; i<2; i++){
int addr = pLoop->addrOpenEphm[i];
if( addr<0 ){
/* If [0] is unused then [1] is also unused. So we can
** always safely abort as soon as the first unused slot is found */
assert( pLoop->addrOpenEphm[1]<0 );
break;
}
sqlite3VdbeChangeP2(v, addr, nCol);
sqlite3VdbeChangeP4(v, addr, (char*)sqlite3KeyInfoRef(pKeyInfo),
P4_KEYINFO);
pLoop->addrOpenEphm[i] = -1;
}
}
sqlite3KeyInfoUnref(pKeyInfo);
}
multi_select_end:
pDest->iSdst = dest.iSdst;
pDest->nSdst = dest.nSdst;
if( pDelete ){
sqlite3ParserAddCleanup(pParse,
(void(*)(sqlite3*,void*))sqlite3SelectDelete,
pDelete);
}
return rc;
}
#endif /* SQLITE_OMIT_COMPOUND_SELECT */
/*
** Error message for when two or more terms of a compound select have different
** size result sets.
*/
void sqlite3SelectWrongNumTermsError(Parse *pParse, Select *p){
if( p->selFlags & SF_Values ){
sqlite3ErrorMsg(pParse, "all VALUES must have the same number of terms");
}else{
sqlite3ErrorMsg(pParse, "SELECTs to the left and right of %s"
" do not have the same number of result columns",
sqlite3SelectOpName(p->op));
}
}
/*
** Code an output subroutine for a coroutine implementation of a
** SELECT statment.
**
** The data to be output is contained in pIn->iSdst. There are
** pIn->nSdst columns to be output. pDest is where the output should
** be sent.
**
** regReturn is the number of the register holding the subroutine
** return address.
**
** If regPrev>0 then it is the first register in a vector that
** records the previous output. mem[regPrev] is a flag that is false
** if there has been no previous output. If regPrev>0 then code is
** generated to suppress duplicates. pKeyInfo is used for comparing
** keys.
**
** If the LIMIT found in p->iLimit is reached, jump immediately to
** iBreak.
*/
static int generateOutputSubroutine(
Parse *pParse, /* Parsing context */
Select *p, /* The SELECT statement */
SelectDest *pIn, /* Coroutine supplying data */
SelectDest *pDest, /* Where to send the data */
int regReturn, /* The return address register */
int regPrev, /* Previous result register. No uniqueness if 0 */
KeyInfo *pKeyInfo, /* For comparing with previous entry */
int iBreak /* Jump here if we hit the LIMIT */
){
Vdbe *v = pParse->pVdbe;
int iContinue;
int addr;
addr = sqlite3VdbeCurrentAddr(v);
iContinue = sqlite3VdbeMakeLabel(pParse);
/* Suppress duplicates for UNION, EXCEPT, and INTERSECT
*/
if( regPrev ){
int addr1, addr2;
addr1 = sqlite3VdbeAddOp1(v, OP_IfNot, regPrev); VdbeCoverage(v);
addr2 = sqlite3VdbeAddOp4(v, OP_Compare, pIn->iSdst, regPrev+1, pIn->nSdst,
(char*)sqlite3KeyInfoRef(pKeyInfo), P4_KEYINFO);
sqlite3VdbeAddOp3(v, OP_Jump, addr2+2, iContinue, addr2+2); VdbeCoverage(v);
sqlite3VdbeJumpHere(v, addr1);
sqlite3VdbeAddOp3(v, OP_Copy, pIn->iSdst, regPrev+1, pIn->nSdst-1);
sqlite3VdbeAddOp2(v, OP_Integer, 1, regPrev);
}
if( pParse->db->mallocFailed ) return 0;
/* Suppress the first OFFSET entries if there is an OFFSET clause
*/
codeOffset(v, p->iOffset, iContinue);
assert( pDest->eDest!=SRT_Exists );
assert( pDest->eDest!=SRT_Table );
switch( pDest->eDest ){
/* Store the result as data using a unique key.
*/
case SRT_EphemTab: {
int r1 = sqlite3GetTempReg(pParse);
int r2 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_MakeRecord, pIn->iSdst, pIn->nSdst, r1);
sqlite3VdbeAddOp2(v, OP_NewRowid, pDest->iSDParm, r2);
sqlite3VdbeAddOp3(v, OP_Insert, pDest->iSDParm, r1, r2);
sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
sqlite3ReleaseTempReg(pParse, r2);
sqlite3ReleaseTempReg(pParse, r1);
break;
}
#ifndef SQLITE_OMIT_SUBQUERY
/* If we are creating a set for an "expr IN (SELECT ...)".
*/
case SRT_Set: {
int r1;
testcase( pIn->nSdst>1 );
r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp4(v, OP_MakeRecord, pIn->iSdst, pIn->nSdst,
r1, pDest->zAffSdst, pIn->nSdst);
sqlite3VdbeAddOp4Int(v, OP_IdxInsert, pDest->iSDParm, r1,
pIn->iSdst, pIn->nSdst);
sqlite3ReleaseTempReg(pParse, r1);
break;
}
/* If this is a scalar select that is part of an expression, then
** store the results in the appropriate memory cell and break out
** of the scan loop. Note that the select might return multiple columns
** if it is the RHS of a row-value IN operator.
*/
case SRT_Mem: {
testcase( pIn->nSdst>1 );
sqlite3ExprCodeMove(pParse, pIn->iSdst, pDest->iSDParm, pIn->nSdst);
/* The LIMIT clause will jump out of the loop for us */
break;
}
#endif /* #ifndef SQLITE_OMIT_SUBQUERY */
/* The results are stored in a sequence of registers
** starting at pDest->iSdst. Then the co-routine yields.
*/
case SRT_Coroutine: {
if( pDest->iSdst==0 ){
pDest->iSdst = sqlite3GetTempRange(pParse, pIn->nSdst);
pDest->nSdst = pIn->nSdst;
}
sqlite3ExprCodeMove(pParse, pIn->iSdst, pDest->iSdst, pIn->nSdst);
sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm);
break;
}
/* If none of the above, then the result destination must be
** SRT_Output. This routine is never called with any other
** destination other than the ones handled above or SRT_Output.
**
** For SRT_Output, results are stored in a sequence of registers.
** Then the OP_ResultRow opcode is used to cause sqlite3_step() to
** return the next row of result.
*/
default: {
assert( pDest->eDest==SRT_Output );
sqlite3VdbeAddOp2(v, OP_ResultRow, pIn->iSdst, pIn->nSdst);
break;
}
}
/* Jump to the end of the loop if the LIMIT is reached.
*/
if( p->iLimit ){
sqlite3VdbeAddOp2(v, OP_DecrJumpZero, p->iLimit, iBreak); VdbeCoverage(v);
}
/* Generate the subroutine return
*/
sqlite3VdbeResolveLabel(v, iContinue);
sqlite3VdbeAddOp1(v, OP_Return, regReturn);
return addr;
}
/*
** Alternative compound select code generator for cases when there
** is an ORDER BY clause.
**
** We assume a query of the following form:
**
** <selectA> <operator> <selectB> ORDER BY <orderbylist>
**
** <operator> is one of UNION ALL, UNION, EXCEPT, or INTERSECT. The idea
** is to code both <selectA> and <selectB> with the ORDER BY clause as
** co-routines. Then run the co-routines in parallel and merge the results
** into the output. In addition to the two coroutines (called selectA and
** selectB) there are 7 subroutines:
**
** outA: Move the output of the selectA coroutine into the output
** of the compound query.
**
** outB: Move the output of the selectB coroutine into the output
** of the compound query. (Only generated for UNION and
** UNION ALL. EXCEPT and INSERTSECT never output a row that
** appears only in B.)
**
** AltB: Called when there is data from both coroutines and A<B.
**
** AeqB: Called when there is data from both coroutines and A==B.
**
** AgtB: Called when there is data from both coroutines and A>B.
**
** EofA: Called when data is exhausted from selectA.
**
** EofB: Called when data is exhausted from selectB.
**
** The implementation of the latter five subroutines depend on which
** <operator> is used:
**
**
** UNION ALL UNION EXCEPT INTERSECT
** ------------- ----------------- -------------- -----------------
** AltB: outA, nextA outA, nextA outA, nextA nextA
**
** AeqB: outA, nextA nextA nextA outA, nextA
**
** AgtB: outB, nextB outB, nextB nextB nextB
**
** EofA: outB, nextB outB, nextB halt halt
**
** EofB: outA, nextA outA, nextA outA, nextA halt
**
** In the AltB, AeqB, and AgtB subroutines, an EOF on A following nextA
** causes an immediate jump to EofA and an EOF on B following nextB causes
** an immediate jump to EofB. Within EofA and EofB, and EOF on entry or
** following nextX causes a jump to the end of the select processing.
**
** Duplicate removal in the UNION, EXCEPT, and INTERSECT cases is handled
** within the output subroutine. The regPrev register set holds the previously
** output value. A comparison is made against this value and the output
** is skipped if the next results would be the same as the previous.
**
** The implementation plan is to implement the two coroutines and seven
** subroutines first, then put the control logic at the bottom. Like this:
**
** goto Init
** coA: coroutine for left query (A)
** coB: coroutine for right query (B)
** outA: output one row of A
** outB: output one row of B (UNION and UNION ALL only)
** EofA: ...
** EofB: ...
** AltB: ...
** AeqB: ...
** AgtB: ...
** Init: initialize coroutine registers
** yield coA
** if eof(A) goto EofA
** yield coB
** if eof(B) goto EofB
** Cmpr: Compare A, B
** Jump AltB, AeqB, AgtB
** End: ...
**
** We call AltB, AeqB, AgtB, EofA, and EofB "subroutines" but they are not
** actually called using Gosub and they do not Return. EofA and EofB loop
** until all data is exhausted then jump to the "end" labe. AltB, AeqB,
** and AgtB jump to either L2 or to one of EofA or EofB.
*/
#ifndef SQLITE_OMIT_COMPOUND_SELECT
static int multiSelectOrderBy(
Parse *pParse, /* Parsing context */
Select *p, /* The right-most of SELECTs to be coded */
SelectDest *pDest /* What to do with query results */
){
int i, j; /* Loop counters */
Select *pPrior; /* Another SELECT immediately to our left */
Select *pSplit; /* Left-most SELECT in the right-hand group */
int nSelect; /* Number of SELECT statements in the compound */
Vdbe *v; /* Generate code to this VDBE */
SelectDest destA; /* Destination for coroutine A */
SelectDest destB; /* Destination for coroutine B */
int regAddrA; /* Address register for select-A coroutine */
int regAddrB; /* Address register for select-B coroutine */
int addrSelectA; /* Address of the select-A coroutine */
int addrSelectB; /* Address of the select-B coroutine */
int regOutA; /* Address register for the output-A subroutine */
int regOutB; /* Address register for the output-B subroutine */
int addrOutA; /* Address of the output-A subroutine */
int addrOutB = 0; /* Address of the output-B subroutine */
int addrEofA; /* Address of the select-A-exhausted subroutine */
int addrEofA_noB; /* Alternate addrEofA if B is uninitialized */
int addrEofB; /* Address of the select-B-exhausted subroutine */
int addrAltB; /* Address of the A<B subroutine */
int addrAeqB; /* Address of the A==B subroutine */
int addrAgtB; /* Address of the A>B subroutine */
int regLimitA; /* Limit register for select-A */
int regLimitB; /* Limit register for select-A */
int regPrev; /* A range of registers to hold previous output */
int savedLimit; /* Saved value of p->iLimit */
int savedOffset; /* Saved value of p->iOffset */
int labelCmpr; /* Label for the start of the merge algorithm */
int labelEnd; /* Label for the end of the overall SELECT stmt */
int addr1; /* Jump instructions that get retargetted */
int op; /* One of TK_ALL, TK_UNION, TK_EXCEPT, TK_INTERSECT */
KeyInfo *pKeyDup = 0; /* Comparison information for duplicate removal */
KeyInfo *pKeyMerge; /* Comparison information for merging rows */
sqlite3 *db; /* Database connection */
ExprList *pOrderBy; /* The ORDER BY clause */
int nOrderBy; /* Number of terms in the ORDER BY clause */
u32 *aPermute; /* Mapping from ORDER BY terms to result set columns */
assert( p->pOrderBy!=0 );
assert( pKeyDup==0 ); /* "Managed" code needs this. Ticket #3382. */
db = pParse->db;
v = pParse->pVdbe;
assert( v!=0 ); /* Already thrown the error if VDBE alloc failed */
labelEnd = sqlite3VdbeMakeLabel(pParse);
labelCmpr = sqlite3VdbeMakeLabel(pParse);
/* Patch up the ORDER BY clause
*/
op = p->op;
assert( p->pPrior->pOrderBy==0 );
pOrderBy = p->pOrderBy;
assert( pOrderBy );
nOrderBy = pOrderBy->nExpr;
/* For operators other than UNION ALL we have to make sure that
** the ORDER BY clause covers every term of the result set. Add
** terms to the ORDER BY clause as necessary.
*/
if( op!=TK_ALL ){
for(i=1; db->mallocFailed==0 && i<=p->pEList->nExpr; i++){
struct ExprList_item *pItem;
for(j=0, pItem=pOrderBy->a; j<nOrderBy; j++, pItem++){
assert( pItem!=0 );
assert( pItem->u.x.iOrderByCol>0 );
if( pItem->u.x.iOrderByCol==i ) break;
}
if( j==nOrderBy ){
Expr *pNew = sqlite3Expr(db, TK_INTEGER, 0);
if( pNew==0 ) return SQLITE_NOMEM_BKPT;
pNew->flags |= EP_IntValue;
pNew->u.iValue = i;
p->pOrderBy = pOrderBy = sqlite3ExprListAppend(pParse, pOrderBy, pNew);
if( pOrderBy ) pOrderBy->a[nOrderBy++].u.x.iOrderByCol = (u16)i;
}
}
}
/* Compute the comparison permutation and keyinfo that is used with
** the permutation used to determine if the next
** row of results comes from selectA or selectB. Also add explicit
** collations to the ORDER BY clause terms so that when the subqueries
** to the right and the left are evaluated, they use the correct
** collation.
*/
aPermute = sqlite3DbMallocRawNN(db, sizeof(u32)*(nOrderBy + 1));
if( aPermute ){
struct ExprList_item *pItem;
aPermute[0] = nOrderBy;
for(i=1, pItem=pOrderBy->a; i<=nOrderBy; i++, pItem++){
assert( pItem!=0 );
assert( pItem->u.x.iOrderByCol>0 );
assert( pItem->u.x.iOrderByCol<=p->pEList->nExpr );
aPermute[i] = pItem->u.x.iOrderByCol - 1;
}
pKeyMerge = multiSelectOrderByKeyInfo(pParse, p, 1);
}else{
pKeyMerge = 0;
}
/* Allocate a range of temporary registers and the KeyInfo needed
** for the logic that removes duplicate result rows when the
** operator is UNION, EXCEPT, or INTERSECT (but not UNION ALL).
*/
if( op==TK_ALL ){
regPrev = 0;
}else{
int nExpr = p->pEList->nExpr;
assert( nOrderBy>=nExpr || db->mallocFailed );
regPrev = pParse->nMem+1;
pParse->nMem += nExpr+1;
sqlite3VdbeAddOp2(v, OP_Integer, 0, regPrev);
pKeyDup = sqlite3KeyInfoAlloc(db, nExpr, 1);
if( pKeyDup ){
assert( sqlite3KeyInfoIsWriteable(pKeyDup) );
for(i=0; i<nExpr; i++){
pKeyDup->aColl[i] = multiSelectCollSeq(pParse, p, i);
pKeyDup->aSortFlags[i] = 0;
}
}
}
/* Separate the left and the right query from one another
*/
nSelect = 1;
if( (op==TK_ALL || op==TK_UNION)
&& OptimizationEnabled(db, SQLITE_BalancedMerge)
){
for(pSplit=p; pSplit->pPrior!=0 && pSplit->op==op; pSplit=pSplit->pPrior){
nSelect++;
assert( pSplit->pPrior->pNext==pSplit );
}
}
if( nSelect<=3 ){
pSplit = p;
}else{
pSplit = p;
for(i=2; i<nSelect; i+=2){ pSplit = pSplit->pPrior; }
}
pPrior = pSplit->pPrior;
assert( pPrior!=0 );
pSplit->pPrior = 0;
pPrior->pNext = 0;
assert( p->pOrderBy == pOrderBy );
assert( pOrderBy!=0 || db->mallocFailed );
pPrior->pOrderBy = sqlite3ExprListDup(pParse->db, pOrderBy, 0);
sqlite3ResolveOrderGroupBy(pParse, p, p->pOrderBy, "ORDER");
sqlite3ResolveOrderGroupBy(pParse, pPrior, pPrior->pOrderBy, "ORDER");
/* Compute the limit registers */
computeLimitRegisters(pParse, p, labelEnd);
if( p->iLimit && op==TK_ALL ){
regLimitA = ++pParse->nMem;
regLimitB = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Copy, p->iOffset ? p->iOffset+1 : p->iLimit,
regLimitA);
sqlite3VdbeAddOp2(v, OP_Copy, regLimitA, regLimitB);
}else{
regLimitA = regLimitB = 0;
}
sqlite3ExprDelete(db, p->pLimit);
p->pLimit = 0;
regAddrA = ++pParse->nMem;
regAddrB = ++pParse->nMem;
regOutA = ++pParse->nMem;
regOutB = ++pParse->nMem;
sqlite3SelectDestInit(&destA, SRT_Coroutine, regAddrA);
sqlite3SelectDestInit(&destB, SRT_Coroutine, regAddrB);
ExplainQueryPlan((pParse, 1, "MERGE (%s)", sqlite3SelectOpName(p->op)));
/* Generate a coroutine to evaluate the SELECT statement to the
** left of the compound operator - the "A" select.
*/
addrSelectA = sqlite3VdbeCurrentAddr(v) + 1;
addr1 = sqlite3VdbeAddOp3(v, OP_InitCoroutine, regAddrA, 0, addrSelectA);
VdbeComment((v, "left SELECT"));
pPrior->iLimit = regLimitA;
ExplainQueryPlan((pParse, 1, "LEFT"));
sqlite3Select(pParse, pPrior, &destA);
sqlite3VdbeEndCoroutine(v, regAddrA);
sqlite3VdbeJumpHere(v, addr1);
/* Generate a coroutine to evaluate the SELECT statement on
** the right - the "B" select
*/
addrSelectB = sqlite3VdbeCurrentAddr(v) + 1;
addr1 = sqlite3VdbeAddOp3(v, OP_InitCoroutine, regAddrB, 0, addrSelectB);
VdbeComment((v, "right SELECT"));
savedLimit = p->iLimit;
savedOffset = p->iOffset;
p->iLimit = regLimitB;
p->iOffset = 0;
ExplainQueryPlan((pParse, 1, "RIGHT"));
sqlite3Select(pParse, p, &destB);
p->iLimit = savedLimit;
p->iOffset = savedOffset;
sqlite3VdbeEndCoroutine(v, regAddrB);
/* Generate a subroutine that outputs the current row of the A
** select as the next output row of the compound select.
*/
VdbeNoopComment((v, "Output routine for A"));
addrOutA = generateOutputSubroutine(pParse,
p, &destA, pDest, regOutA,
regPrev, pKeyDup, labelEnd);
/* Generate a subroutine that outputs the current row of the B
** select as the next output row of the compound select.
*/
if( op==TK_ALL || op==TK_UNION ){
VdbeNoopComment((v, "Output routine for B"));
addrOutB = generateOutputSubroutine(pParse,
p, &destB, pDest, regOutB,
regPrev, pKeyDup, labelEnd);
}
sqlite3KeyInfoUnref(pKeyDup);
/* Generate a subroutine to run when the results from select A
** are exhausted and only data in select B remains.
*/
if( op==TK_EXCEPT || op==TK_INTERSECT ){
addrEofA_noB = addrEofA = labelEnd;
}else{
VdbeNoopComment((v, "eof-A subroutine"));
addrEofA = sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB);
addrEofA_noB = sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, labelEnd);
VdbeCoverage(v);
sqlite3VdbeGoto(v, addrEofA);
p->nSelectRow = sqlite3LogEstAdd(p->nSelectRow, pPrior->nSelectRow);
}
/* Generate a subroutine to run when the results from select B
** are exhausted and only data in select A remains.
*/
if( op==TK_INTERSECT ){
addrEofB = addrEofA;
if( p->nSelectRow > pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow;
}else{
VdbeNoopComment((v, "eof-B subroutine"));
addrEofB = sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA);
sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, labelEnd); VdbeCoverage(v);
sqlite3VdbeGoto(v, addrEofB);
}
/* Generate code to handle the case of A<B
*/
VdbeNoopComment((v, "A-lt-B subroutine"));
addrAltB = sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA);
sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, addrEofA); VdbeCoverage(v);
sqlite3VdbeGoto(v, labelCmpr);
/* Generate code to handle the case of A==B
*/
if( op==TK_ALL ){
addrAeqB = addrAltB;
}else if( op==TK_INTERSECT ){
addrAeqB = addrAltB;
addrAltB++;
}else{
VdbeNoopComment((v, "A-eq-B subroutine"));
addrAeqB =
sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, addrEofA); VdbeCoverage(v);
sqlite3VdbeGoto(v, labelCmpr);
}
/* Generate code to handle the case of A>B
*/
VdbeNoopComment((v, "A-gt-B subroutine"));
addrAgtB = sqlite3VdbeCurrentAddr(v);
if( op==TK_ALL || op==TK_UNION ){
sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB);
}
sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, addrEofB); VdbeCoverage(v);
sqlite3VdbeGoto(v, labelCmpr);
/* This code runs once to initialize everything.
*/
sqlite3VdbeJumpHere(v, addr1);
sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, addrEofA_noB); VdbeCoverage(v);
sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, addrEofB); VdbeCoverage(v);
/* Implement the main merge loop
*/
sqlite3VdbeResolveLabel(v, labelCmpr);
sqlite3VdbeAddOp4(v, OP_Permutation, 0, 0, 0, (char*)aPermute, P4_INTARRAY);
sqlite3VdbeAddOp4(v, OP_Compare, destA.iSdst, destB.iSdst, nOrderBy,
(char*)pKeyMerge, P4_KEYINFO);
sqlite3VdbeChangeP5(v, OPFLAG_PERMUTE);
sqlite3VdbeAddOp3(v, OP_Jump, addrAltB, addrAeqB, addrAgtB); VdbeCoverage(v);
/* Jump to the this point in order to terminate the query.
*/
sqlite3VdbeResolveLabel(v, labelEnd);
/* Make arrangements to free the 2nd and subsequent arms of the compound
** after the parse has finished */
if( pSplit->pPrior ){
sqlite3ParserAddCleanup(pParse,
(void(*)(sqlite3*,void*))sqlite3SelectDelete, pSplit->pPrior);
}
pSplit->pPrior = pPrior;
pPrior->pNext = pSplit;
sqlite3ExprListDelete(db, pPrior->pOrderBy);
pPrior->pOrderBy = 0;
/*** TBD: Insert subroutine calls to close cursors on incomplete
**** subqueries ****/
ExplainQueryPlanPop(pParse);
return pParse->nErr!=0;
}
#endif
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
/* An instance of the SubstContext object describes an substitution edit
** to be performed on a parse tree.
**
** All references to columns in table iTable are to be replaced by corresponding
** expressions in pEList.
**
** ## About "isOuterJoin":
**
** The isOuterJoin column indicates that the replacement will occur into a
** position in the parent that NULL-able due to an OUTER JOIN. Either the
** target slot in the parent is the right operand of a LEFT JOIN, or one of
** the left operands of a RIGHT JOIN. In either case, we need to potentially
** bypass the substituted expression with OP_IfNullRow.
**
** Suppose the original expression is an integer constant. Even though the table
** has the nullRow flag set, because the expression is an integer constant,
** it will not be NULLed out. So instead, we insert an OP_IfNullRow opcode
** that checks to see if the nullRow flag is set on the table. If the nullRow
** flag is set, then the value in the register is set to NULL and the original
** expression is bypassed. If the nullRow flag is not set, then the original
** expression runs to populate the register.
**
** Example where this is needed:
**
** CREATE TABLE t1(a INTEGER PRIMARY KEY, b INT);
** CREATE TABLE t2(x INT UNIQUE);
**
** SELECT a,b,m,x FROM t1 LEFT JOIN (SELECT 59 AS m,x FROM t2) ON b=x;
**
** When the subquery on the right side of the LEFT JOIN is flattened, we
** have to add OP_IfNullRow in front of the OP_Integer that implements the
** "m" value of the subquery so that a NULL will be loaded instead of 59
** when processing a non-matched row of the left.
*/
typedef struct SubstContext {
Parse *pParse; /* The parsing context */
int iTable; /* Replace references to this table */
int iNewTable; /* New table number */
int isOuterJoin; /* Add TK_IF_NULL_ROW opcodes on each replacement */
ExprList *pEList; /* Replacement expressions */
ExprList *pCList; /* Collation sequences for replacement expr */
} SubstContext;
/* Forward Declarations */
static void substExprList(SubstContext*, ExprList*);
static void substSelect(SubstContext*, Select*, int);
/*
** Scan through the expression pExpr. Replace every reference to
** a column in table number iTable with a copy of the iColumn-th
** entry in pEList. (But leave references to the ROWID column
** unchanged.)
**
** This routine is part of the flattening procedure. A subquery
** whose result set is defined by pEList appears as entry in the
** FROM clause of a SELECT such that the VDBE cursor assigned to that
** FORM clause entry is iTable. This routine makes the necessary
** changes to pExpr so that it refers directly to the source table
** of the subquery rather the result set of the subquery.
*/
static Expr *substExpr(
SubstContext *pSubst, /* Description of the substitution */
Expr *pExpr /* Expr in which substitution occurs */
){
if( pExpr==0 ) return 0;
if( ExprHasProperty(pExpr, EP_OuterON|EP_InnerON)
&& pExpr->w.iJoin==pSubst->iTable
){
testcase( ExprHasProperty(pExpr, EP_InnerON) );
pExpr->w.iJoin = pSubst->iNewTable;
}
if( pExpr->op==TK_COLUMN
&& pExpr->iTable==pSubst->iTable
&& !ExprHasProperty(pExpr, EP_FixedCol)
){
#ifdef SQLITE_ALLOW_ROWID_IN_VIEW
if( pExpr->iColumn<0 ){
pExpr->op = TK_NULL;
}else
#endif
{
Expr *pNew;
int iColumn = pExpr->iColumn;
Expr *pCopy = pSubst->pEList->a[iColumn].pExpr;
Expr ifNullRow;
assert( pSubst->pEList!=0 && iColumn<pSubst->pEList->nExpr );
assert( pExpr->pRight==0 );
if( sqlite3ExprIsVector(pCopy) ){
sqlite3VectorErrorMsg(pSubst->pParse, pCopy);
}else{
sqlite3 *db = pSubst->pParse->db;
if( pSubst->isOuterJoin && pCopy->op!=TK_COLUMN ){
memset(&ifNullRow, 0, sizeof(ifNullRow));
ifNullRow.op = TK_IF_NULL_ROW;
ifNullRow.pLeft = pCopy;
ifNullRow.iTable = pSubst->iNewTable;
ifNullRow.iColumn = -99;
ifNullRow.flags = EP_IfNullRow;
pCopy = &ifNullRow;
}
testcase( ExprHasProperty(pCopy, EP_Subquery) );
pNew = sqlite3ExprDup(db, pCopy, 0);
if( db->mallocFailed ){
sqlite3ExprDelete(db, pNew);
return pExpr;
}
if( pSubst->isOuterJoin ){
ExprSetProperty(pNew, EP_CanBeNull);
}
if( ExprHasProperty(pExpr,EP_OuterON|EP_InnerON) ){
sqlite3SetJoinExpr(pNew, pExpr->w.iJoin,
pExpr->flags & (EP_OuterON|EP_InnerON));
}
sqlite3ExprDelete(db, pExpr);
pExpr = pNew;
if( pExpr->op==TK_TRUEFALSE ){
pExpr->u.iValue = sqlite3ExprTruthValue(pExpr);
pExpr->op = TK_INTEGER;
ExprSetProperty(pExpr, EP_IntValue);
}
/* Ensure that the expression now has an implicit collation sequence,
** just as it did when it was a column of a view or sub-query. */
{
CollSeq *pNat = sqlite3ExprCollSeq(pSubst->pParse, pExpr);
CollSeq *pColl = sqlite3ExprCollSeq(pSubst->pParse,
pSubst->pCList->a[iColumn].pExpr
);
if( pNat!=pColl || (pExpr->op!=TK_COLUMN && pExpr->op!=TK_COLLATE) ){
pExpr = sqlite3ExprAddCollateString(pSubst->pParse, pExpr,
(pColl ? pColl->zName : "BINARY")
);
}
}
ExprClearProperty(pExpr, EP_Collate);
}
}
}else{
if( pExpr->op==TK_IF_NULL_ROW && pExpr->iTable==pSubst->iTable ){
pExpr->iTable = pSubst->iNewTable;
}
pExpr->pLeft = substExpr(pSubst, pExpr->pLeft);
pExpr->pRight = substExpr(pSubst, pExpr->pRight);
if( ExprUseXSelect(pExpr) ){
substSelect(pSubst, pExpr->x.pSelect, 1);
}else{
substExprList(pSubst, pExpr->x.pList);
}
#ifndef SQLITE_OMIT_WINDOWFUNC
if( ExprHasProperty(pExpr, EP_WinFunc) ){
Window *pWin = pExpr->y.pWin;
pWin->pFilter = substExpr(pSubst, pWin->pFilter);
substExprList(pSubst, pWin->pPartition);
substExprList(pSubst, pWin->pOrderBy);
}
#endif
}
return pExpr;
}
static void substExprList(
SubstContext *pSubst, /* Description of the substitution */
ExprList *pList /* List to scan and in which to make substitutes */
){
int i;
if( pList==0 ) return;
for(i=0; i<pList->nExpr; i++){
pList->a[i].pExpr = substExpr(pSubst, pList->a[i].pExpr);
}
}
static void substSelect(
SubstContext *pSubst, /* Description of the substitution */
Select *p, /* SELECT statement in which to make substitutions */
int doPrior /* Do substitutes on p->pPrior too */
){
SrcList *pSrc;
SrcItem *pItem;
int i;
if( !p ) return;
do{
substExprList(pSubst, p->pEList);
substExprList(pSubst, p->pGroupBy);
substExprList(pSubst, p->pOrderBy);
p->pHaving = substExpr(pSubst, p->pHaving);
p->pWhere = substExpr(pSubst, p->pWhere);
pSrc = p->pSrc;
assert( pSrc!=0 );
for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){
substSelect(pSubst, pItem->pSelect, 1);
if( pItem->fg.isTabFunc ){
substExprList(pSubst, pItem->u1.pFuncArg);
}
}
}while( doPrior && (p = p->pPrior)!=0 );
}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
/*
** pSelect is a SELECT statement and pSrcItem is one item in the FROM
** clause of that SELECT.
**
** This routine scans the entire SELECT statement and recomputes the
** pSrcItem->colUsed mask.
*/
static int recomputeColumnsUsedExpr(Walker *pWalker, Expr *pExpr){
SrcItem *pItem;
if( pExpr->op!=TK_COLUMN ) return WRC_Continue;
pItem = pWalker->u.pSrcItem;
if( pItem->iCursor!=pExpr->iTable ) return WRC_Continue;
if( pExpr->iColumn<0 ) return WRC_Continue;
pItem->colUsed |= sqlite3ExprColUsed(pExpr);
return WRC_Continue;
}
static void recomputeColumnsUsed(
Select *pSelect, /* The complete SELECT statement */
SrcItem *pSrcItem /* Which FROM clause item to recompute */
){
Walker w;
if( NEVER(pSrcItem->pTab==0) ) return;
memset(&w, 0, sizeof(w));
w.xExprCallback = recomputeColumnsUsedExpr;
w.xSelectCallback = sqlite3SelectWalkNoop;
w.u.pSrcItem = pSrcItem;
pSrcItem->colUsed = 0;
sqlite3WalkSelect(&w, pSelect);
}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
/*
** Assign new cursor numbers to each of the items in pSrc. For each
** new cursor number assigned, set an entry in the aCsrMap[] array
** to map the old cursor number to the new:
**
** aCsrMap[iOld+1] = iNew;
**
** The array is guaranteed by the caller to be large enough for all
** existing cursor numbers in pSrc. aCsrMap[0] is the array size.
**
** If pSrc contains any sub-selects, call this routine recursively
** on the FROM clause of each such sub-select, with iExcept set to -1.
*/
static void srclistRenumberCursors(
Parse *pParse, /* Parse context */
int *aCsrMap, /* Array to store cursor mappings in */
SrcList *pSrc, /* FROM clause to renumber */
int iExcept /* FROM clause item to skip */
){
int i;
SrcItem *pItem;
for(i=0, pItem=pSrc->a; i<pSrc->nSrc; i++, pItem++){
if( i!=iExcept ){
Select *p;
assert( pItem->iCursor < aCsrMap[0] );
if( !pItem->fg.isRecursive || aCsrMap[pItem->iCursor+1]==0 ){
aCsrMap[pItem->iCursor+1] = pParse->nTab++;
}
pItem->iCursor = aCsrMap[pItem->iCursor+1];
for(p=pItem->pSelect; p; p=p->pPrior){
srclistRenumberCursors(pParse, aCsrMap, p->pSrc, -1);
}
}
}
}
/*
** *piCursor is a cursor number. Change it if it needs to be mapped.
*/
static void renumberCursorDoMapping(Walker *pWalker, int *piCursor){
int *aCsrMap = pWalker->u.aiCol;
int iCsr = *piCursor;
if( iCsr < aCsrMap[0] && aCsrMap[iCsr+1]>0 ){
*piCursor = aCsrMap[iCsr+1];
}
}
/*
** Expression walker callback used by renumberCursors() to update
** Expr objects to match newly assigned cursor numbers.
*/
static int renumberCursorsCb(Walker *pWalker, Expr *pExpr){
int op = pExpr->op;
if( op==TK_COLUMN || op==TK_IF_NULL_ROW ){
renumberCursorDoMapping(pWalker, &pExpr->iTable);
}
if( ExprHasProperty(pExpr, EP_OuterON) ){
renumberCursorDoMapping(pWalker, &pExpr->w.iJoin);
}
return WRC_Continue;
}
/*
** Assign a new cursor number to each cursor in the FROM clause (Select.pSrc)
** of the SELECT statement passed as the second argument, and to each
** cursor in the FROM clause of any FROM clause sub-selects, recursively.
** Except, do not assign a new cursor number to the iExcept'th element in
** the FROM clause of (*p). Update all expressions and other references
** to refer to the new cursor numbers.
**
** Argument aCsrMap is an array that may be used for temporary working
** space. Two guarantees are made by the caller:
**
** * the array is larger than the largest cursor number used within the
** select statement passed as an argument, and
**
** * the array entries for all cursor numbers that do *not* appear in
** FROM clauses of the select statement as described above are
** initialized to zero.
*/
static void renumberCursors(
Parse *pParse, /* Parse context */
Select *p, /* Select to renumber cursors within */
int iExcept, /* FROM clause item to skip */
int *aCsrMap /* Working space */
){
Walker w;
srclistRenumberCursors(pParse, aCsrMap, p->pSrc, iExcept);
memset(&w, 0, sizeof(w));
w.u.aiCol = aCsrMap;
w.xExprCallback = renumberCursorsCb;
w.xSelectCallback = sqlite3SelectWalkNoop;
sqlite3WalkSelect(&w, p);
}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
/*
** If pSel is not part of a compound SELECT, return a pointer to its
** expression list. Otherwise, return a pointer to the expression list
** of the leftmost SELECT in the compound.
*/
static ExprList *findLeftmostExprlist(Select *pSel){
while( pSel->pPrior ){
pSel = pSel->pPrior;
}
return pSel->pEList;
}
/*
** Return true if any of the result-set columns in the compound query
** have incompatible affinities on one or more arms of the compound.
*/
static int compoundHasDifferentAffinities(Select *p){
int ii;
ExprList *pList;
assert( p!=0 );
assert( p->pEList!=0 );
assert( p->pPrior!=0 );
pList = p->pEList;
for(ii=0; ii<pList->nExpr; ii++){
char aff;
Select *pSub1;
assert( pList->a[ii].pExpr!=0 );
aff = sqlite3ExprAffinity(pList->a[ii].pExpr);
for(pSub1=p->pPrior; pSub1; pSub1=pSub1->pPrior){
assert( pSub1->pEList!=0 );
assert( pSub1->pEList->nExpr>ii );
assert( pSub1->pEList->a[ii].pExpr!=0 );
if( sqlite3ExprAffinity(pSub1->pEList->a[ii].pExpr)!=aff ){
return 1;
}
}
}
return 0;
}
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
/*
** This routine attempts to flatten subqueries as a performance optimization.
** This routine returns 1 if it makes changes and 0 if no flattening occurs.
**
** To understand the concept of flattening, consider the following
** query:
**
** SELECT a FROM (SELECT x+y AS a FROM t1 WHERE z<100) WHERE a>5
**
** The default way of implementing this query is to execute the
** subquery first and store the results in a temporary table, then
** run the outer query on that temporary table. This requires two
** passes over the data. Furthermore, because the temporary table
** has no indices, the WHERE clause on the outer query cannot be
** optimized.
**
** This routine attempts to rewrite queries such as the above into
** a single flat select, like this:
**
** SELECT x+y AS a FROM t1 WHERE z<100 AND a>5
**
** The code generated for this simplification gives the same result
** but only has to scan the data once. And because indices might
** exist on the table t1, a complete scan of the data might be
** avoided.
**
** Flattening is subject to the following constraints:
**
** (**) We no longer attempt to flatten aggregate subqueries. Was:
** The subquery and the outer query cannot both be aggregates.
**
** (**) We no longer attempt to flatten aggregate subqueries. Was:
** (2) If the subquery is an aggregate then
** (2a) the outer query must not be a join and
** (2b) the outer query must not use subqueries
** other than the one FROM-clause subquery that is a candidate
** for flattening. (This is due to ticket [2f7170d73bf9abf80]
** from 2015-02-09.)
**
** (3) If the subquery is the right operand of a LEFT JOIN then
** (3a) the subquery may not be a join and
** (3b) the FROM clause of the subquery may not contain a virtual
** table and
** (**) Was: "The outer query may not have a GROUP BY." This case
** is now managed correctly
** (3d) the outer query may not be DISTINCT.
** See also (26) for restrictions on RIGHT JOIN.
**
** (4) The subquery can not be DISTINCT.
**
** (**) At one point restrictions (4) and (5) defined a subset of DISTINCT
** sub-queries that were excluded from this optimization. Restriction
** (4) has since been expanded to exclude all DISTINCT subqueries.
**
** (**) We no longer attempt to flatten aggregate subqueries. Was:
** If the subquery is aggregate, the outer query may not be DISTINCT.
**
** (7) The subquery must have a FROM clause. TODO: For subqueries without
** A FROM clause, consider adding a FROM clause with the special
** table sqlite_once that consists of a single row containing a
** single NULL.
**
** (8) If the subquery uses LIMIT then the outer query may not be a join.
**
** (9) If the subquery uses LIMIT then the outer query may not be aggregate.
**
** (**) Restriction (10) was removed from the code on 2005-02-05 but we
** accidently carried the comment forward until 2014-09-15. Original
** constraint: "If the subquery is aggregate then the outer query
** may not use LIMIT."
**
** (11) The subquery and the outer query may not both have ORDER BY clauses.
**
** (**) Not implemented. Subsumed into restriction (3). Was previously
** a separate restriction deriving from ticket #350.
**
** (13) The subquery and outer query may not both use LIMIT.
**
** (14) The subquery may not use OFFSET.
**
** (15) If the outer query is part of a compound select, then the
** subquery may not use LIMIT.
** (See ticket #2339 and ticket [02a8e81d44]).
**
** (16) If the outer query is aggregate, then the subquery may not
** use ORDER BY. (Ticket #2942) This used to not matter
** until we introduced the group_concat() function.
**
** (17) If the subquery is a compound select, then
** (17a) all compound operators must be a UNION ALL, and
** (17b) no terms within the subquery compound may be aggregate
** or DISTINCT, and
** (17c) every term within the subquery compound must have a FROM clause
** (17d) the outer query may not be
** (17d1) aggregate, or
** (17d2) DISTINCT
** (17e) the subquery may not contain window functions, and
** (17f) the subquery must not be the RHS of a LEFT JOIN.
** (17g) either the subquery is the first element of the outer
** query or there are no RIGHT or FULL JOINs in any arm
** of the subquery. (This is a duplicate of condition (27b).)
** (17h) The corresponding result set expressions in all arms of the
** compound must have the same affinity. (See restriction (9)
** on the push-down optimization.)
**
** The parent and sub-query may contain WHERE clauses. Subject to
** rules (11), (13) and (14), they may also contain ORDER BY,
** LIMIT and OFFSET clauses. The subquery cannot use any compound
** operator other than UNION ALL because all the other compound
** operators have an implied DISTINCT which is disallowed by
** restriction (4).
**
** Also, each component of the sub-query must return the same number
** of result columns. This is actually a requirement for any compound
** SELECT statement, but all the code here does is make sure that no
** such (illegal) sub-query is flattened. The caller will detect the
** syntax error and return a detailed message.
**
** (18) If the sub-query is a compound select, then all terms of the
** ORDER BY clause of the parent must be copies of a term returned
** by the parent query.
**
** (19) If the subquery uses LIMIT then the outer query may not
** have a WHERE clause.
**
** (20) If the sub-query is a compound select, then it must not use
** an ORDER BY clause. Ticket #3773. We could relax this constraint
** somewhat by saying that the terms of the ORDER BY clause must
** appear as unmodified result columns in the outer query. But we
** have other optimizations in mind to deal with that case.
**
** (21) If the subquery uses LIMIT then the outer query may not be
** DISTINCT. (See ticket [752e1646fc]).
**
** (22) The subquery may not be a recursive CTE.
**
** (23) If the outer query is a recursive CTE, then the sub-query may not be
** a compound query. This restriction is because transforming the
** parent to a compound query confuses the code that handles
** recursive queries in multiSelect().
**
** (**) We no longer attempt to flatten aggregate subqueries. Was:
** The subquery may not be an aggregate that uses the built-in min() or
** or max() functions. (Without this restriction, a query like:
** "SELECT x FROM (SELECT max(y), x FROM t1)" would not necessarily
** return the value X for which Y was maximal.)
**
** (25) If either the subquery or the parent query contains a window
** function in the select list or ORDER BY clause, flattening
** is not attempted.
**
** (26) The subquery may not be the right operand of a RIGHT JOIN.
** See also (3) for restrictions on LEFT JOIN.
**
** (27) The subquery may not contain a FULL or RIGHT JOIN unless it
** is the first element of the parent query. Two subcases:
** (27a) the subquery is not a compound query.
** (27b) the subquery is a compound query and the RIGHT JOIN occurs
** in any arm of the compound query. (See also (17g).)
**
** (28) The subquery is not a MATERIALIZED CTE.
**
**
** In this routine, the "p" parameter is a pointer to the outer query.
** The subquery is p->pSrc->a[iFrom]. isAgg is true if the outer query
** uses aggregates.
**
** If flattening is not attempted, this routine is a no-op and returns 0.
** If flattening is attempted this routine returns 1.
**
** All of the expression analysis must occur on both the outer query and
** the subquery before this routine runs.
*/
static int flattenSubquery(
Parse *pParse, /* Parsing context */
Select *p, /* The parent or outer SELECT statement */
int iFrom, /* Index in p->pSrc->a[] of the inner subquery */
int isAgg /* True if outer SELECT uses aggregate functions */
){
const char *zSavedAuthContext = pParse->zAuthContext;
Select *pParent; /* Current UNION ALL term of the other query */
Select *pSub; /* The inner query or "subquery" */
Select *pSub1; /* Pointer to the rightmost select in sub-query */
SrcList *pSrc; /* The FROM clause of the outer query */
SrcList *pSubSrc; /* The FROM clause of the subquery */
int iParent; /* VDBE cursor number of the pSub result set temp table */
int iNewParent = -1;/* Replacement table for iParent */
int isOuterJoin = 0; /* True if pSub is the right side of a LEFT JOIN */
int i; /* Loop counter */
Expr *pWhere; /* The WHERE clause */
SrcItem *pSubitem; /* The subquery */
sqlite3 *db = pParse->db;
Walker w; /* Walker to persist agginfo data */
int *aCsrMap = 0;
/* Check to see if flattening is permitted. Return 0 if not.
*/
assert( p!=0 );
assert( p->pPrior==0 );
if( OptimizationDisabled(db, SQLITE_QueryFlattener) ) return 0;
pSrc = p->pSrc;
assert( pSrc && iFrom>=0 && iFrom<pSrc->nSrc );
pSubitem = &pSrc->a[iFrom];
iParent = pSubitem->iCursor;
pSub = pSubitem->pSelect;
assert( pSub!=0 );
#ifndef SQLITE_OMIT_WINDOWFUNC
if( p->pWin || pSub->pWin ) return 0; /* Restriction (25) */
#endif
pSubSrc = pSub->pSrc;
assert( pSubSrc );
/* Prior to version 3.1.2, when LIMIT and OFFSET had to be simple constants,
** not arbitrary expressions, we allowed some combining of LIMIT and OFFSET
** because they could be computed at compile-time. But when LIMIT and OFFSET
** became arbitrary expressions, we were forced to add restrictions (13)
** and (14). */
if( pSub->pLimit && p->pLimit ) return 0; /* Restriction (13) */
if( pSub->pLimit && pSub->pLimit->pRight ) return 0; /* Restriction (14) */
if( (p->selFlags & SF_Compound)!=0 && pSub->pLimit ){
return 0; /* Restriction (15) */
}
if( pSubSrc->nSrc==0 ) return 0; /* Restriction (7) */
if( pSub->selFlags & SF_Distinct ) return 0; /* Restriction (4) */
if( pSub->pLimit && (pSrc->nSrc>1 || isAgg) ){
return 0; /* Restrictions (8)(9) */
}
if( p->pOrderBy && pSub->pOrderBy ){
return 0; /* Restriction (11) */
}
if( isAgg && pSub->pOrderBy ) return 0; /* Restriction (16) */
if( pSub->pLimit && p->pWhere ) return 0; /* Restriction (19) */
if( pSub->pLimit && (p->selFlags & SF_Distinct)!=0 ){
return 0; /* Restriction (21) */
}
if( pSub->selFlags & (SF_Recursive) ){
return 0; /* Restrictions (22) */
}
/*
** If the subquery is the right operand of a LEFT JOIN, then the
** subquery may not be a join itself (3a). Example of why this is not
** allowed:
**
** t1 LEFT OUTER JOIN (t2 JOIN t3)
**
** If we flatten the above, we would get
**
** (t1 LEFT OUTER JOIN t2) JOIN t3
**
** which is not at all the same thing.
**
** See also tickets #306, #350, and #3300.
*/
if( (pSubitem->fg.jointype & (JT_OUTER|JT_LTORJ))!=0 ){
if( pSubSrc->nSrc>1 /* (3a) */
|| IsVirtual(pSubSrc->a[0].pTab) /* (3b) */
|| (p->selFlags & SF_Distinct)!=0 /* (3d) */
|| (pSubitem->fg.jointype & JT_RIGHT)!=0 /* (26) */
){
return 0;
}
isOuterJoin = 1;
}
assert( pSubSrc->nSrc>0 ); /* True by restriction (7) */
if( iFrom>0 && (pSubSrc->a[0].fg.jointype & JT_LTORJ)!=0 ){
return 0; /* Restriction (27a) */
}
if( pSubitem->fg.isCte && pSubitem->u2.pCteUse->eM10d==M10d_Yes ){
return 0; /* (28) */
}
/* Restriction (17): If the sub-query is a compound SELECT, then it must
** use only the UNION ALL operator. And none of the simple select queries
** that make up the compound SELECT are allowed to be aggregate or distinct
** queries.
*/
if( pSub->pPrior ){
int ii;
if( pSub->pOrderBy ){
return 0; /* Restriction (20) */
}
if( isAgg || (p->selFlags & SF_Distinct)!=0 || isOuterJoin>0 ){
return 0; /* (17d1), (17d2), or (17f) */
}
for(pSub1=pSub; pSub1; pSub1=pSub1->pPrior){
testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct );
testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Aggregate );
assert( pSub->pSrc!=0 );
assert( (pSub->selFlags & SF_Recursive)==0 );
assert( pSub->pEList->nExpr==pSub1->pEList->nExpr );
if( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))!=0 /* (17b) */
|| (pSub1->pPrior && pSub1->op!=TK_ALL) /* (17a) */
|| pSub1->pSrc->nSrc<1 /* (17c) */
#ifndef SQLITE_OMIT_WINDOWFUNC
|| pSub1->pWin /* (17e) */
#endif
){
return 0;
}
if( iFrom>0 && (pSub1->pSrc->a[0].fg.jointype & JT_LTORJ)!=0 ){
/* Without this restriction, the JT_LTORJ flag would end up being
** omitted on left-hand tables of the right join that is being
** flattened. */
return 0; /* Restrictions (17g), (27b) */
}
testcase( pSub1->pSrc->nSrc>1 );
}
/* Restriction (18). */
if( p->pOrderBy ){
for(ii=0; ii<p->pOrderBy->nExpr; ii++){
if( p->pOrderBy->a[ii].u.x.iOrderByCol==0 ) return 0;
}
}
/* Restriction (23) */
if( (p->selFlags & SF_Recursive) ) return 0;
/* Restriction (17h) */
if( compoundHasDifferentAffinities(pSub) ) return 0;
if( pSrc->nSrc>1 ){
if( pParse->nSelect>500 ) return 0;
if( OptimizationDisabled(db, SQLITE_FlttnUnionAll) ) return 0;
aCsrMap = sqlite3DbMallocZero(db, ((i64)pParse->nTab+1)*sizeof(int));
if( aCsrMap ) aCsrMap[0] = pParse->nTab;
}
}
/***** If we reach this point, flattening is permitted. *****/
TREETRACE(0x4,pParse,p,("flatten %u.%p from term %d\n",
pSub->selId, pSub, iFrom));
/* Authorize the subquery */
pParse->zAuthContext = pSubitem->zName;
TESTONLY(i =) sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0);
testcase( i==SQLITE_DENY );
pParse->zAuthContext = zSavedAuthContext;
/* Delete the transient structures associated with thesubquery */
pSub1 = pSubitem->pSelect;
sqlite3DbFree(db, pSubitem->zDatabase);
sqlite3DbFree(db, pSubitem->zName);
sqlite3DbFree(db, pSubitem->zAlias);
pSubitem->zDatabase = 0;
pSubitem->zName = 0;
pSubitem->zAlias = 0;
pSubitem->pSelect = 0;
assert( pSubitem->fg.isUsing!=0 || pSubitem->u3.pOn==0 );
/* If the sub-query is a compound SELECT statement, then (by restrictions
** 17 and 18 above) it must be a UNION ALL and the parent query must
** be of the form:
**
** SELECT <expr-list> FROM (<sub-query>) <where-clause>
**
** followed by any ORDER BY, LIMIT and/or OFFSET clauses. This block
** creates N-1 copies of the parent query without any ORDER BY, LIMIT or
** OFFSET clauses and joins them to the left-hand-side of the original
** using UNION ALL operators. In this case N is the number of simple
** select statements in the compound sub-query.
**
** Example:
**
** SELECT a+1 FROM (
** SELECT x FROM tab
** UNION ALL
** SELECT y FROM tab
** UNION ALL
** SELECT abs(z*2) FROM tab2
** ) WHERE a!=5 ORDER BY 1
**
** Transformed into:
**
** SELECT x+1 FROM tab WHERE x+1!=5
** UNION ALL
** SELECT y+1 FROM tab WHERE y+1!=5
** UNION ALL
** SELECT abs(z*2)+1 FROM tab2 WHERE abs(z*2)+1!=5
** ORDER BY 1
**
** We call this the "compound-subquery flattening".
*/
for(pSub=pSub->pPrior; pSub; pSub=pSub->pPrior){
Select *pNew;
ExprList *pOrderBy = p->pOrderBy;
Expr *pLimit = p->pLimit;
Select *pPrior = p->pPrior;
Table *pItemTab = pSubitem->pTab;
pSubitem->pTab = 0;
p->pOrderBy = 0;
p->pPrior = 0;
p->pLimit = 0;
pNew = sqlite3SelectDup(db, p, 0);
p->pLimit = pLimit;
p->pOrderBy = pOrderBy;
p->op = TK_ALL;
pSubitem->pTab = pItemTab;
if( pNew==0 ){
p->pPrior = pPrior;
}else{
pNew->selId = ++pParse->nSelect;
if( aCsrMap && ALWAYS(db->mallocFailed==0) ){
renumberCursors(pParse, pNew, iFrom, aCsrMap);
}
pNew->pPrior = pPrior;
if( pPrior ) pPrior->pNext = pNew;
pNew->pNext = p;
p->pPrior = pNew;
TREETRACE(0x4,pParse,p,("compound-subquery flattener"
" creates %u as peer\n",pNew->selId));
}
assert( pSubitem->pSelect==0 );
}
sqlite3DbFree(db, aCsrMap);
if( db->mallocFailed ){
pSubitem->pSelect = pSub1;
return 1;
}
/* Defer deleting the Table object associated with the
** subquery until code generation is
** complete, since there may still exist Expr.pTab entries that
** refer to the subquery even after flattening. Ticket #3346.
**
** pSubitem->pTab is always non-NULL by test restrictions and tests above.
*/
if( ALWAYS(pSubitem->pTab!=0) ){
Table *pTabToDel = pSubitem->pTab;
if( pTabToDel->nTabRef==1 ){
Parse *pToplevel = sqlite3ParseToplevel(pParse);
sqlite3ParserAddCleanup(pToplevel,
(void(*)(sqlite3*,void*))sqlite3DeleteTable,
pTabToDel);
testcase( pToplevel->earlyCleanup );
}else{
pTabToDel->nTabRef--;
}
pSubitem->pTab = 0;
}
/* The following loop runs once for each term in a compound-subquery
** flattening (as described above). If we are doing a different kind
** of flattening - a flattening other than a compound-subquery flattening -
** then this loop only runs once.
**
** This loop moves all of the FROM elements of the subquery into the
** the FROM clause of the outer query. Before doing this, remember
** the cursor number for the original outer query FROM element in
** iParent. The iParent cursor will never be used. Subsequent code
** will scan expressions looking for iParent references and replace
** those references with expressions that resolve to the subquery FROM
** elements we are now copying in.
*/
pSub = pSub1;
for(pParent=p; pParent; pParent=pParent->pPrior, pSub=pSub->pPrior){
int nSubSrc;
u8 jointype = 0;
u8 ltorj = pSrc->a[iFrom].fg.jointype & JT_LTORJ;
assert( pSub!=0 );
pSubSrc = pSub->pSrc; /* FROM clause of subquery */
nSubSrc = pSubSrc->nSrc; /* Number of terms in subquery FROM clause */
pSrc = pParent->pSrc; /* FROM clause of the outer query */
if( pParent==p ){
jointype = pSubitem->fg.jointype; /* First time through the loop */
}
/* The subquery uses a single slot of the FROM clause of the outer
** query. If the subquery has more than one element in its FROM clause,
** then expand the outer query to make space for it to hold all elements
** of the subquery.
**
** Example:
**
** SELECT * FROM tabA, (SELECT * FROM sub1, sub2), tabB;
**
** The outer query has 3 slots in its FROM clause. One slot of the
** outer query (the middle slot) is used by the subquery. The next
** block of code will expand the outer query FROM clause to 4 slots.
** The middle slot is expanded to two slots in order to make space
** for the two elements in the FROM clause of the subquery.
*/
if( nSubSrc>1 ){
pSrc = sqlite3SrcListEnlarge(pParse, pSrc, nSubSrc-1,iFrom+1);
if( pSrc==0 ) break;
pParent->pSrc = pSrc;
}
/* Transfer the FROM clause terms from the subquery into the
** outer query.
*/
for(i=0; i<nSubSrc; i++){
SrcItem *pItem = &pSrc->a[i+iFrom];
if( pItem->fg.isUsing ) sqlite3IdListDelete(db, pItem->u3.pUsing);
assert( pItem->fg.isTabFunc==0 );
*pItem = pSubSrc->a[i];
pItem->fg.jointype |= ltorj;
iNewParent = pSubSrc->a[i].iCursor;
memset(&pSubSrc->a[i], 0, sizeof(pSubSrc->a[i]));
}
pSrc->a[iFrom].fg.jointype &= JT_LTORJ;
pSrc->a[iFrom].fg.jointype |= jointype | ltorj;
/* Now begin substituting subquery result set expressions for
** references to the iParent in the outer query.
**
** Example:
**
** SELECT a+5, b*10 FROM (SELECT x*3 AS a, y+10 AS b FROM t1) WHERE a>b;
** \ \_____________ subquery __________/ /
** \_____________________ outer query ______________________________/
**
** We look at every expression in the outer query and every place we see
** "a" we substitute "x*3" and every place we see "b" we substitute "y+10".
*/
if( pSub->pOrderBy && (pParent->selFlags & SF_NoopOrderBy)==0 ){
/* At this point, any non-zero iOrderByCol values indicate that the
** ORDER BY column expression is identical to the iOrderByCol'th
** expression returned by SELECT statement pSub. Since these values
** do not necessarily correspond to columns in SELECT statement pParent,
** zero them before transfering the ORDER BY clause.
**
** Not doing this may cause an error if a subsequent call to this
** function attempts to flatten a compound sub-query into pParent
** (the only way this can happen is if the compound sub-query is
** currently part of pSub->pSrc). See ticket [d11a6e908f]. */
ExprList *pOrderBy = pSub->pOrderBy;
for(i=0; i<pOrderBy->nExpr; i++){
pOrderBy->a[i].u.x.iOrderByCol = 0;
}
assert( pParent->pOrderBy==0 );
pParent->pOrderBy = pOrderBy;
pSub->pOrderBy = 0;
}
pWhere = pSub->pWhere;
pSub->pWhere = 0;
if( isOuterJoin>0 ){
sqlite3SetJoinExpr(pWhere, iNewParent, EP_OuterON);
}
if( pWhere ){
if( pParent->pWhere ){
pParent->pWhere = sqlite3PExpr(pParse, TK_AND, pWhere, pParent->pWhere);
}else{
pParent->pWhere = pWhere;
}
}
if( db->mallocFailed==0 ){
SubstContext x;
x.pParse = pParse;
x.iTable = iParent;
x.iNewTable = iNewParent;
x.isOuterJoin = isOuterJoin;
x.pEList = pSub->pEList;
x.pCList = findLeftmostExprlist(pSub);
substSelect(&x, pParent, 0);
}
/* The flattened query is a compound if either the inner or the
** outer query is a compound. */
pParent->selFlags |= pSub->selFlags & SF_Compound;
assert( (pSub->selFlags & SF_Distinct)==0 ); /* restriction (17b) */
/*
** SELECT ... FROM (SELECT ... LIMIT a OFFSET b) LIMIT x OFFSET y;
**
** One is tempted to try to add a and b to combine the limits. But this
** does not work if either limit is negative.
*/
if( pSub->pLimit ){
pParent->pLimit = pSub->pLimit;
pSub->pLimit = 0;
}
/* Recompute the SrcItem.colUsed masks for the flattened
** tables. */
for(i=0; i<nSubSrc; i++){
recomputeColumnsUsed(pParent, &pSrc->a[i+iFrom]);
}
}
/* Finially, delete what is left of the subquery and return
** success.
*/
sqlite3AggInfoPersistWalkerInit(&w, pParse);
sqlite3WalkSelect(&w,pSub1);
sqlite3SelectDelete(db, pSub1);
#if TREETRACE_ENABLED
if( sqlite3TreeTrace & 0x4 ){
TREETRACE(0x4,pParse,p,("After flattening:\n"));
sqlite3TreeViewSelect(0, p, 0);
}
#endif
return 1;
}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
/*
** A structure to keep track of all of the column values that are fixed to
** a known value due to WHERE clause constraints of the form COLUMN=VALUE.
*/
typedef struct WhereConst WhereConst;
struct WhereConst {
Parse *pParse; /* Parsing context */
u8 *pOomFault; /* Pointer to pParse->db->mallocFailed */
int nConst; /* Number for COLUMN=CONSTANT terms */
int nChng; /* Number of times a constant is propagated */
int bHasAffBlob; /* At least one column in apExpr[] as affinity BLOB */
u32 mExcludeOn; /* Which ON expressions to exclude from considertion.
** Either EP_OuterON or EP_InnerON|EP_OuterON */
Expr **apExpr; /* [i*2] is COLUMN and [i*2+1] is VALUE */
};
/*
** Add a new entry to the pConst object. Except, do not add duplicate
** pColumn entires. Also, do not add if doing so would not be appropriate.
**
** The caller guarantees the pColumn is a column and pValue is a constant.
** This routine has to do some additional checks before completing the
** insert.
*/
static void constInsert(
WhereConst *pConst, /* The WhereConst into which we are inserting */
Expr *pColumn, /* The COLUMN part of the constraint */
Expr *pValue, /* The VALUE part of the constraint */
Expr *pExpr /* Overall expression: COLUMN=VALUE or VALUE=COLUMN */
){
int i;
assert( pColumn->op==TK_COLUMN );
assert( sqlite3ExprIsConstant(pValue) );
if( ExprHasProperty(pColumn, EP_FixedCol) ) return;
if( sqlite3ExprAffinity(pValue)!=0 ) return;
if( !sqlite3IsBinary(sqlite3ExprCompareCollSeq(pConst->pParse,pExpr)) ){
return;
}
/* 2018-10-25 ticket [cf5ed20f]
** Make sure the same pColumn is not inserted more than once */
for(i=0; i<pConst->nConst; i++){
const Expr *pE2 = pConst->apExpr[i*2];
assert( pE2->op==TK_COLUMN );
if( pE2->iTable==pColumn->iTable
&& pE2->iColumn==pColumn->iColumn
){
return; /* Already present. Return without doing anything. */
}
}
if( sqlite3ExprAffinity(pColumn)==SQLITE_AFF_BLOB ){
pConst->bHasAffBlob = 1;
}
pConst->nConst++;
pConst->apExpr = sqlite3DbReallocOrFree(pConst->pParse->db, pConst->apExpr,
pConst->nConst*2*sizeof(Expr*));
if( pConst->apExpr==0 ){
pConst->nConst = 0;
}else{
pConst->apExpr[pConst->nConst*2-2] = pColumn;
pConst->apExpr[pConst->nConst*2-1] = pValue;
}
}
/*
** Find all terms of COLUMN=VALUE or VALUE=COLUMN in pExpr where VALUE
** is a constant expression and where the term must be true because it
** is part of the AND-connected terms of the expression. For each term
** found, add it to the pConst structure.
*/
static void findConstInWhere(WhereConst *pConst, Expr *pExpr){
Expr *pRight, *pLeft;
if( NEVER(pExpr==0) ) return;
if( ExprHasProperty(pExpr, pConst->mExcludeOn) ){
testcase( ExprHasProperty(pExpr, EP_OuterON) );
testcase( ExprHasProperty(pExpr, EP_InnerON) );
return;
}
if( pExpr->op==TK_AND ){
findConstInWhere(pConst, pExpr->pRight);
findConstInWhere(pConst, pExpr->pLeft);
return;
}
if( pExpr->op!=TK_EQ ) return;
pRight = pExpr->pRight;
pLeft = pExpr->pLeft;
assert( pRight!=0 );
assert( pLeft!=0 );
if( pRight->op==TK_COLUMN && sqlite3ExprIsConstant(pLeft) ){
constInsert(pConst,pRight,pLeft,pExpr);
}
if( pLeft->op==TK_COLUMN && sqlite3ExprIsConstant(pRight) ){
constInsert(pConst,pLeft,pRight,pExpr);
}
}
/*
** This is a helper function for Walker callback propagateConstantExprRewrite().
**
** Argument pExpr is a candidate expression to be replaced by a value. If
** pExpr is equivalent to one of the columns named in pWalker->u.pConst,
** then overwrite it with the corresponding value. Except, do not do so
** if argument bIgnoreAffBlob is non-zero and the affinity of pExpr
** is SQLITE_AFF_BLOB.
*/
static int propagateConstantExprRewriteOne(
WhereConst *pConst,
Expr *pExpr,
int bIgnoreAffBlob
){
int i;
if( pConst->pOomFault[0] ) return WRC_Prune;
if( pExpr->op!=TK_COLUMN ) return WRC_Continue;
if( ExprHasProperty(pExpr, EP_FixedCol|pConst->mExcludeOn) ){
testcase( ExprHasProperty(pExpr, EP_FixedCol) );
testcase( ExprHasProperty(pExpr, EP_OuterON) );
testcase( ExprHasProperty(pExpr, EP_InnerON) );
return WRC_Continue;
}
for(i=0; i<pConst->nConst; i++){
Expr *pColumn = pConst->apExpr[i*2];
if( pColumn==pExpr ) continue;
if( pColumn->iTable!=pExpr->iTable ) continue;
if( pColumn->iColumn!=pExpr->iColumn ) continue;
if( bIgnoreAffBlob && sqlite3ExprAffinity(pColumn)==SQLITE_AFF_BLOB ){
break;
}
/* A match is found. Add the EP_FixedCol property */
pConst->nChng++;
ExprClearProperty(pExpr, EP_Leaf);
ExprSetProperty(pExpr, EP_FixedCol);
assert( pExpr->pLeft==0 );
pExpr->pLeft = sqlite3ExprDup(pConst->pParse->db, pConst->apExpr[i*2+1], 0);
if( pConst->pParse->db->mallocFailed ) return WRC_Prune;
break;
}
return WRC_Prune;
}
/*
** This is a Walker expression callback. pExpr is a node from the WHERE
** clause of a SELECT statement. This function examines pExpr to see if
** any substitutions based on the contents of pWalker->u.pConst should
** be made to pExpr or its immediate children.
**
** A substitution is made if:
**
** + pExpr is a column with an affinity other than BLOB that matches
** one of the columns in pWalker->u.pConst, or
**
** + pExpr is a binary comparison operator (=, <=, >=, <, >) that
** uses an affinity other than TEXT and one of its immediate
** children is a column that matches one of the columns in
** pWalker->u.pConst.
*/
static int propagateConstantExprRewrite(Walker *pWalker, Expr *pExpr){
WhereConst *pConst = pWalker->u.pConst;
assert( TK_GT==TK_EQ+1 );
assert( TK_LE==TK_EQ+2 );
assert( TK_LT==TK_EQ+3 );
assert( TK_GE==TK_EQ+4 );
if( pConst->bHasAffBlob ){
if( (pExpr->op>=TK_EQ && pExpr->op<=TK_GE)
|| pExpr->op==TK_IS
){
propagateConstantExprRewriteOne(pConst, pExpr->pLeft, 0);
if( pConst->pOomFault[0] ) return WRC_Prune;
if( sqlite3ExprAffinity(pExpr->pLeft)!=SQLITE_AFF_TEXT ){
propagateConstantExprRewriteOne(pConst, pExpr->pRight, 0);
}
}
}
return propagateConstantExprRewriteOne(pConst, pExpr, pConst->bHasAffBlob);
}
/*
** The WHERE-clause constant propagation optimization.
**
** If the WHERE clause contains terms of the form COLUMN=CONSTANT or
** CONSTANT=COLUMN that are top-level AND-connected terms that are not
** part of a ON clause from a LEFT JOIN, then throughout the query
** replace all other occurrences of COLUMN with CONSTANT.
**
** For example, the query:
**
** SELECT * FROM t1, t2, t3 WHERE t1.a=39 AND t2.b=t1.a AND t3.c=t2.b
**
** Is transformed into
**
** SELECT * FROM t1, t2, t3 WHERE t1.a=39 AND t2.b=39 AND t3.c=39
**
** Return true if any transformations where made and false if not.
**
** Implementation note: Constant propagation is tricky due to affinity
** and collating sequence interactions. Consider this example:
**
** CREATE TABLE t1(a INT,b TEXT);
** INSERT INTO t1 VALUES(123,'0123');
** SELECT * FROM t1 WHERE a=123 AND b=a;
** SELECT * FROM t1 WHERE a=123 AND b=123;
**
** The two SELECT statements above should return different answers. b=a
** is alway true because the comparison uses numeric affinity, but b=123
** is false because it uses text affinity and '0123' is not the same as '123'.
** To work around this, the expression tree is not actually changed from
** "b=a" to "b=123" but rather the "a" in "b=a" is tagged with EP_FixedCol
** and the "123" value is hung off of the pLeft pointer. Code generator
** routines know to generate the constant "123" instead of looking up the
** column value. Also, to avoid collation problems, this optimization is
** only attempted if the "a=123" term uses the default BINARY collation.
**
** 2021-05-25 forum post 6a06202608: Another troublesome case is...
**
** CREATE TABLE t1(x);
** INSERT INTO t1 VALUES(10.0);
** SELECT 1 FROM t1 WHERE x=10 AND x LIKE 10;
**
** The query should return no rows, because the t1.x value is '10.0' not '10'
** and '10.0' is not LIKE '10'. But if we are not careful, the first WHERE
** term "x=10" will cause the second WHERE term to become "10 LIKE 10",
** resulting in a false positive. To avoid this, constant propagation for
** columns with BLOB affinity is only allowed if the constant is used with
** operators ==, <=, <, >=, >, or IS in a way that will cause the correct
** type conversions to occur. See logic associated with the bHasAffBlob flag
** for details.
*/
static int propagateConstants(
Parse *pParse, /* The parsing context */
Select *p /* The query in which to propagate constants */
){
WhereConst x;
Walker w;
int nChng = 0;
x.pParse = pParse;
x.pOomFault = &pParse->db->mallocFailed;
do{
x.nConst = 0;
x.nChng = 0;
x.apExpr = 0;
x.bHasAffBlob = 0;
if( ALWAYS(p->pSrc!=0)
&& p->pSrc->nSrc>0
&& (p->pSrc->a[0].fg.jointype & JT_LTORJ)!=0
){
/* Do not propagate constants on any ON clause if there is a
** RIGHT JOIN anywhere in the query */
x.mExcludeOn = EP_InnerON | EP_OuterON;
}else{
/* Do not propagate constants through the ON clause of a LEFT JOIN */
x.mExcludeOn = EP_OuterON;
}
findConstInWhere(&x, p->pWhere);
if( x.nConst ){
memset(&w, 0, sizeof(w));
w.pParse = pParse;
w.xExprCallback = propagateConstantExprRewrite;
w.xSelectCallback = sqlite3SelectWalkNoop;
w.xSelectCallback2 = 0;
w.walkerDepth = 0;
w.u.pConst = &x;
sqlite3WalkExpr(&w, p->pWhere);
sqlite3DbFree(x.pParse->db, x.apExpr);
nChng += x.nChng;
}
}while( x.nChng );
return nChng;
}
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
# if !defined(SQLITE_OMIT_WINDOWFUNC)
/*
** This function is called to determine whether or not it is safe to
** push WHERE clause expression pExpr down to FROM clause sub-query
** pSubq, which contains at least one window function. Return 1
** if it is safe and the expression should be pushed down, or 0
** otherwise.
**
** It is only safe to push the expression down if it consists only
** of constants and copies of expressions that appear in the PARTITION
** BY clause of all window function used by the sub-query. It is safe
** to filter out entire partitions, but not rows within partitions, as
** this may change the results of the window functions.
**
** At the time this function is called it is guaranteed that
**
** * the sub-query uses only one distinct window frame, and
** * that the window frame has a PARTITION BY clase.
*/
static int pushDownWindowCheck(Parse *pParse, Select *pSubq, Expr *pExpr){
assert( pSubq->pWin->pPartition );
assert( (pSubq->selFlags & SF_MultiPart)==0 );
assert( pSubq->pPrior==0 );
return sqlite3ExprIsConstantOrGroupBy(pParse, pExpr, pSubq->pWin->pPartition);
}
# endif /* SQLITE_OMIT_WINDOWFUNC */
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
/*
** Make copies of relevant WHERE clause terms of the outer query into
** the WHERE clause of subquery. Example:
**
** SELECT * FROM (SELECT a AS x, c-d AS y FROM t1) WHERE x=5 AND y=10;
**
** Transformed into:
**
** SELECT * FROM (SELECT a AS x, c-d AS y FROM t1 WHERE a=5 AND c-d=10)
** WHERE x=5 AND y=10;
**
** The hope is that the terms added to the inner query will make it more
** efficient.
**
** Do not attempt this optimization if:
**
** (1) (** This restriction was removed on 2017-09-29. We used to
** disallow this optimization for aggregate subqueries, but now
** it is allowed by putting the extra terms on the HAVING clause.
** The added HAVING clause is pointless if the subquery lacks
** a GROUP BY clause. But such a HAVING clause is also harmless
** so there does not appear to be any reason to add extra logic
** to suppress it. **)
**
** (2) The inner query is the recursive part of a common table expression.
**
** (3) The inner query has a LIMIT clause (since the changes to the WHERE
** clause would change the meaning of the LIMIT).
**
** (4) The inner query is the right operand of a LEFT JOIN and the
** expression to be pushed down does not come from the ON clause
** on that LEFT JOIN.
**
** (5) The WHERE clause expression originates in the ON or USING clause
** of a LEFT JOIN where iCursor is not the right-hand table of that
** left join. An example:
**
** SELECT *
** FROM (SELECT 1 AS a1 UNION ALL SELECT 2) AS aa
** JOIN (SELECT 1 AS b2 UNION ALL SELECT 2) AS bb ON (a1=b2)
** LEFT JOIN (SELECT 8 AS c3 UNION ALL SELECT 9) AS cc ON (b2=2);
**
** The correct answer is three rows: (1,1,NULL),(2,2,8),(2,2,9).
** But if the (b2=2) term were to be pushed down into the bb subquery,
** then the (1,1,NULL) row would be suppressed.
**
** (6) Window functions make things tricky as changes to the WHERE clause
** of the inner query could change the window over which window
** functions are calculated. Therefore, do not attempt the optimization
** if:
**
** (6a) The inner query uses multiple incompatible window partitions.
**
** (6b) The inner query is a compound and uses window-functions.
**
** (6c) The WHERE clause does not consist entirely of constants and
** copies of expressions found in the PARTITION BY clause of
** all window-functions used by the sub-query. It is safe to
** filter out entire partitions, as this does not change the
** window over which any window-function is calculated.
**
** (7) The inner query is a Common Table Expression (CTE) that should
** be materialized. (This restriction is implemented in the calling
** routine.)
**
** (8) If the subquery is a compound that uses UNION, INTERSECT,
** or EXCEPT, then all of the result set columns for all arms of
** the compound must use the BINARY collating sequence.
**
** (9) If the subquery is a compound, then all arms of the compound must
** have the same affinity. (This is the same as restriction (17h)
** for query flattening.)
**
**
** Return 0 if no changes are made and non-zero if one or more WHERE clause
** terms are duplicated into the subquery.
*/
static int pushDownWhereTerms(
Parse *pParse, /* Parse context (for malloc() and error reporting) */
Select *pSubq, /* The subquery whose WHERE clause is to be augmented */
Expr *pWhere, /* The WHERE clause of the outer query */
SrcItem *pSrc /* The subquery term of the outer FROM clause */
){
Expr *pNew;
int nChng = 0;
if( pWhere==0 ) return 0;
if( pSubq->selFlags & (SF_Recursive|SF_MultiPart) ) return 0;
if( pSrc->fg.jointype & (JT_LTORJ|JT_RIGHT) ) return 0;
if( pSubq->pPrior ){
Select *pSel;
int notUnionAll = 0;
for(pSel=pSubq; pSel; pSel=pSel->pPrior){
u8 op = pSel->op;
assert( op==TK_ALL || op==TK_SELECT
|| op==TK_UNION || op==TK_INTERSECT || op==TK_EXCEPT );
if( op!=TK_ALL && op!=TK_SELECT ){
notUnionAll = 1;
}
#ifndef SQLITE_OMIT_WINDOWFUNC
if( pSel->pWin ) return 0; /* restriction (6b) */
#endif
}
if( compoundHasDifferentAffinities(pSubq) ){
return 0; /* restriction (9) */
}
if( notUnionAll ){
/* If any of the compound arms are connected using UNION, INTERSECT,
** or EXCEPT, then we must ensure that none of the columns use a
** non-BINARY collating sequence. */
for(pSel=pSubq; pSel; pSel=pSel->pPrior){
int ii;
const ExprList *pList = pSel->pEList;
assert( pList!=0 );
for(ii=0; ii<pList->nExpr; ii++){
CollSeq *pColl = sqlite3ExprCollSeq(pParse, pList->a[ii].pExpr);
if( !sqlite3IsBinary(pColl) ){
return 0; /* Restriction (8) */
}
}
}
}
}else{
#ifndef SQLITE_OMIT_WINDOWFUNC
if( pSubq->pWin && pSubq->pWin->pPartition==0 ) return 0;
#endif
}
#ifdef SQLITE_DEBUG
/* Only the first term of a compound can have a WITH clause. But make
** sure no other terms are marked SF_Recursive in case something changes
** in the future.
*/
{
Select *pX;
for(pX=pSubq; pX; pX=pX->pPrior){
assert( (pX->selFlags & (SF_Recursive))==0 );
}
}
#endif
if( pSubq->pLimit!=0 ){
return 0; /* restriction (3) */
}
while( pWhere->op==TK_AND ){
nChng += pushDownWhereTerms(pParse, pSubq, pWhere->pRight, pSrc);
pWhere = pWhere->pLeft;
}
#if 0 /* Legacy code. Checks now done by sqlite3ExprIsTableConstraint() */
if( isLeftJoin
&& (ExprHasProperty(pWhere,EP_OuterON)==0
|| pWhere->w.iJoin!=iCursor)
){
return 0; /* restriction (4) */
}
if( ExprHasProperty(pWhere,EP_OuterON)
&& pWhere->w.iJoin!=iCursor
){
return 0; /* restriction (5) */
}
#endif
if( sqlite3ExprIsTableConstraint(pWhere, pSrc) ){
nChng++;
pSubq->selFlags |= SF_PushDown;
while( pSubq ){
SubstContext x;
pNew = sqlite3ExprDup(pParse->db, pWhere, 0);
unsetJoinExpr(pNew, -1, 1);
x.pParse = pParse;
x.iTable = pSrc->iCursor;
x.iNewTable = pSrc->iCursor;
x.isOuterJoin = 0;
x.pEList = pSubq->pEList;
x.pCList = findLeftmostExprlist(pSubq);
pNew = substExpr(&x, pNew);
#ifndef SQLITE_OMIT_WINDOWFUNC
if( pSubq->pWin && 0==pushDownWindowCheck(pParse, pSubq, pNew) ){
/* Restriction 6c has prevented push-down in this case */
sqlite3ExprDelete(pParse->db, pNew);
nChng--;
break;
}
#endif
if( pSubq->selFlags & SF_Aggregate ){
pSubq->pHaving = sqlite3ExprAnd(pParse, pSubq->pHaving, pNew);
}else{
pSubq->pWhere = sqlite3ExprAnd(pParse, pSubq->pWhere, pNew);
}
pSubq = pSubq->pPrior;
}
}
return nChng;
}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
/*
** The pFunc is the only aggregate function in the query. Check to see
** if the query is a candidate for the min/max optimization.
**
** If the query is a candidate for the min/max optimization, then set
** *ppMinMax to be an ORDER BY clause to be used for the optimization
** and return either WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX depending on
** whether pFunc is a min() or max() function.
**
** If the query is not a candidate for the min/max optimization, return
** WHERE_ORDERBY_NORMAL (which must be zero).
**
** This routine must be called after aggregate functions have been
** located but before their arguments have been subjected to aggregate
** analysis.
*/
static u8 minMaxQuery(sqlite3 *db, Expr *pFunc, ExprList **ppMinMax){
int eRet = WHERE_ORDERBY_NORMAL; /* Return value */
ExprList *pEList; /* Arguments to agg function */
const char *zFunc; /* Name of aggregate function pFunc */
ExprList *pOrderBy;
u8 sortFlags = 0;
assert( *ppMinMax==0 );
assert( pFunc->op==TK_AGG_FUNCTION );
assert( !IsWindowFunc(pFunc) );
assert( ExprUseXList(pFunc) );
pEList = pFunc->x.pList;
if( pEList==0
|| pEList->nExpr!=1
|| ExprHasProperty(pFunc, EP_WinFunc)
|| OptimizationDisabled(db, SQLITE_MinMaxOpt)
){
return eRet;
}
assert( !ExprHasProperty(pFunc, EP_IntValue) );
zFunc = pFunc->u.zToken;
if( sqlite3StrICmp(zFunc, "min")==0 ){
eRet = WHERE_ORDERBY_MIN;
if( sqlite3ExprCanBeNull(pEList->a[0].pExpr) ){
sortFlags = KEYINFO_ORDER_BIGNULL;
}
}else if( sqlite3StrICmp(zFunc, "max")==0 ){
eRet = WHERE_ORDERBY_MAX;
sortFlags = KEYINFO_ORDER_DESC;
}else{
return eRet;
}
*ppMinMax = pOrderBy = sqlite3ExprListDup(db, pEList, 0);
assert( pOrderBy!=0 || db->mallocFailed );
if( pOrderBy ) pOrderBy->a[0].fg.sortFlags = sortFlags;
return eRet;
}
/*
** The select statement passed as the first argument is an aggregate query.
** The second argument is the associated aggregate-info object. This
** function tests if the SELECT is of the form:
**
** SELECT count(*) FROM <tbl>
**
** where table is a database table, not a sub-select or view. If the query
** does match this pattern, then a pointer to the Table object representing
** <tbl> is returned. Otherwise, NULL is returned.
**
** This routine checks to see if it is safe to use the count optimization.
** A correct answer is still obtained (though perhaps more slowly) if
** this routine returns NULL when it could have returned a table pointer.
** But returning the pointer when NULL should have been returned can
** result in incorrect answers and/or crashes. So, when in doubt, return NULL.
*/
static Table *isSimpleCount(Select *p, AggInfo *pAggInfo){
Table *pTab;
Expr *pExpr;
assert( !p->pGroupBy );
if( p->pWhere
|| p->pEList->nExpr!=1
|| p->pSrc->nSrc!=1
|| p->pSrc->a[0].pSelect
|| pAggInfo->nFunc!=1
|| p->pHaving
){
return 0;
}
pTab = p->pSrc->a[0].pTab;
assert( pTab!=0 );
assert( !IsView(pTab) );
if( !IsOrdinaryTable(pTab) ) return 0;
pExpr = p->pEList->a[0].pExpr;
assert( pExpr!=0 );
if( pExpr->op!=TK_AGG_FUNCTION ) return 0;
if( pExpr->pAggInfo!=pAggInfo ) return 0;
if( (pAggInfo->aFunc[0].pFunc->funcFlags&SQLITE_FUNC_COUNT)==0 ) return 0;
assert( pAggInfo->aFunc[0].pFExpr==pExpr );
testcase( ExprHasProperty(pExpr, EP_Distinct) );
testcase( ExprHasProperty(pExpr, EP_WinFunc) );
if( ExprHasProperty(pExpr, EP_Distinct|EP_WinFunc) ) return 0;
return pTab;
}
/*
** If the source-list item passed as an argument was augmented with an
** INDEXED BY clause, then try to locate the specified index. If there
** was such a clause and the named index cannot be found, return
** SQLITE_ERROR and leave an error in pParse. Otherwise, populate
** pFrom->pIndex and return SQLITE_OK.
*/
int sqlite3IndexedByLookup(Parse *pParse, SrcItem *pFrom){
Table *pTab = pFrom->pTab;
char *zIndexedBy = pFrom->u1.zIndexedBy;
Index *pIdx;
assert( pTab!=0 );
assert( pFrom->fg.isIndexedBy!=0 );
for(pIdx=pTab->pIndex;
pIdx && sqlite3StrICmp(pIdx->zName, zIndexedBy);
pIdx=pIdx->pNext
);
if( !pIdx ){
sqlite3ErrorMsg(pParse, "no such index: %s", zIndexedBy, 0);
pParse->checkSchema = 1;
return SQLITE_ERROR;
}
assert( pFrom->fg.isCte==0 );
pFrom->u2.pIBIndex = pIdx;
return SQLITE_OK;
}
/*
** Detect compound SELECT statements that use an ORDER BY clause with
** an alternative collating sequence.
**
** SELECT ... FROM t1 EXCEPT SELECT ... FROM t2 ORDER BY .. COLLATE ...
**
** These are rewritten as a subquery:
**
** SELECT * FROM (SELECT ... FROM t1 EXCEPT SELECT ... FROM t2)
** ORDER BY ... COLLATE ...
**
** This transformation is necessary because the multiSelectOrderBy() routine
** above that generates the code for a compound SELECT with an ORDER BY clause
** uses a merge algorithm that requires the same collating sequence on the
** result columns as on the ORDER BY clause. See ticket
** http://www.sqlite.org/src/info/6709574d2a
**
** This transformation is only needed for EXCEPT, INTERSECT, and UNION.
** The UNION ALL operator works fine with multiSelectOrderBy() even when
** there are COLLATE terms in the ORDER BY.
*/
static int convertCompoundSelectToSubquery(Walker *pWalker, Select *p){
int i;
Select *pNew;
Select *pX;
sqlite3 *db;
struct ExprList_item *a;
SrcList *pNewSrc;
Parse *pParse;
Token dummy;
if( p->pPrior==0 ) return WRC_Continue;
if( p->pOrderBy==0 ) return WRC_Continue;
for(pX=p; pX && (pX->op==TK_ALL || pX->op==TK_SELECT); pX=pX->pPrior){}
if( pX==0 ) return WRC_Continue;
a = p->pOrderBy->a;
#ifndef SQLITE_OMIT_WINDOWFUNC
/* If iOrderByCol is already non-zero, then it has already been matched
** to a result column of the SELECT statement. This occurs when the
** SELECT is rewritten for window-functions processing and then passed
** to sqlite3SelectPrep() and similar a second time. The rewriting done
** by this function is not required in this case. */
if( a[0].u.x.iOrderByCol ) return WRC_Continue;
#endif
for(i=p->pOrderBy->nExpr-1; i>=0; i--){
if( a[i].pExpr->flags & EP_Collate ) break;
}
if( i<0 ) return WRC_Continue;
/* If we reach this point, that means the transformation is required. */
pParse = pWalker->pParse;
db = pParse->db;
pNew = sqlite3DbMallocZero(db, sizeof(*pNew) );
if( pNew==0 ) return WRC_Abort;
memset(&dummy, 0, sizeof(dummy));
pNewSrc = sqlite3SrcListAppendFromTerm(pParse,0,0,0,&dummy,pNew,0);
if( pNewSrc==0 ) return WRC_Abort;
*pNew = *p;
p->pSrc = pNewSrc;
p->pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db, TK_ASTERISK, 0));
p->op = TK_SELECT;
p->pWhere = 0;
pNew->pGroupBy = 0;
pNew->pHaving = 0;
pNew->pOrderBy = 0;
p->pPrior = 0;
p->pNext = 0;
p->pWith = 0;
#ifndef SQLITE_OMIT_WINDOWFUNC
p->pWinDefn = 0;
#endif
p->selFlags &= ~SF_Compound;
assert( (p->selFlags & SF_Converted)==0 );
p->selFlags |= SF_Converted;
assert( pNew->pPrior!=0 );
pNew->pPrior->pNext = pNew;
pNew->pLimit = 0;
return WRC_Continue;
}
/*
** Check to see if the FROM clause term pFrom has table-valued function
** arguments. If it does, leave an error message in pParse and return
** non-zero, since pFrom is not allowed to be a table-valued function.
*/
static int cannotBeFunction(Parse *pParse, SrcItem *pFrom){
if( pFrom->fg.isTabFunc ){
sqlite3ErrorMsg(pParse, "'%s' is not a function", pFrom->zName);
return 1;
}
return 0;
}
#ifndef SQLITE_OMIT_CTE
/*
** Argument pWith (which may be NULL) points to a linked list of nested
** WITH contexts, from inner to outermost. If the table identified by
** FROM clause element pItem is really a common-table-expression (CTE)
** then return a pointer to the CTE definition for that table. Otherwise
** return NULL.
**
** If a non-NULL value is returned, set *ppContext to point to the With
** object that the returned CTE belongs to.
*/
static struct Cte *searchWith(
With *pWith, /* Current innermost WITH clause */
SrcItem *pItem, /* FROM clause element to resolve */
With **ppContext /* OUT: WITH clause return value belongs to */
){
const char *zName = pItem->zName;
With *p;
assert( pItem->zDatabase==0 );
assert( zName!=0 );
for(p=pWith; p; p=p->pOuter){
int i;
for(i=0; i<p->nCte; i++){
if( sqlite3StrICmp(zName, p->a[i].zName)==0 ){
*ppContext = p;
return &p->a[i];
}
}
if( p->bView ) break;
}
return 0;
}
/* The code generator maintains a stack of active WITH clauses
** with the inner-most WITH clause being at the top of the stack.
**
** This routine pushes the WITH clause passed as the second argument
** onto the top of the stack. If argument bFree is true, then this
** WITH clause will never be popped from the stack but should instead
** be freed along with the Parse object. In other cases, when
** bFree==0, the With object will be freed along with the SELECT
** statement with which it is associated.
**
** This routine returns a copy of pWith. Or, if bFree is true and
** the pWith object is destroyed immediately due to an OOM condition,
** then this routine return NULL.
**
** If bFree is true, do not continue to use the pWith pointer after
** calling this routine, Instead, use only the return value.
*/
With *sqlite3WithPush(Parse *pParse, With *pWith, u8 bFree){
if( pWith ){
if( bFree ){
pWith = (With*)sqlite3ParserAddCleanup(pParse,
(void(*)(sqlite3*,void*))sqlite3WithDelete,
pWith);
if( pWith==0 ) return 0;
}
if( pParse->nErr==0 ){
assert( pParse->pWith!=pWith );
pWith->pOuter = pParse->pWith;
pParse->pWith = pWith;
}
}
return pWith;
}
/*
** This function checks if argument pFrom refers to a CTE declared by
** a WITH clause on the stack currently maintained by the parser (on the
** pParse->pWith linked list). And if currently processing a CTE
** CTE expression, through routine checks to see if the reference is
** a recursive reference to the CTE.
**
** If pFrom matches a CTE according to either of these two above, pFrom->pTab
** and other fields are populated accordingly.
**
** Return 0 if no match is found.
** Return 1 if a match is found.
** Return 2 if an error condition is detected.
*/
static int resolveFromTermToCte(
Parse *pParse, /* The parsing context */
Walker *pWalker, /* Current tree walker */
SrcItem *pFrom /* The FROM clause term to check */
){
Cte *pCte; /* Matched CTE (or NULL if no match) */
With *pWith; /* The matching WITH */
assert( pFrom->pTab==0 );
if( pParse->pWith==0 ){
/* There are no WITH clauses in the stack. No match is possible */
return 0;
}
if( pParse->nErr ){
/* Prior errors might have left pParse->pWith in a goofy state, so
** go no further. */
return 0;
}
if( pFrom->zDatabase!=0 ){
/* The FROM term contains a schema qualifier (ex: main.t1) and so
** it cannot possibly be a CTE reference. */
return 0;
}
if( pFrom->fg.notCte ){
/* The FROM term is specifically excluded from matching a CTE.
** (1) It is part of a trigger that used to have zDatabase but had
** zDatabase removed by sqlite3FixTriggerStep().
** (2) This is the first term in the FROM clause of an UPDATE.
*/
return 0;
}
pCte = searchWith(pParse->pWith, pFrom, &pWith);
if( pCte ){
sqlite3 *db = pParse->db;
Table *pTab;
ExprList *pEList;
Select *pSel;
Select *pLeft; /* Left-most SELECT statement */
Select *pRecTerm; /* Left-most recursive term */
int bMayRecursive; /* True if compound joined by UNION [ALL] */
With *pSavedWith; /* Initial value of pParse->pWith */
int iRecTab = -1; /* Cursor for recursive table */
CteUse *pCteUse;
/* If pCte->zCteErr is non-NULL at this point, then this is an illegal
** recursive reference to CTE pCte. Leave an error in pParse and return
** early. If pCte->zCteErr is NULL, then this is not a recursive reference.
** In this case, proceed. */
if( pCte->zCteErr ){
sqlite3ErrorMsg(pParse, pCte->zCteErr, pCte->zName);
return 2;
}
if( cannotBeFunction(pParse, pFrom) ) return 2;
assert( pFrom->pTab==0 );
pTab = sqlite3DbMallocZero(db, sizeof(Table));
if( pTab==0 ) return 2;
pCteUse = pCte->pUse;
if( pCteUse==0 ){
pCte->pUse = pCteUse = sqlite3DbMallocZero(db, sizeof(pCteUse[0]));
if( pCteUse==0
|| sqlite3ParserAddCleanup(pParse,sqlite3DbFree,pCteUse)==0
){
sqlite3DbFree(db, pTab);
return 2;
}
pCteUse->eM10d = pCte->eM10d;
}
pFrom->pTab = pTab;
pTab->nTabRef = 1;
pTab->zName = sqlite3DbStrDup(db, pCte->zName);
pTab->iPKey = -1;
pTab->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) );
pTab->tabFlags |= TF_Ephemeral | TF_NoVisibleRowid;
pFrom->pSelect = sqlite3SelectDup(db, pCte->pSelect, 0);
if( db->mallocFailed ) return 2;
pFrom->pSelect->selFlags |= SF_CopyCte;
assert( pFrom->pSelect );
if( pFrom->fg.isIndexedBy ){
sqlite3ErrorMsg(pParse, "no such index: \"%s\"", pFrom->u1.zIndexedBy);
return 2;
}
pFrom->fg.isCte = 1;
pFrom->u2.pCteUse = pCteUse;
pCteUse->nUse++;
if( pCteUse->nUse>=2 && pCteUse->eM10d==M10d_Any ){
pCteUse->eM10d = M10d_Yes;
}
/* Check if this is a recursive CTE. */
pRecTerm = pSel = pFrom->pSelect;
bMayRecursive = ( pSel->op==TK_ALL || pSel->op==TK_UNION );
while( bMayRecursive && pRecTerm->op==pSel->op ){
int i;
SrcList *pSrc = pRecTerm->pSrc;
assert( pRecTerm->pPrior!=0 );
for(i=0; i<pSrc->nSrc; i++){
SrcItem *pItem = &pSrc->a[i];
if( pItem->zDatabase==0
&& pItem->zName!=0
&& 0==sqlite3StrICmp(pItem->zName, pCte->zName)
){
pItem->pTab = pTab;
pTab->nTabRef++;
pItem->fg.isRecursive = 1;
if( pRecTerm->selFlags & SF_Recursive ){
sqlite3ErrorMsg(pParse,
"multiple references to recursive table: %s", pCte->zName
);
return 2;
}
pRecTerm->selFlags |= SF_Recursive;
if( iRecTab<0 ) iRecTab = pParse->nTab++;
pItem->iCursor = iRecTab;
}
}
if( (pRecTerm->selFlags & SF_Recursive)==0 ) break;
pRecTerm = pRecTerm->pPrior;
}
pCte->zCteErr = "circular reference: %s";
pSavedWith = pParse->pWith;
pParse->pWith = pWith;
if( pSel->selFlags & SF_Recursive ){
int rc;
assert( pRecTerm!=0 );
assert( (pRecTerm->selFlags & SF_Recursive)==0 );
assert( pRecTerm->pNext!=0 );
assert( (pRecTerm->pNext->selFlags & SF_Recursive)!=0 );
assert( pRecTerm->pWith==0 );
pRecTerm->pWith = pSel->pWith;
rc = sqlite3WalkSelect(pWalker, pRecTerm);
pRecTerm->pWith = 0;
if( rc ){
pParse->pWith = pSavedWith;
return 2;
}
}else{
if( sqlite3WalkSelect(pWalker, pSel) ){
pParse->pWith = pSavedWith;
return 2;
}
}
pParse->pWith = pWith;
for(pLeft=pSel; pLeft->pPrior; pLeft=pLeft->pPrior);
pEList = pLeft->pEList;
if( pCte->pCols ){
if( pEList && pEList->nExpr!=pCte->pCols->nExpr ){
sqlite3ErrorMsg(pParse, "table %s has %d values for %d columns",
pCte->zName, pEList->nExpr, pCte->pCols->nExpr
);
pParse->pWith = pSavedWith;
return 2;
}
pEList = pCte->pCols;
}
sqlite3ColumnsFromExprList(pParse, pEList, &pTab->nCol, &pTab->aCol);
if( bMayRecursive ){
if( pSel->selFlags & SF_Recursive ){
pCte->zCteErr = "multiple recursive references: %s";
}else{
pCte->zCteErr = "recursive reference in a subquery: %s";
}
sqlite3WalkSelect(pWalker, pSel);
}
pCte->zCteErr = 0;
pParse->pWith = pSavedWith;
return 1; /* Success */
}
return 0; /* No match */
}
#endif
#ifndef SQLITE_OMIT_CTE
/*
** If the SELECT passed as the second argument has an associated WITH
** clause, pop it from the stack stored as part of the Parse object.
**
** This function is used as the xSelectCallback2() callback by
** sqlite3SelectExpand() when walking a SELECT tree to resolve table
** names and other FROM clause elements.
*/
void sqlite3SelectPopWith(Walker *pWalker, Select *p){
Parse *pParse = pWalker->pParse;
if( OK_IF_ALWAYS_TRUE(pParse->pWith) && p->pPrior==0 ){
With *pWith = findRightmost(p)->pWith;
if( pWith!=0 ){
assert( pParse->pWith==pWith || pParse->nErr );
pParse->pWith = pWith->pOuter;
}
}
}
#endif
/*
** The SrcItem structure passed as the second argument represents a
** sub-query in the FROM clause of a SELECT statement. This function
** allocates and populates the SrcItem.pTab object. If successful,
** SQLITE_OK is returned. Otherwise, if an OOM error is encountered,
** SQLITE_NOMEM.
*/
int sqlite3ExpandSubquery(Parse *pParse, SrcItem *pFrom){
Select *pSel = pFrom->pSelect;
Table *pTab;
assert( pSel );
pFrom->pTab = pTab = sqlite3DbMallocZero(pParse->db, sizeof(Table));
if( pTab==0 ) return SQLITE_NOMEM;
pTab->nTabRef = 1;
if( pFrom->zAlias ){
pTab->zName = sqlite3DbStrDup(pParse->db, pFrom->zAlias);
}else{
pTab->zName = sqlite3MPrintf(pParse->db, "%!S", pFrom);
}
while( pSel->pPrior ){ pSel = pSel->pPrior; }
sqlite3ColumnsFromExprList(pParse, pSel->pEList,&pTab->nCol,&pTab->aCol);
pTab->iPKey = -1;
pTab->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) );
#ifndef SQLITE_ALLOW_ROWID_IN_VIEW
/* The usual case - do not allow ROWID on a subquery */
pTab->tabFlags |= TF_Ephemeral | TF_NoVisibleRowid;
#else
pTab->tabFlags |= TF_Ephemeral; /* Legacy compatibility mode */
#endif
return pParse->nErr ? SQLITE_ERROR : SQLITE_OK;
}
/*
** Check the N SrcItem objects to the right of pBase. (N might be zero!)
** If any of those SrcItem objects have a USING clause containing zName
** then return true.
**
** If N is zero, or none of the N SrcItem objects to the right of pBase
** contains a USING clause, or if none of the USING clauses contain zName,
** then return false.
*/
static int inAnyUsingClause(
const char *zName, /* Name we are looking for */
SrcItem *pBase, /* The base SrcItem. Looking at pBase[1] and following */
int N /* How many SrcItems to check */
){
while( N>0 ){
N--;
pBase++;
if( pBase->fg.isUsing==0 ) continue;
if( NEVER(pBase->u3.pUsing==0) ) continue;
if( sqlite3IdListIndex(pBase->u3.pUsing, zName)>=0 ) return 1;
}
return 0;
}
/*
** This routine is a Walker callback for "expanding" a SELECT statement.
** "Expanding" means to do the following:
**
** (1) Make sure VDBE cursor numbers have been assigned to every
** element of the FROM clause.
**
** (2) Fill in the pTabList->a[].pTab fields in the SrcList that
** defines FROM clause. When views appear in the FROM clause,
** fill pTabList->a[].pSelect with a copy of the SELECT statement
** that implements the view. A copy is made of the view's SELECT
** statement so that we can freely modify or delete that statement
** without worrying about messing up the persistent representation
** of the view.
**
** (3) Add terms to the WHERE clause to accommodate the NATURAL keyword
** on joins and the ON and USING clause of joins.
**
** (4) Scan the list of columns in the result set (pEList) looking
** for instances of the "*" operator or the TABLE.* operator.
** If found, expand each "*" to be every column in every table
** and TABLE.* to be every column in TABLE.
**
*/
static int selectExpander(Walker *pWalker, Select *p){
Parse *pParse = pWalker->pParse;
int i, j, k, rc;
SrcList *pTabList;
ExprList *pEList;
SrcItem *pFrom;
sqlite3 *db = pParse->db;
Expr *pE, *pRight, *pExpr;
u16 selFlags = p->selFlags;
u32 elistFlags = 0;
p->selFlags |= SF_Expanded;
if( db->mallocFailed ){
return WRC_Abort;
}
assert( p->pSrc!=0 );
if( (selFlags & SF_Expanded)!=0 ){
return WRC_Prune;
}
if( pWalker->eCode ){
/* Renumber selId because it has been copied from a view */
p->selId = ++pParse->nSelect;
}
pTabList = p->pSrc;
pEList = p->pEList;
if( pParse->pWith && (p->selFlags & SF_View) ){
if( p->pWith==0 ){
p->pWith = (With*)sqlite3DbMallocZero(db, sizeof(With));
if( p->pWith==0 ){
return WRC_Abort;
}
}
p->pWith->bView = 1;
}
sqlite3WithPush(pParse, p->pWith, 0);
/* Make sure cursor numbers have been assigned to all entries in
** the FROM clause of the SELECT statement.
*/
sqlite3SrcListAssignCursors(pParse, pTabList);
/* Look up every table named in the FROM clause of the select. If
** an entry of the FROM clause is a subquery instead of a table or view,
** then create a transient table structure to describe the subquery.
*/
for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
Table *pTab;
assert( pFrom->fg.isRecursive==0 || pFrom->pTab!=0 );
if( pFrom->pTab ) continue;
assert( pFrom->fg.isRecursive==0 );
if( pFrom->zName==0 ){
#ifndef SQLITE_OMIT_SUBQUERY
Select *pSel = pFrom->pSelect;
/* A sub-query in the FROM clause of a SELECT */
assert( pSel!=0 );
assert( pFrom->pTab==0 );
if( sqlite3WalkSelect(pWalker, pSel) ) return WRC_Abort;
if( sqlite3ExpandSubquery(pParse, pFrom) ) return WRC_Abort;
#endif
#ifndef SQLITE_OMIT_CTE
}else if( (rc = resolveFromTermToCte(pParse, pWalker, pFrom))!=0 ){
if( rc>1 ) return WRC_Abort;
pTab = pFrom->pTab;
assert( pTab!=0 );
#endif
}else{
/* An ordinary table or view name in the FROM clause */
assert( pFrom->pTab==0 );
pFrom->pTab = pTab = sqlite3LocateTableItem(pParse, 0, pFrom);
if( pTab==0 ) return WRC_Abort;
if( pTab->nTabRef>=0xffff ){
sqlite3ErrorMsg(pParse, "too many references to \"%s\": max 65535",
pTab->zName);
pFrom->pTab = 0;
return WRC_Abort;
}
pTab->nTabRef++;
if( !IsVirtual(pTab) && cannotBeFunction(pParse, pFrom) ){
return WRC_Abort;
}
#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_VIRTUALTABLE)
if( !IsOrdinaryTable(pTab) ){
i16 nCol;
u8 eCodeOrig = pWalker->eCode;
if( sqlite3ViewGetColumnNames(pParse, pTab) ) return WRC_Abort;
assert( pFrom->pSelect==0 );
if( IsView(pTab) ){
if( (db->flags & SQLITE_EnableView)==0
&& pTab->pSchema!=db->aDb[1].pSchema
){
sqlite3ErrorMsg(pParse, "access to view \"%s\" prohibited",
pTab->zName);
}
pFrom->pSelect = sqlite3SelectDup(db, pTab->u.view.pSelect, 0);
}
#ifndef SQLITE_OMIT_VIRTUALTABLE
else if( ALWAYS(IsVirtual(pTab))
&& pFrom->fg.fromDDL
&& ALWAYS(pTab->u.vtab.p!=0)
&& pTab->u.vtab.p->eVtabRisk > ((db->flags & SQLITE_TrustedSchema)!=0)
){
sqlite3ErrorMsg(pParse, "unsafe use of virtual table \"%s\"",
pTab->zName);
}
assert( SQLITE_VTABRISK_Normal==1 && SQLITE_VTABRISK_High==2 );
#endif
nCol = pTab->nCol;
pTab->nCol = -1;
pWalker->eCode = 1; /* Turn on Select.selId renumbering */
sqlite3WalkSelect(pWalker, pFrom->pSelect);
pWalker->eCode = eCodeOrig;
pTab->nCol = nCol;
}
#endif
}
/* Locate the index named by the INDEXED BY clause, if any. */
if( pFrom->fg.isIndexedBy && sqlite3IndexedByLookup(pParse, pFrom) ){
return WRC_Abort;
}
}
/* Process NATURAL keywords, and ON and USING clauses of joins.
*/
assert( db->mallocFailed==0 || pParse->nErr!=0 );
if( pParse->nErr || sqlite3ProcessJoin(pParse, p) ){
return WRC_Abort;
}
/* For every "*" that occurs in the column list, insert the names of
** all columns in all tables. And for every TABLE.* insert the names
** of all columns in TABLE. The parser inserted a special expression
** with the TK_ASTERISK operator for each "*" that it found in the column
** list. The following code just has to locate the TK_ASTERISK
** expressions and expand each one to the list of all columns in
** all tables.
**
** The first loop just checks to see if there are any "*" operators
** that need expanding.
*/
for(k=0; k<pEList->nExpr; k++){
pE = pEList->a[k].pExpr;
if( pE->op==TK_ASTERISK ) break;
assert( pE->op!=TK_DOT || pE->pRight!=0 );
assert( pE->op!=TK_DOT || (pE->pLeft!=0 && pE->pLeft->op==TK_ID) );
if( pE->op==TK_DOT && pE->pRight->op==TK_ASTERISK ) break;
elistFlags |= pE->flags;
}
if( k<pEList->nExpr ){
/*
** If we get here it means the result set contains one or more "*"
** operators that need to be expanded. Loop through each expression
** in the result set and expand them one by one.
*/
struct ExprList_item *a = pEList->a;
ExprList *pNew = 0;
int flags = pParse->db->flags;
int longNames = (flags & SQLITE_FullColNames)!=0
&& (flags & SQLITE_ShortColNames)==0;
for(k=0; k<pEList->nExpr; k++){
pE = a[k].pExpr;
elistFlags |= pE->flags;
pRight = pE->pRight;
assert( pE->op!=TK_DOT || pRight!=0 );
if( pE->op!=TK_ASTERISK
&& (pE->op!=TK_DOT || pRight->op!=TK_ASTERISK)
){
/* This particular expression does not need to be expanded.
*/
pNew = sqlite3ExprListAppend(pParse, pNew, a[k].pExpr);
if( pNew ){
pNew->a[pNew->nExpr-1].zEName = a[k].zEName;
pNew->a[pNew->nExpr-1].fg.eEName = a[k].fg.eEName;
a[k].zEName = 0;
}
a[k].pExpr = 0;
}else{
/* This expression is a "*" or a "TABLE.*" and needs to be
** expanded. */
int tableSeen = 0; /* Set to 1 when TABLE matches */
char *zTName = 0; /* text of name of TABLE */
if( pE->op==TK_DOT ){
assert( pE->pLeft!=0 );
assert( !ExprHasProperty(pE->pLeft, EP_IntValue) );
zTName = pE->pLeft->u.zToken;
}
for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
Table *pTab = pFrom->pTab; /* Table for this data source */
ExprList *pNestedFrom; /* Result-set of a nested FROM clause */
char *zTabName; /* AS name for this data source */
const char *zSchemaName = 0; /* Schema name for this data source */
int iDb; /* Schema index for this data src */
IdList *pUsing; /* USING clause for pFrom[1] */
if( (zTabName = pFrom->zAlias)==0 ){
zTabName = pTab->zName;
}
if( db->mallocFailed ) break;
assert( (int)pFrom->fg.isNestedFrom == IsNestedFrom(pFrom->pSelect) );
if( pFrom->fg.isNestedFrom ){
assert( pFrom->pSelect!=0 );
pNestedFrom = pFrom->pSelect->pEList;
assert( pNestedFrom!=0 );
assert( pNestedFrom->nExpr==pTab->nCol );
}else{
if( zTName && sqlite3StrICmp(zTName, zTabName)!=0 ){
continue;
}
pNestedFrom = 0;
iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
zSchemaName = iDb>=0 ? db->aDb[iDb].zDbSName : "*";
}
if( i+1<pTabList->nSrc
&& pFrom[1].fg.isUsing
&& (selFlags & SF_NestedFrom)!=0
){
int ii;
pUsing = pFrom[1].u3.pUsing;
for(ii=0; ii<pUsing->nId; ii++){
const char *zUName = pUsing->a[ii].zName;
pRight = sqlite3Expr(db, TK_ID, zUName);
pNew = sqlite3ExprListAppend(pParse, pNew, pRight);
if( pNew ){
struct ExprList_item *pX = &pNew->a[pNew->nExpr-1];
assert( pX->zEName==0 );
pX->zEName = sqlite3MPrintf(db,"..%s", zUName);
pX->fg.eEName = ENAME_TAB;
pX->fg.bUsingTerm = 1;
}
}
}else{
pUsing = 0;
}
for(j=0; j<pTab->nCol; j++){
char *zName = pTab->aCol[j].zCnName;
struct ExprList_item *pX; /* Newly added ExprList term */
assert( zName );
if( zTName
&& pNestedFrom
&& sqlite3MatchEName(&pNestedFrom->a[j], 0, zTName, 0)==0
){
continue;
}
/* If a column is marked as 'hidden', omit it from the expanded
** result-set list unless the SELECT has the SF_IncludeHidden
** bit set.
*/
if( (p->selFlags & SF_IncludeHidden)==0
&& IsHiddenColumn(&pTab->aCol[j])
){
continue;
}
if( (pTab->aCol[j].colFlags & COLFLAG_NOEXPAND)!=0
&& zTName==0
&& (selFlags & (SF_NestedFrom))==0
){
continue;
}
tableSeen = 1;
if( i>0 && zTName==0 && (selFlags & SF_NestedFrom)==0 ){
if( pFrom->fg.isUsing
&& sqlite3IdListIndex(pFrom->u3.pUsing, zName)>=0
){
/* In a join with a USING clause, omit columns in the
** using clause from the table on the right. */
continue;
}
}
pRight = sqlite3Expr(db, TK_ID, zName);
if( (pTabList->nSrc>1
&& ( (pFrom->fg.jointype & JT_LTORJ)==0
|| (selFlags & SF_NestedFrom)!=0
|| !inAnyUsingClause(zName,pFrom,pTabList->nSrc-i-1)
)
)
|| IN_RENAME_OBJECT
){
Expr *pLeft;
pLeft = sqlite3Expr(db, TK_ID, zTabName);
pExpr = sqlite3PExpr(pParse, TK_DOT, pLeft, pRight);
if( IN_RENAME_OBJECT && pE->pLeft ){
sqlite3RenameTokenRemap(pParse, pLeft, pE->pLeft);
}
if( zSchemaName ){
pLeft = sqlite3Expr(db, TK_ID, zSchemaName);
pExpr = sqlite3PExpr(pParse, TK_DOT, pLeft, pExpr);
}
}else{
pExpr = pRight;
}
pNew = sqlite3ExprListAppend(pParse, pNew, pExpr);
if( pNew==0 ){
break; /* OOM */
}
pX = &pNew->a[pNew->nExpr-1];
assert( pX->zEName==0 );
if( (selFlags & SF_NestedFrom)!=0 && !IN_RENAME_OBJECT ){
if( pNestedFrom ){
pX->zEName = sqlite3DbStrDup(db, pNestedFrom->a[j].zEName);
testcase( pX->zEName==0 );
}else{
pX->zEName = sqlite3MPrintf(db, "%s.%s.%s",
zSchemaName, zTabName, zName);
testcase( pX->zEName==0 );
}
pX->fg.eEName = ENAME_TAB;
if( (pFrom->fg.isUsing
&& sqlite3IdListIndex(pFrom->u3.pUsing, zName)>=0)
|| (pUsing && sqlite3IdListIndex(pUsing, zName)>=0)
|| (pTab->aCol[j].colFlags & COLFLAG_NOEXPAND)!=0
){
pX->fg.bNoExpand = 1;
}
}else if( longNames ){
pX->zEName = sqlite3MPrintf(db, "%s.%s", zTabName, zName);
pX->fg.eEName = ENAME_NAME;
}else{
pX->zEName = sqlite3DbStrDup(db, zName);
pX->fg.eEName = ENAME_NAME;
}
}
}
if( !tableSeen ){
if( zTName ){
sqlite3ErrorMsg(pParse, "no such table: %s", zTName);
}else{
sqlite3ErrorMsg(pParse, "no tables specified");
}
}
}
}
sqlite3ExprListDelete(db, pEList);
p->pEList = pNew;
}
if( p->pEList ){
if( p->pEList->nExpr>db->aLimit[SQLITE_LIMIT_COLUMN] ){
sqlite3ErrorMsg(pParse, "too many columns in result set");
return WRC_Abort;
}
if( (elistFlags & (EP_HasFunc|EP_Subquery))!=0 ){
p->selFlags |= SF_ComplexResult;
}
}
#if TREETRACE_ENABLED
if( sqlite3TreeTrace & 0x8 ){
TREETRACE(0x8,pParse,p,("After result-set wildcard expansion:\n"));
sqlite3TreeViewSelect(0, p, 0);
}
#endif
return WRC_Continue;
}
#if SQLITE_DEBUG
/*
** Always assert. This xSelectCallback2 implementation proves that the
** xSelectCallback2 is never invoked.
*/
void sqlite3SelectWalkAssert2(Walker *NotUsed, Select *NotUsed2){
UNUSED_PARAMETER2(NotUsed, NotUsed2);
assert( 0 );
}
#endif
/*
** This routine "expands" a SELECT statement and all of its subqueries.
** For additional information on what it means to "expand" a SELECT
** statement, see the comment on the selectExpand worker callback above.
**
** Expanding a SELECT statement is the first step in processing a
** SELECT statement. The SELECT statement must be expanded before
** name resolution is performed.
**
** If anything goes wrong, an error message is written into pParse.
** The calling function can detect the problem by looking at pParse->nErr
** and/or pParse->db->mallocFailed.
*/
static void sqlite3SelectExpand(Parse *pParse, Select *pSelect){
Walker w;
w.xExprCallback = sqlite3ExprWalkNoop;
w.pParse = pParse;
if( OK_IF_ALWAYS_TRUE(pParse->hasCompound) ){
w.xSelectCallback = convertCompoundSelectToSubquery;
w.xSelectCallback2 = 0;
sqlite3WalkSelect(&w, pSelect);
}
w.xSelectCallback = selectExpander;
w.xSelectCallback2 = sqlite3SelectPopWith;
w.eCode = 0;
sqlite3WalkSelect(&w, pSelect);
}
#ifndef SQLITE_OMIT_SUBQUERY
/*
** This is a Walker.xSelectCallback callback for the sqlite3SelectTypeInfo()
** interface.
**
** For each FROM-clause subquery, add Column.zType, Column.zColl, and
** Column.affinity information to the Table structure that represents
** the result set of that subquery.
**
** The Table structure that represents the result set was constructed
** by selectExpander() but the type and collation and affinity information
** was omitted at that point because identifiers had not yet been resolved.
** This routine is called after identifier resolution.
*/
static void selectAddSubqueryTypeInfo(Walker *pWalker, Select *p){
Parse *pParse;
int i;
SrcList *pTabList;
SrcItem *pFrom;
assert( p->selFlags & SF_Resolved );
if( p->selFlags & SF_HasTypeInfo ) return;
p->selFlags |= SF_HasTypeInfo;
pParse = pWalker->pParse;
pTabList = p->pSrc;
for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
Table *pTab = pFrom->pTab;
assert( pTab!=0 );
if( (pTab->tabFlags & TF_Ephemeral)!=0 ){
/* A sub-query in the FROM clause of a SELECT */
Select *pSel = pFrom->pSelect;
if( pSel ){
sqlite3SubqueryColumnTypes(pParse, pTab, pSel, SQLITE_AFF_NONE);
}
}
}
}
#endif
/*
** This routine adds datatype and collating sequence information to
** the Table structures of all FROM-clause subqueries in a
** SELECT statement.
**
** Use this routine after name resolution.
*/
static void sqlite3SelectAddTypeInfo(Parse *pParse, Select *pSelect){
#ifndef SQLITE_OMIT_SUBQUERY
Walker w;
w.xSelectCallback = sqlite3SelectWalkNoop;
w.xSelectCallback2 = selectAddSubqueryTypeInfo;
w.xExprCallback = sqlite3ExprWalkNoop;
w.pParse = pParse;
sqlite3WalkSelect(&w, pSelect);
#endif
}
/*
** This routine sets up a SELECT statement for processing. The
** following is accomplished:
**
** * VDBE Cursor numbers are assigned to all FROM-clause terms.
** * Ephemeral Table objects are created for all FROM-clause subqueries.
** * ON and USING clauses are shifted into WHERE statements
** * Wildcards "*" and "TABLE.*" in result sets are expanded.
** * Identifiers in expression are matched to tables.
**
** This routine acts recursively on all subqueries within the SELECT.
*/
void sqlite3SelectPrep(
Parse *pParse, /* The parser context */
Select *p, /* The SELECT statement being coded. */
NameContext *pOuterNC /* Name context for container */
){
assert( p!=0 || pParse->db->mallocFailed );
assert( pParse->db->pParse==pParse );
if( pParse->db->mallocFailed ) return;
if( p->selFlags & SF_HasTypeInfo ) return;
sqlite3SelectExpand(pParse, p);
if( pParse->nErr ) return;
sqlite3ResolveSelectNames(pParse, p, pOuterNC);
if( pParse->nErr ) return;
sqlite3SelectAddTypeInfo(pParse, p);
}
#if TREETRACE_ENABLED
/*
** Display all information about an AggInfo object
*/
static void printAggInfo(AggInfo *pAggInfo){
int ii;
for(ii=0; ii<pAggInfo->nColumn; ii++){
struct AggInfo_col *pCol = &pAggInfo->aCol[ii];
sqlite3DebugPrintf(
"agg-column[%d] pTab=%s iTable=%d iColumn=%d iMem=%d"
" iSorterColumn=%d %s\n",
ii, pCol->pTab ? pCol->pTab->zName : "NULL",
pCol->iTable, pCol->iColumn, pAggInfo->iFirstReg+ii,
pCol->iSorterColumn,
ii>=pAggInfo->nAccumulator ? "" : " Accumulator");
sqlite3TreeViewExpr(0, pAggInfo->aCol[ii].pCExpr, 0);
}
for(ii=0; ii<pAggInfo->nFunc; ii++){
sqlite3DebugPrintf("agg-func[%d]: iMem=%d\n",
ii, pAggInfo->iFirstReg+pAggInfo->nColumn+ii);
sqlite3TreeViewExpr(0, pAggInfo->aFunc[ii].pFExpr, 0);
}
}
#endif /* TREETRACE_ENABLED */
/*
** Analyze the arguments to aggregate functions. Create new pAggInfo->aCol[]
** entries for columns that are arguments to aggregate functions but which
** are not otherwise used.
**
** The aCol[] entries in AggInfo prior to nAccumulator are columns that
** are referenced outside of aggregate functions. These might be columns
** that are part of the GROUP by clause, for example. Other database engines
** would throw an error if there is a column reference that is not in the
** GROUP BY clause and that is not part of an aggregate function argument.
** But SQLite allows this.
**
** The aCol[] entries beginning with the aCol[nAccumulator] and following
** are column references that are used exclusively as arguments to
** aggregate functions. This routine is responsible for computing
** (or recomputing) those aCol[] entries.
*/
static void analyzeAggFuncArgs(
AggInfo *pAggInfo,
NameContext *pNC
){
int i;
assert( pAggInfo!=0 );
assert( pAggInfo->iFirstReg==0 );
pNC->ncFlags |= NC_InAggFunc;
for(i=0; i<pAggInfo->nFunc; i++){
Expr *pExpr = pAggInfo->aFunc[i].pFExpr;
assert( ExprUseXList(pExpr) );
sqlite3ExprAnalyzeAggList(pNC, pExpr->x.pList);
#ifndef SQLITE_OMIT_WINDOWFUNC
assert( !IsWindowFunc(pExpr) );
if( ExprHasProperty(pExpr, EP_WinFunc) ){
sqlite3ExprAnalyzeAggregates(pNC, pExpr->y.pWin->pFilter);
}
#endif
}
pNC->ncFlags &= ~NC_InAggFunc;
}
/*
** An index on expressions is being used in the inner loop of an
** aggregate query with a GROUP BY clause. This routine attempts
** to adjust the AggInfo object to take advantage of index and to
** perhaps use the index as a covering index.
**
*/
static void optimizeAggregateUseOfIndexedExpr(
Parse *pParse, /* Parsing context */
Select *pSelect, /* The SELECT statement being processed */
AggInfo *pAggInfo, /* The aggregate info */
NameContext *pNC /* Name context used to resolve agg-func args */
){
assert( pAggInfo->iFirstReg==0 );
pAggInfo->nColumn = pAggInfo->nAccumulator;
if( ALWAYS(pAggInfo->nSortingColumn>0) ){
if( pAggInfo->nColumn==0 ){
pAggInfo->nSortingColumn = 0;
}else{
pAggInfo->nSortingColumn =
pAggInfo->aCol[pAggInfo->nColumn-1].iSorterColumn+1;
}
}
analyzeAggFuncArgs(pAggInfo, pNC);
#if TREETRACE_ENABLED
if( sqlite3TreeTrace & 0x20 ){
IndexedExpr *pIEpr;
TREETRACE(0x20, pParse, pSelect,
("AggInfo (possibly) adjusted for Indexed Exprs\n"));
sqlite3TreeViewSelect(0, pSelect, 0);
for(pIEpr=pParse->pIdxEpr; pIEpr; pIEpr=pIEpr->pIENext){
printf("data-cursor=%d index={%d,%d}\n",
pIEpr->iDataCur, pIEpr->iIdxCur, pIEpr->iIdxCol);
sqlite3TreeViewExpr(0, pIEpr->pExpr, 0);
}
printAggInfo(pAggInfo);
}
#else
UNUSED_PARAMETER(pSelect);
UNUSED_PARAMETER(pParse);
#endif
}
/*
** Walker callback for aggregateConvertIndexedExprRefToColumn().
*/
static int aggregateIdxEprRefToColCallback(Walker *pWalker, Expr *pExpr){
AggInfo *pAggInfo;
struct AggInfo_col *pCol;
UNUSED_PARAMETER(pWalker);
if( pExpr->pAggInfo==0 ) return WRC_Continue;
if( pExpr->op==TK_AGG_COLUMN ) return WRC_Continue;
if( pExpr->op==TK_AGG_FUNCTION ) return WRC_Continue;
if( pExpr->op==TK_IF_NULL_ROW ) return WRC_Continue;
pAggInfo = pExpr->pAggInfo;
assert( pExpr->iAgg>=0 && pExpr->iAgg<pAggInfo->nColumn );
pCol = &pAggInfo->aCol[pExpr->iAgg];
pExpr->op = TK_AGG_COLUMN;
pExpr->iTable = pCol->iTable;
pExpr->iColumn = pCol->iColumn;
return WRC_Prune;
}
/*
** Convert every pAggInfo->aFunc[].pExpr such that any node within
** those expressions that has pAppInfo set is changed into a TK_AGG_COLUMN
** opcode.
*/
static void aggregateConvertIndexedExprRefToColumn(AggInfo *pAggInfo){
int i;
Walker w;
memset(&w, 0, sizeof(w));
w.xExprCallback = aggregateIdxEprRefToColCallback;
for(i=0; i<pAggInfo->nFunc; i++){
sqlite3WalkExpr(&w, pAggInfo->aFunc[i].pFExpr);
}
}
/*
** Allocate a block of registers so that there is one register for each
** pAggInfo->aCol[] and pAggInfo->aFunc[] entry in pAggInfo. The first
** register in this block is stored in pAggInfo->iFirstReg.
**
** This routine may only be called once for each AggInfo object. Prior
** to calling this routine:
**
** * The aCol[] and aFunc[] arrays may be modified
** * The AggInfoColumnReg() and AggInfoFuncReg() macros may not be used
**
** After clling this routine:
**
** * The aCol[] and aFunc[] arrays are fixed
** * The AggInfoColumnReg() and AggInfoFuncReg() macros may be used
**
*/
static void assignAggregateRegisters(Parse *pParse, AggInfo *pAggInfo){
assert( pAggInfo!=0 );
assert( pAggInfo->iFirstReg==0 );
pAggInfo->iFirstReg = pParse->nMem + 1;
pParse->nMem += pAggInfo->nColumn + pAggInfo->nFunc;
}
/*
** Reset the aggregate accumulator.
**
** The aggregate accumulator is a set of memory cells that hold
** intermediate results while calculating an aggregate. This
** routine generates code that stores NULLs in all of those memory
** cells.
*/
static void resetAccumulator(Parse *pParse, AggInfo *pAggInfo){
Vdbe *v = pParse->pVdbe;
int i;
struct AggInfo_func *pFunc;
int nReg = pAggInfo->nFunc + pAggInfo->nColumn;
assert( pAggInfo->iFirstReg>0 );
assert( pParse->db->pParse==pParse );
assert( pParse->db->mallocFailed==0 || pParse->nErr!=0 );
if( nReg==0 ) return;
if( pParse->nErr ) return;
sqlite3VdbeAddOp3(v, OP_Null, 0, pAggInfo->iFirstReg,
pAggInfo->iFirstReg+nReg-1);
for(pFunc=pAggInfo->aFunc, i=0; i<pAggInfo->nFunc; i++, pFunc++){
if( pFunc->iDistinct>=0 ){
Expr *pE = pFunc->pFExpr;
assert( ExprUseXList(pE) );
if( pE->x.pList==0 || pE->x.pList->nExpr!=1 ){
sqlite3ErrorMsg(pParse, "DISTINCT aggregates must have exactly one "
"argument");
pFunc->iDistinct = -1;
}else{
KeyInfo *pKeyInfo = sqlite3KeyInfoFromExprList(pParse, pE->x.pList,0,0);
pFunc->iDistAddr = sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
pFunc->iDistinct, 0, 0, (char*)pKeyInfo, P4_KEYINFO);
ExplainQueryPlan((pParse, 0, "USE TEMP B-TREE FOR %s(DISTINCT)",
pFunc->pFunc->zName));
}
}
}
}
/*
** Invoke the OP_AggFinalize opcode for every aggregate function
** in the AggInfo structure.
*/
static void finalizeAggFunctions(Parse *pParse, AggInfo *pAggInfo){
Vdbe *v = pParse->pVdbe;
int i;
struct AggInfo_func *pF;
for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
ExprList *pList;
assert( ExprUseXList(pF->pFExpr) );
pList = pF->pFExpr->x.pList;
sqlite3VdbeAddOp2(v, OP_AggFinal, AggInfoFuncReg(pAggInfo,i),
pList ? pList->nExpr : 0);
sqlite3VdbeAppendP4(v, pF->pFunc, P4_FUNCDEF);
}
}
/*
** Generate code that will update the accumulator memory cells for an
** aggregate based on the current cursor position.
**
** If regAcc is non-zero and there are no min() or max() aggregates
** in pAggInfo, then only populate the pAggInfo->nAccumulator accumulator
** registers if register regAcc contains 0. The caller will take care
** of setting and clearing regAcc.
*/
static void updateAccumulator(
Parse *pParse,
int regAcc,
AggInfo *pAggInfo,
int eDistinctType
){
Vdbe *v = pParse->pVdbe;
int i;
int regHit = 0;
int addrHitTest = 0;
struct AggInfo_func *pF;
struct AggInfo_col *pC;
assert( pAggInfo->iFirstReg>0 );
if( pParse->nErr ) return;
pAggInfo->directMode = 1;
for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
int nArg;
int addrNext = 0;
int regAgg;
ExprList *pList;
assert( ExprUseXList(pF->pFExpr) );
assert( !IsWindowFunc(pF->pFExpr) );
pList = pF->pFExpr->x.pList;
if( ExprHasProperty(pF->pFExpr, EP_WinFunc) ){
Expr *pFilter = pF->pFExpr->y.pWin->pFilter;
if( pAggInfo->nAccumulator
&& (pF->pFunc->funcFlags & SQLITE_FUNC_NEEDCOLL)
&& regAcc
){
/* If regAcc==0, there there exists some min() or max() function
** without a FILTER clause that will ensure the magnet registers
** are populated. */
if( regHit==0 ) regHit = ++pParse->nMem;
/* If this is the first row of the group (regAcc contains 0), clear the
** "magnet" register regHit so that the accumulator registers
** are populated if the FILTER clause jumps over the the
** invocation of min() or max() altogether. Or, if this is not
** the first row (regAcc contains 1), set the magnet register so that
** the accumulators are not populated unless the min()/max() is invoked
** and indicates that they should be. */
sqlite3VdbeAddOp2(v, OP_Copy, regAcc, regHit);
}
addrNext = sqlite3VdbeMakeLabel(pParse);
sqlite3ExprIfFalse(pParse, pFilter, addrNext, SQLITE_JUMPIFNULL);
}
if( pList ){
nArg = pList->nExpr;
regAgg = sqlite3GetTempRange(pParse, nArg);
sqlite3ExprCodeExprList(pParse, pList, regAgg, 0, SQLITE_ECEL_DUP);
}else{
nArg = 0;
regAgg = 0;
}
if( pF->iDistinct>=0 && pList ){
if( addrNext==0 ){
addrNext = sqlite3VdbeMakeLabel(pParse);
}
pF->iDistinct = codeDistinct(pParse, eDistinctType,
pF->iDistinct, addrNext, pList, regAgg);
}
if( pF->pFunc->funcFlags & SQLITE_FUNC_NEEDCOLL ){
CollSeq *pColl = 0;
struct ExprList_item *pItem;
int j;
assert( pList!=0 ); /* pList!=0 if pF->pFunc has NEEDCOLL */
for(j=0, pItem=pList->a; !pColl && j<nArg; j++, pItem++){
pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
}
if( !pColl ){
pColl = pParse->db->pDfltColl;
}
if( regHit==0 && pAggInfo->nAccumulator ) regHit = ++pParse->nMem;
sqlite3VdbeAddOp4(v, OP_CollSeq, regHit, 0, 0, (char *)pColl, P4_COLLSEQ);
}
sqlite3VdbeAddOp3(v, OP_AggStep, 0, regAgg, AggInfoFuncReg(pAggInfo,i));
sqlite3VdbeAppendP4(v, pF->pFunc, P4_FUNCDEF);
sqlite3VdbeChangeP5(v, (u8)nArg);
sqlite3ReleaseTempRange(pParse, regAgg, nArg);
if( addrNext ){
sqlite3VdbeResolveLabel(v, addrNext);
}
}
if( regHit==0 && pAggInfo->nAccumulator ){
regHit = regAcc;
}
if( regHit ){
addrHitTest = sqlite3VdbeAddOp1(v, OP_If, regHit); VdbeCoverage(v);
}
for(i=0, pC=pAggInfo->aCol; i<pAggInfo->nAccumulator; i++, pC++){
sqlite3ExprCode(pParse, pC->pCExpr, AggInfoColumnReg(pAggInfo,i));
}
pAggInfo->directMode = 0;
if( addrHitTest ){
sqlite3VdbeJumpHereOrPopInst(v, addrHitTest);
}
}
/*
** Add a single OP_Explain instruction to the VDBE to explain a simple
** count(*) query ("SELECT count(*) FROM pTab").
*/
#ifndef SQLITE_OMIT_EXPLAIN
static void explainSimpleCount(
Parse *pParse, /* Parse context */
Table *pTab, /* Table being queried */
Index *pIdx /* Index used to optimize scan, or NULL */
){
if( pParse->explain==2 ){
int bCover = (pIdx!=0 && (HasRowid(pTab) || !IsPrimaryKeyIndex(pIdx)));
sqlite3VdbeExplain(pParse, 0, "SCAN %s%s%s",
pTab->zName,
bCover ? " USING COVERING INDEX " : "",
bCover ? pIdx->zName : ""
);
}
}
#else
# define explainSimpleCount(a,b,c)
#endif
/*
** sqlite3WalkExpr() callback used by havingToWhere().
**
** If the node passed to the callback is a TK_AND node, return
** WRC_Continue to tell sqlite3WalkExpr() to iterate through child nodes.
**
** Otherwise, return WRC_Prune. In this case, also check if the
** sub-expression matches the criteria for being moved to the WHERE
** clause. If so, add it to the WHERE clause and replace the sub-expression
** within the HAVING expression with a constant "1".
*/
static int havingToWhereExprCb(Walker *pWalker, Expr *pExpr){
if( pExpr->op!=TK_AND ){
Select *pS = pWalker->u.pSelect;
/* This routine is called before the HAVING clause of the current
** SELECT is analyzed for aggregates. So if pExpr->pAggInfo is set
** here, it indicates that the expression is a correlated reference to a
** column from an outer aggregate query, or an aggregate function that
** belongs to an outer query. Do not move the expression to the WHERE
** clause in this obscure case, as doing so may corrupt the outer Select
** statements AggInfo structure. */
if( sqlite3ExprIsConstantOrGroupBy(pWalker->pParse, pExpr, pS->pGroupBy)
&& ExprAlwaysFalse(pExpr)==0
&& pExpr->pAggInfo==0
){
sqlite3 *db = pWalker->pParse->db;
Expr *pNew = sqlite3Expr(db, TK_INTEGER, "1");
if( pNew ){
Expr *pWhere = pS->pWhere;
SWAP(Expr, *pNew, *pExpr);
pNew = sqlite3ExprAnd(pWalker->pParse, pWhere, pNew);
pS->pWhere = pNew;
pWalker->eCode = 1;
}
}
return WRC_Prune;
}
return WRC_Continue;
}
/*
** Transfer eligible terms from the HAVING clause of a query, which is
** processed after grouping, to the WHERE clause, which is processed before
** grouping. For example, the query:
**
** SELECT * FROM <tables> WHERE a=? GROUP BY b HAVING b=? AND c=?
**
** can be rewritten as:
**
** SELECT * FROM <tables> WHERE a=? AND b=? GROUP BY b HAVING c=?
**
** A term of the HAVING expression is eligible for transfer if it consists
** entirely of constants and expressions that are also GROUP BY terms that
** use the "BINARY" collation sequence.
*/
static void havingToWhere(Parse *pParse, Select *p){
Walker sWalker;
memset(&sWalker, 0, sizeof(sWalker));
sWalker.pParse = pParse;
sWalker.xExprCallback = havingToWhereExprCb;
sWalker.u.pSelect = p;
sqlite3WalkExpr(&sWalker, p->pHaving);
#if TREETRACE_ENABLED
if( sWalker.eCode && (sqlite3TreeTrace & 0x100)!=0 ){
TREETRACE(0x100,pParse,p,("Move HAVING terms into WHERE:\n"));
sqlite3TreeViewSelect(0, p, 0);
}
#endif
}
/*
** Check to see if the pThis entry of pTabList is a self-join of another view.
** Search FROM-clause entries in the range of iFirst..iEnd, including iFirst
** but stopping before iEnd.
**
** If pThis is a self-join, then return the SrcItem for the first other
** instance of that view found. If pThis is not a self-join then return 0.
*/
static SrcItem *isSelfJoinView(
SrcList *pTabList, /* Search for self-joins in this FROM clause */
SrcItem *pThis, /* Search for prior reference to this subquery */
int iFirst, int iEnd /* Range of FROM-clause entries to search. */
){
SrcItem *pItem;
assert( pThis->pSelect!=0 );
if( pThis->pSelect->selFlags & SF_PushDown ) return 0;
while( iFirst<iEnd ){
Select *pS1;
pItem = &pTabList->a[iFirst++];
if( pItem->pSelect==0 ) continue;
if( pItem->fg.viaCoroutine ) continue;
if( pItem->zName==0 ) continue;
assert( pItem->pTab!=0 );
assert( pThis->pTab!=0 );
if( pItem->pTab->pSchema!=pThis->pTab->pSchema ) continue;
if( sqlite3_stricmp(pItem->zName, pThis->zName)!=0 ) continue;
pS1 = pItem->pSelect;
if( pItem->pTab->pSchema==0 && pThis->pSelect->selId!=pS1->selId ){
/* The query flattener left two different CTE tables with identical
** names in the same FROM clause. */
continue;
}
if( pItem->pSelect->selFlags & SF_PushDown ){
/* The view was modified by some other optimization such as
** pushDownWhereTerms() */
continue;
}
return pItem;
}
return 0;
}
/*
** Deallocate a single AggInfo object
*/
static void agginfoFree(sqlite3 *db, AggInfo *p){
sqlite3DbFree(db, p->aCol);
sqlite3DbFree(db, p->aFunc);
sqlite3DbFreeNN(db, p);
}
#ifdef SQLITE_COUNTOFVIEW_OPTIMIZATION
/*
** Attempt to transform a query of the form
**
** SELECT count(*) FROM (SELECT x FROM t1 UNION ALL SELECT y FROM t2)
**
** Into this:
**
** SELECT (SELECT count(*) FROM t1)+(SELECT count(*) FROM t2)
**
** The transformation only works if all of the following are true:
**
** * The subquery is a UNION ALL of two or more terms
** * The subquery does not have a LIMIT clause
** * There is no WHERE or GROUP BY or HAVING clauses on the subqueries
** * The outer query is a simple count(*) with no WHERE clause or other
** extraneous syntax.
**
** Return TRUE if the optimization is undertaken.
*/
static int countOfViewOptimization(Parse *pParse, Select *p){
Select *pSub, *pPrior;
Expr *pExpr;
Expr *pCount;
sqlite3 *db;
if( (p->selFlags & SF_Aggregate)==0 ) return 0; /* This is an aggregate */
if( p->pEList->nExpr!=1 ) return 0; /* Single result column */
if( p->pWhere ) return 0;
if( p->pGroupBy ) return 0;
pExpr = p->pEList->a[0].pExpr;
if( pExpr->op!=TK_AGG_FUNCTION ) return 0; /* Result is an aggregate */
assert( ExprUseUToken(pExpr) );
if( sqlite3_stricmp(pExpr->u.zToken,"count") ) return 0; /* Is count() */
assert( ExprUseXList(pExpr) );
if( pExpr->x.pList!=0 ) return 0; /* Must be count(*) */
if( p->pSrc->nSrc!=1 ) return 0; /* One table in FROM */
pSub = p->pSrc->a[0].pSelect;
if( pSub==0 ) return 0; /* The FROM is a subquery */
if( pSub->pPrior==0 ) return 0; /* Must be a compound ry */
do{
if( pSub->op!=TK_ALL && pSub->pPrior ) return 0; /* Must be UNION ALL */
if( pSub->pWhere ) return 0; /* No WHERE clause */
if( pSub->pLimit ) return 0; /* No LIMIT clause */
if( pSub->selFlags & SF_Aggregate ) return 0; /* Not an aggregate */
pSub = pSub->pPrior; /* Repeat over compound */
}while( pSub );
/* If we reach this point then it is OK to perform the transformation */
db = pParse->db;
pCount = pExpr;
pExpr = 0;
pSub = p->pSrc->a[0].pSelect;
p->pSrc->a[0].pSelect = 0;
sqlite3SrcListDelete(db, p->pSrc);
p->pSrc = sqlite3DbMallocZero(pParse->db, sizeof(*p->pSrc));
while( pSub ){
Expr *pTerm;
pPrior = pSub->pPrior;
pSub->pPrior = 0;
pSub->pNext = 0;
pSub->selFlags |= SF_Aggregate;
pSub->selFlags &= ~SF_Compound;
pSub->nSelectRow = 0;
sqlite3ExprListDelete(db, pSub->pEList);
pTerm = pPrior ? sqlite3ExprDup(db, pCount, 0) : pCount;
pSub->pEList = sqlite3ExprListAppend(pParse, 0, pTerm);
pTerm = sqlite3PExpr(pParse, TK_SELECT, 0, 0);
sqlite3PExprAddSelect(pParse, pTerm, pSub);
if( pExpr==0 ){
pExpr = pTerm;
}else{
pExpr = sqlite3PExpr(pParse, TK_PLUS, pTerm, pExpr);
}
pSub = pPrior;
}
p->pEList->a[0].pExpr = pExpr;
p->selFlags &= ~SF_Aggregate;
#if TREETRACE_ENABLED
if( sqlite3TreeTrace & 0x200 ){
TREETRACE(0x200,pParse,p,("After count-of-view optimization:\n"));
sqlite3TreeViewSelect(0, p, 0);
}
#endif
return 1;
}
#endif /* SQLITE_COUNTOFVIEW_OPTIMIZATION */
/*
** If any term of pSrc, or any SF_NestedFrom sub-query, is not the same
** as pSrcItem but has the same alias as p0, then return true.
** Otherwise return false.
*/
static int sameSrcAlias(SrcItem *p0, SrcList *pSrc){
int i;
for(i=0; i<pSrc->nSrc; i++){
SrcItem *p1 = &pSrc->a[i];
if( p1==p0 ) continue;
if( p0->pTab==p1->pTab && 0==sqlite3_stricmp(p0->zAlias, p1->zAlias) ){
return 1;
}
if( p1->pSelect
&& (p1->pSelect->selFlags & SF_NestedFrom)!=0
&& sameSrcAlias(p0, p1->pSelect->pSrc)
){
return 1;
}
}
return 0;
}
/*
** Return TRUE (non-zero) if the i-th entry in the pTabList SrcList can
** be implemented as a co-routine. The i-th entry is guaranteed to be
** a subquery.
**
** The subquery is implemented as a co-routine if all of the following are
** true:
**
** (1) The subquery will likely be implemented in the outer loop of
** the query. This will be the case if any one of the following
** conditions hold:
** (a) The subquery is the only term in the FROM clause
** (b) The subquery is the left-most term and a CROSS JOIN or similar
** requires it to be the outer loop
** (c) All of the following are true:
** (i) The subquery is the left-most subquery in the FROM clause
** (ii) There is nothing that would prevent the subquery from
** being used as the outer loop if the sqlite3WhereBegin()
** routine nominates it to that position.
** (iii) The query is not a UPDATE ... FROM
** (2) The subquery is not a CTE that should be materialized because of
** the AS MATERIALIZED keywords
** (3) The subquery is not part of a left operand for a RIGHT JOIN
** (4) The SQLITE_Coroutine optimization disable flag is not set
** (5) The subquery is not self-joined
*/
static int fromClauseTermCanBeCoroutine(
Parse *pParse, /* Parsing context */
SrcList *pTabList, /* FROM clause */
int i, /* Which term of the FROM clause holds the subquery */
int selFlags /* Flags on the SELECT statement */
){
SrcItem *pItem = &pTabList->a[i];
if( pItem->fg.isCte && pItem->u2.pCteUse->eM10d==M10d_Yes ) return 0;/* (2) */
if( pTabList->a[0].fg.jointype & JT_LTORJ ) return 0; /* (3) */
if( OptimizationDisabled(pParse->db, SQLITE_Coroutines) ) return 0; /* (4) */
if( isSelfJoinView(pTabList, pItem, i+1, pTabList->nSrc)!=0 ){
return 0; /* (5) */
}
if( i==0 ){
if( pTabList->nSrc==1 ) return 1; /* (1a) */
if( pTabList->a[1].fg.jointype & JT_CROSS ) return 1; /* (1b) */
if( selFlags & SF_UpdateFrom ) return 0; /* (1c-iii) */
return 1;
}
if( selFlags & SF_UpdateFrom ) return 0; /* (1c-iii) */
while( 1 /*exit-by-break*/ ){
if( pItem->fg.jointype & (JT_OUTER|JT_CROSS) ) return 0; /* (1c-ii) */
if( i==0 ) break;
i--;
pItem--;
if( pItem->pSelect!=0 ) return 0; /* (1c-i) */
}
return 1;
}
/*
** Generate code for the SELECT statement given in the p argument.
**
** The results are returned according to the SelectDest structure.
** See comments in sqliteInt.h for further information.
**
** This routine returns the number of errors. If any errors are
** encountered, then an appropriate error message is left in
** pParse->zErrMsg.
**
** This routine does NOT free the Select structure passed in. The
** calling function needs to do that.
*/
int sqlite3Select(
Parse *pParse, /* The parser context */
Select *p, /* The SELECT statement being coded. */
SelectDest *pDest /* What to do with the query results */
){
int i, j; /* Loop counters */
WhereInfo *pWInfo; /* Return from sqlite3WhereBegin() */
Vdbe *v; /* The virtual machine under construction */
int isAgg; /* True for select lists like "count(*)" */
ExprList *pEList = 0; /* List of columns to extract. */
SrcList *pTabList; /* List of tables to select from */
Expr *pWhere; /* The WHERE clause. May be NULL */
ExprList *pGroupBy; /* The GROUP BY clause. May be NULL */
Expr *pHaving; /* The HAVING clause. May be NULL */
AggInfo *pAggInfo = 0; /* Aggregate information */
int rc = 1; /* Value to return from this function */
DistinctCtx sDistinct; /* Info on how to code the DISTINCT keyword */
SortCtx sSort; /* Info on how to code the ORDER BY clause */
int iEnd; /* Address of the end of the query */
sqlite3 *db; /* The database connection */
ExprList *pMinMaxOrderBy = 0; /* Added ORDER BY for min/max queries */
u8 minMaxFlag; /* Flag for min/max queries */
db = pParse->db;
assert( pParse==db->pParse );
v = sqlite3GetVdbe(pParse);
if( p==0 || pParse->nErr ){
return 1;
}
assert( db->mallocFailed==0 );
if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1;
#if TREETRACE_ENABLED
TREETRACE(0x1,pParse,p, ("begin processing:\n", pParse->addrExplain));
if( sqlite3TreeTrace & 0x10000 ){
if( (sqlite3TreeTrace & 0x10001)==0x10000 ){
sqlite3TreeViewLine(0, "In sqlite3Select() at %s:%d",
__FILE__, __LINE__);
}
sqlite3ShowSelect(p);
}
#endif
assert( p->pOrderBy==0 || pDest->eDest!=SRT_DistFifo );
assert( p->pOrderBy==0 || pDest->eDest!=SRT_Fifo );
assert( p->pOrderBy==0 || pDest->eDest!=SRT_DistQueue );
assert( p->pOrderBy==0 || pDest->eDest!=SRT_Queue );
if( IgnorableDistinct(pDest) ){
assert(pDest->eDest==SRT_Exists || pDest->eDest==SRT_Union ||
pDest->eDest==SRT_Except || pDest->eDest==SRT_Discard ||
pDest->eDest==SRT_DistQueue || pDest->eDest==SRT_DistFifo );
/* All of these destinations are also able to ignore the ORDER BY clause */
if( p->pOrderBy ){
#if TREETRACE_ENABLED
TREETRACE(0x800,pParse,p, ("dropping superfluous ORDER BY:\n"));
if( sqlite3TreeTrace & 0x800 ){
sqlite3TreeViewExprList(0, p->pOrderBy, 0, "ORDERBY");
}
#endif
sqlite3ParserAddCleanup(pParse,
(void(*)(sqlite3*,void*))sqlite3ExprListDelete,
p->pOrderBy);
testcase( pParse->earlyCleanup );
p->pOrderBy = 0;
}
p->selFlags &= ~SF_Distinct;
p->selFlags |= SF_NoopOrderBy;
}
sqlite3SelectPrep(pParse, p, 0);
if( pParse->nErr ){
goto select_end;
}
assert( db->mallocFailed==0 );
assert( p->pEList!=0 );
#if TREETRACE_ENABLED
if( sqlite3TreeTrace & 0x10 ){
TREETRACE(0x10,pParse,p, ("after name resolution:\n"));
sqlite3TreeViewSelect(0, p, 0);
}
#endif
/* If the SF_UFSrcCheck flag is set, then this function is being called
** as part of populating the temp table for an UPDATE...FROM statement.
** In this case, it is an error if the target object (pSrc->a[0]) name
** or alias is duplicated within FROM clause (pSrc->a[1..n]).
**
** Postgres disallows this case too. The reason is that some other
** systems handle this case differently, and not all the same way,
** which is just confusing. To avoid this, we follow PG's lead and
** disallow it altogether. */
if( p->selFlags & SF_UFSrcCheck ){
SrcItem *p0 = &p->pSrc->a[0];
if( sameSrcAlias(p0, p->pSrc) ){
sqlite3ErrorMsg(pParse,
"target object/alias may not appear in FROM clause: %s",
p0->zAlias ? p0->zAlias : p0->pTab->zName
);
goto select_end;
}
/* Clear the SF_UFSrcCheck flag. The check has already been performed,
** and leaving this flag set can cause errors if a compound sub-query
** in p->pSrc is flattened into this query and this function called
** again as part of compound SELECT processing. */
p->selFlags &= ~SF_UFSrcCheck;
}
if( pDest->eDest==SRT_Output ){
sqlite3GenerateColumnNames(pParse, p);
}
#ifndef SQLITE_OMIT_WINDOWFUNC
if( sqlite3WindowRewrite(pParse, p) ){
assert( pParse->nErr );
goto select_end;
}
#if TREETRACE_ENABLED
if( p->pWin && (sqlite3TreeTrace & 0x40)!=0 ){
TREETRACE(0x40,pParse,p, ("after window rewrite:\n"));
sqlite3TreeViewSelect(0, p, 0);
}
#endif
#endif /* SQLITE_OMIT_WINDOWFUNC */
pTabList = p->pSrc;
isAgg = (p->selFlags & SF_Aggregate)!=0;
memset(&sSort, 0, sizeof(sSort));
sSort.pOrderBy = p->pOrderBy;
/* Try to do various optimizations (flattening subqueries, and strength
** reduction of join operators) in the FROM clause up into the main query
*/
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
for(i=0; !p->pPrior && i<pTabList->nSrc; i++){
SrcItem *pItem = &pTabList->a[i];
Select *pSub = pItem->pSelect;
Table *pTab = pItem->pTab;
/* The expander should have already created transient Table objects
** even for FROM clause elements such as subqueries that do not correspond
** to a real table */
assert( pTab!=0 );
/* Convert LEFT JOIN into JOIN if there are terms of the right table
** of the LEFT JOIN used in the WHERE clause.
*/
if( (pItem->fg.jointype & (JT_LEFT|JT_RIGHT))==JT_LEFT
&& sqlite3ExprImpliesNonNullRow(p->pWhere, pItem->iCursor)
&& OptimizationEnabled(db, SQLITE_SimplifyJoin)
){
TREETRACE(0x1000,pParse,p,
("LEFT-JOIN simplifies to JOIN on term %d\n",i));
pItem->fg.jointype &= ~(JT_LEFT|JT_OUTER);
assert( pItem->iCursor>=0 );
unsetJoinExpr(p->pWhere, pItem->iCursor,
pTabList->a[0].fg.jointype & JT_LTORJ);
}
/* No futher action if this term of the FROM clause is no a subquery */
if( pSub==0 ) continue;
/* Catch mismatch in the declared columns of a view and the number of
** columns in the SELECT on the RHS */
if( pTab->nCol!=pSub->pEList->nExpr ){
sqlite3ErrorMsg(pParse, "expected %d columns for '%s' but got %d",
pTab->nCol, pTab->zName, pSub->pEList->nExpr);
goto select_end;
}
/* Do not try to flatten an aggregate subquery.
**
** Flattening an aggregate subquery is only possible if the outer query
** is not a join. But if the outer query is not a join, then the subquery
** will be implemented as a co-routine and there is no advantage to
** flattening in that case.
*/
if( (pSub->selFlags & SF_Aggregate)!=0 ) continue;
assert( pSub->pGroupBy==0 );
/* If a FROM-clause subquery has an ORDER BY clause that is not
** really doing anything, then delete it now so that it does not
** interfere with query flattening. See the discussion at
** https://sqlite.org/forum/forumpost/2d76f2bcf65d256a
**
** Beware of these cases where the ORDER BY clause may not be safely
** omitted:
**
** (1) There is also a LIMIT clause
** (2) The subquery was added to help with window-function
** processing
** (3) The subquery is in the FROM clause of an UPDATE
** (4) The outer query uses an aggregate function other than
** the built-in count(), min(), or max().
** (5) The ORDER BY isn't going to accomplish anything because
** one of:
** (a) The outer query has a different ORDER BY clause
** (b) The subquery is part of a join
** See forum post 062d576715d277c8
*/
if( pSub->pOrderBy!=0
&& (p->pOrderBy!=0 || pTabList->nSrc>1) /* Condition (5) */
&& pSub->pLimit==0 /* Condition (1) */
&& (pSub->selFlags & SF_OrderByReqd)==0 /* Condition (2) */
&& (p->selFlags & SF_OrderByReqd)==0 /* Condition (3) and (4) */
&& OptimizationEnabled(db, SQLITE_OmitOrderBy)
){
TREETRACE(0x800,pParse,p,
("omit superfluous ORDER BY on %r FROM-clause subquery\n",i+1));
sqlite3ParserAddCleanup(pParse,
(void(*)(sqlite3*,void*))sqlite3ExprListDelete,
pSub->pOrderBy);
pSub->pOrderBy = 0;
}
/* If the outer query contains a "complex" result set (that is,
** if the result set of the outer query uses functions or subqueries)
** and if the subquery contains an ORDER BY clause and if
** it will be implemented as a co-routine, then do not flatten. This
** restriction allows SQL constructs like this:
**
** SELECT expensive_function(x)
** FROM (SELECT x FROM tab ORDER BY y LIMIT 10);
**
** The expensive_function() is only computed on the 10 rows that
** are output, rather than every row of the table.
**
** The requirement that the outer query have a complex result set
** means that flattening does occur on simpler SQL constraints without
** the expensive_function() like:
**
** SELECT x FROM (SELECT x FROM tab ORDER BY y LIMIT 10);
*/
if( pSub->pOrderBy!=0
&& i==0
&& (p->selFlags & SF_ComplexResult)!=0
&& (pTabList->nSrc==1
|| (pTabList->a[1].fg.jointype&(JT_OUTER|JT_CROSS))!=0)
){
continue;
}
if( flattenSubquery(pParse, p, i, isAgg) ){
if( pParse->nErr ) goto select_end;
/* This subquery can be absorbed into its parent. */
i = -1;
}
pTabList = p->pSrc;
if( db->mallocFailed ) goto select_end;
if( !IgnorableOrderby(pDest) ){
sSort.pOrderBy = p->pOrderBy;
}
}
#endif
#ifndef SQLITE_OMIT_COMPOUND_SELECT
/* Handle compound SELECT statements using the separate multiSelect()
** procedure.
*/
if( p->pPrior ){
rc = multiSelect(pParse, p, pDest);
#if TREETRACE_ENABLED
TREETRACE(0x400,pParse,p,("end compound-select processing\n"));
if( (sqlite3TreeTrace & 0x400)!=0 && ExplainQueryPlanParent(pParse)==0 ){
sqlite3TreeViewSelect(0, p, 0);
}
#endif
if( p->pNext==0 ) ExplainQueryPlanPop(pParse);
return rc;
}
#endif
/* Do the WHERE-clause constant propagation optimization if this is
** a join. No need to speed time on this operation for non-join queries
** as the equivalent optimization will be handled by query planner in
** sqlite3WhereBegin().
*/
if( p->pWhere!=0
&& p->pWhere->op==TK_AND
&& OptimizationEnabled(db, SQLITE_PropagateConst)
&& propagateConstants(pParse, p)
){
#if TREETRACE_ENABLED
if( sqlite3TreeTrace & 0x2000 ){
TREETRACE(0x2000,pParse,p,("After constant propagation:\n"));
sqlite3TreeViewSelect(0, p, 0);
}
#endif
}else{
TREETRACE(0x2000,pParse,p,("Constant propagation not helpful\n"));
}
#ifdef SQLITE_COUNTOFVIEW_OPTIMIZATION
if( OptimizationEnabled(db, SQLITE_QueryFlattener|SQLITE_CountOfView)
&& countOfViewOptimization(pParse, p)
){
if( db->mallocFailed ) goto select_end;
pEList = p->pEList;
pTabList = p->pSrc;
}
#endif
/* For each term in the FROM clause, do two things:
** (1) Authorized unreferenced tables
** (2) Generate code for all sub-queries
*/
for(i=0; i<pTabList->nSrc; i++){
SrcItem *pItem = &pTabList->a[i];
SrcItem *pPrior;
SelectDest dest;
Select *pSub;
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
const char *zSavedAuthContext;
#endif
/* Issue SQLITE_READ authorizations with a fake column name for any
** tables that are referenced but from which no values are extracted.
** Examples of where these kinds of null SQLITE_READ authorizations
** would occur:
**
** SELECT count(*) FROM t1; -- SQLITE_READ t1.""
** SELECT t1.* FROM t1, t2; -- SQLITE_READ t2.""
**
** The fake column name is an empty string. It is possible for a table to
** have a column named by the empty string, in which case there is no way to
** distinguish between an unreferenced table and an actual reference to the
** "" column. The original design was for the fake column name to be a NULL,
** which would be unambiguous. But legacy authorization callbacks might
** assume the column name is non-NULL and segfault. The use of an empty
** string for the fake column name seems safer.
*/
if( pItem->colUsed==0 && pItem->zName!=0 ){
sqlite3AuthCheck(pParse, SQLITE_READ, pItem->zName, "", pItem->zDatabase);
}
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
/* Generate code for all sub-queries in the FROM clause
*/
pSub = pItem->pSelect;
if( pSub==0 ) continue;
/* The code for a subquery should only be generated once. */
assert( pItem->addrFillSub==0 );
/* Increment Parse.nHeight by the height of the largest expression
** tree referred to by this, the parent select. The child select
** may contain expression trees of at most
** (SQLITE_MAX_EXPR_DEPTH-Parse.nHeight) height. This is a bit
** more conservative than necessary, but much easier than enforcing
** an exact limit.
*/
pParse->nHeight += sqlite3SelectExprHeight(p);
/* Make copies of constant WHERE-clause terms in the outer query down
** inside the subquery. This can help the subquery to run more efficiently.
*/
if( OptimizationEnabled(db, SQLITE_PushDown)
&& (pItem->fg.isCte==0
|| (pItem->u2.pCteUse->eM10d!=M10d_Yes && pItem->u2.pCteUse->nUse<2))
&& pushDownWhereTerms(pParse, pSub, p->pWhere, pItem)
){
#if TREETRACE_ENABLED
if( sqlite3TreeTrace & 0x4000 ){
TREETRACE(0x4000,pParse,p,
("After WHERE-clause push-down into subquery %d:\n", pSub->selId));
sqlite3TreeViewSelect(0, p, 0);
}
#endif
assert( pItem->pSelect && (pItem->pSelect->selFlags & SF_PushDown)!=0 );
}else{
TREETRACE(0x4000,pParse,p,("Push-down not possible\n"));
}
zSavedAuthContext = pParse->zAuthContext;
pParse->zAuthContext = pItem->zName;
/* Generate code to implement the subquery
*/
if( fromClauseTermCanBeCoroutine(pParse, pTabList, i, p->selFlags) ){
/* Implement a co-routine that will return a single row of the result
** set on each invocation.
*/
int addrTop = sqlite3VdbeCurrentAddr(v)+1;
pItem->regReturn = ++pParse->nMem;
sqlite3VdbeAddOp3(v, OP_InitCoroutine, pItem->regReturn, 0, addrTop);
VdbeComment((v, "%!S", pItem));
pItem->addrFillSub = addrTop;
sqlite3SelectDestInit(&dest, SRT_Coroutine, pItem->regReturn);
ExplainQueryPlan((pParse, 1, "CO-ROUTINE %!S", pItem));
sqlite3Select(pParse, pSub, &dest);
pItem->pTab->nRowLogEst = pSub->nSelectRow;
pItem->fg.viaCoroutine = 1;
pItem->regResult = dest.iSdst;
sqlite3VdbeEndCoroutine(v, pItem->regReturn);
sqlite3VdbeJumpHere(v, addrTop-1);
sqlite3ClearTempRegCache(pParse);
}else if( pItem->fg.isCte && pItem->u2.pCteUse->addrM9e>0 ){
/* This is a CTE for which materialization code has already been
** generated. Invoke the subroutine to compute the materialization,
** the make the pItem->iCursor be a copy of the ephemerial table that
** holds the result of the materialization. */
CteUse *pCteUse = pItem->u2.pCteUse;
sqlite3VdbeAddOp2(v, OP_Gosub, pCteUse->regRtn, pCteUse->addrM9e);
if( pItem->iCursor!=pCteUse->iCur ){
sqlite3VdbeAddOp2(v, OP_OpenDup, pItem->iCursor, pCteUse->iCur);
VdbeComment((v, "%!S", pItem));
}
pSub->nSelectRow = pCteUse->nRowEst;
}else if( (pPrior = isSelfJoinView(pTabList, pItem, 0, i))!=0 ){
/* This view has already been materialized by a prior entry in
** this same FROM clause. Reuse it. */
if( pPrior->addrFillSub ){
sqlite3VdbeAddOp2(v, OP_Gosub, pPrior->regReturn, pPrior->addrFillSub);
}
sqlite3VdbeAddOp2(v, OP_OpenDup, pItem->iCursor, pPrior->iCursor);
pSub->nSelectRow = pPrior->pSelect->nSelectRow;
}else{
/* Materialize the view. If the view is not correlated, generate a
** subroutine to do the materialization so that subsequent uses of
** the same view can reuse the materialization. */
int topAddr;
int onceAddr = 0;
#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
int addrExplain;
#endif
pItem->regReturn = ++pParse->nMem;
topAddr = sqlite3VdbeAddOp0(v, OP_Goto);
pItem->addrFillSub = topAddr+1;
pItem->fg.isMaterialized = 1;
if( pItem->fg.isCorrelated==0 ){
/* If the subquery is not correlated and if we are not inside of
** a trigger, then we only need to compute the value of the subquery
** once. */
onceAddr = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v);
VdbeComment((v, "materialize %!S", pItem));
}else{
VdbeNoopComment((v, "materialize %!S", pItem));
}
sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor);
ExplainQueryPlan2(addrExplain, (pParse, 1, "MATERIALIZE %!S", pItem));
sqlite3Select(pParse, pSub, &dest);
pItem->pTab->nRowLogEst = pSub->nSelectRow;
if( onceAddr ) sqlite3VdbeJumpHere(v, onceAddr);
sqlite3VdbeAddOp2(v, OP_Return, pItem->regReturn, topAddr+1);
VdbeComment((v, "end %!S", pItem));
sqlite3VdbeScanStatusRange(v, addrExplain, addrExplain, -1);
sqlite3VdbeJumpHere(v, topAddr);
sqlite3ClearTempRegCache(pParse);
if( pItem->fg.isCte && pItem->fg.isCorrelated==0 ){
CteUse *pCteUse = pItem->u2.pCteUse;
pCteUse->addrM9e = pItem->addrFillSub;
pCteUse->regRtn = pItem->regReturn;
pCteUse->iCur = pItem->iCursor;
pCteUse->nRowEst = pSub->nSelectRow;
}
}
if( db->mallocFailed ) goto select_end;
pParse->nHeight -= sqlite3SelectExprHeight(p);
pParse->zAuthContext = zSavedAuthContext;
#endif
}
/* Various elements of the SELECT copied into local variables for
** convenience */
pEList = p->pEList;
pWhere = p->pWhere;
pGroupBy = p->pGroupBy;
pHaving = p->pHaving;
sDistinct.isTnct = (p->selFlags & SF_Distinct)!=0;
#if TREETRACE_ENABLED
if( sqlite3TreeTrace & 0x8000 ){
TREETRACE(0x8000,pParse,p,("After all FROM-clause analysis:\n"));
sqlite3TreeViewSelect(0, p, 0);
}
#endif
/* If the query is DISTINCT with an ORDER BY but is not an aggregate, and
** if the select-list is the same as the ORDER BY list, then this query
** can be rewritten as a GROUP BY. In other words, this:
**
** SELECT DISTINCT xyz FROM ... ORDER BY xyz
**
** is transformed to:
**
** SELECT xyz FROM ... GROUP BY xyz ORDER BY xyz
**
** The second form is preferred as a single index (or temp-table) may be
** used for both the ORDER BY and DISTINCT processing. As originally
** written the query must use a temp-table for at least one of the ORDER
** BY and DISTINCT, and an index or separate temp-table for the other.
*/
if( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct
&& sqlite3ExprListCompare(sSort.pOrderBy, pEList, -1)==0
#ifndef SQLITE_OMIT_WINDOWFUNC
&& p->pWin==0
#endif
){
p->selFlags &= ~SF_Distinct;
pGroupBy = p->pGroupBy = sqlite3ExprListDup(db, pEList, 0);
p->selFlags |= SF_Aggregate;
/* Notice that even thought SF_Distinct has been cleared from p->selFlags,
** the sDistinct.isTnct is still set. Hence, isTnct represents the
** original setting of the SF_Distinct flag, not the current setting */
assert( sDistinct.isTnct );
sDistinct.isTnct = 2;
#if TREETRACE_ENABLED
if( sqlite3TreeTrace & 0x20000 ){
TREETRACE(0x20000,pParse,p,("Transform DISTINCT into GROUP BY:\n"));
sqlite3TreeViewSelect(0, p, 0);
}
#endif
}
/* If there is an ORDER BY clause, then create an ephemeral index to
** do the sorting. But this sorting ephemeral index might end up
** being unused if the data can be extracted in pre-sorted order.
** If that is the case, then the OP_OpenEphemeral instruction will be
** changed to an OP_Noop once we figure out that the sorting index is
** not needed. The sSort.addrSortIndex variable is used to facilitate
** that change.
*/
if( sSort.pOrderBy ){
KeyInfo *pKeyInfo;
pKeyInfo = sqlite3KeyInfoFromExprList(
pParse, sSort.pOrderBy, 0, pEList->nExpr);
sSort.iECursor = pParse->nTab++;
sSort.addrSortIndex =
sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
sSort.iECursor, sSort.pOrderBy->nExpr+1+pEList->nExpr, 0,
(char*)pKeyInfo, P4_KEYINFO
);
}else{
sSort.addrSortIndex = -1;
}
/* If the output is destined for a temporary table, open that table.
*/
if( pDest->eDest==SRT_EphemTab ){
sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pDest->iSDParm, pEList->nExpr);
if( p->selFlags & SF_NestedFrom ){
/* Delete or NULL-out result columns that will never be used */
int ii;
for(ii=pEList->nExpr-1; ii>0 && pEList->a[ii].fg.bUsed==0; ii--){
sqlite3ExprDelete(db, pEList->a[ii].pExpr);
sqlite3DbFree(db, pEList->a[ii].zEName);
pEList->nExpr--;
}
for(ii=0; ii<pEList->nExpr; ii++){
if( pEList->a[ii].fg.bUsed==0 ) pEList->a[ii].pExpr->op = TK_NULL;
}
}
}
/* Set the limiter.
*/
iEnd = sqlite3VdbeMakeLabel(pParse);
if( (p->selFlags & SF_FixedLimit)==0 ){
p->nSelectRow = 320; /* 4 billion rows */
}
if( p->pLimit ) computeLimitRegisters(pParse, p, iEnd);
if( p->iLimit==0 && sSort.addrSortIndex>=0 ){
sqlite3VdbeChangeOpcode(v, sSort.addrSortIndex, OP_SorterOpen);
sSort.sortFlags |= SORTFLAG_UseSorter;
}
/* Open an ephemeral index to use for the distinct set.
*/
if( p->selFlags & SF_Distinct ){
sDistinct.tabTnct = pParse->nTab++;
sDistinct.addrTnct = sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
sDistinct.tabTnct, 0, 0,
(char*)sqlite3KeyInfoFromExprList(pParse, p->pEList,0,0),
P4_KEYINFO);
sqlite3VdbeChangeP5(v, BTREE_UNORDERED);
sDistinct.eTnctType = WHERE_DISTINCT_UNORDERED;
}else{
sDistinct.eTnctType = WHERE_DISTINCT_NOOP;
}
if( !isAgg && pGroupBy==0 ){
/* No aggregate functions and no GROUP BY clause */
u16 wctrlFlags = (sDistinct.isTnct ? WHERE_WANT_DISTINCT : 0)
| (p->selFlags & SF_FixedLimit);
#ifndef SQLITE_OMIT_WINDOWFUNC
Window *pWin = p->pWin; /* Main window object (or NULL) */
if( pWin ){
sqlite3WindowCodeInit(pParse, p);
}
#endif
assert( WHERE_USE_LIMIT==SF_FixedLimit );
/* Begin the database scan. */
TREETRACE(0x2,pParse,p,("WhereBegin\n"));
pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, sSort.pOrderBy,
p->pEList, p, wctrlFlags, p->nSelectRow);
if( pWInfo==0 ) goto select_end;
if( sqlite3WhereOutputRowCount(pWInfo) < p->nSelectRow ){
p->nSelectRow = sqlite3WhereOutputRowCount(pWInfo);
}
if( sDistinct.isTnct && sqlite3WhereIsDistinct(pWInfo) ){
sDistinct.eTnctType = sqlite3WhereIsDistinct(pWInfo);
}
if( sSort.pOrderBy ){
sSort.nOBSat = sqlite3WhereIsOrdered(pWInfo);
sSort.labelOBLopt = sqlite3WhereOrderByLimitOptLabel(pWInfo);
if( sSort.nOBSat==sSort.pOrderBy->nExpr ){
sSort.pOrderBy = 0;
}
}
TREETRACE(0x2,pParse,p,("WhereBegin returns\n"));
/* If sorting index that was created by a prior OP_OpenEphemeral
** instruction ended up not being needed, then change the OP_OpenEphemeral
** into an OP_Noop.
*/
if( sSort.addrSortIndex>=0 && sSort.pOrderBy==0 ){
sqlite3VdbeChangeToNoop(v, sSort.addrSortIndex);
}
assert( p->pEList==pEList );
#ifndef SQLITE_OMIT_WINDOWFUNC
if( pWin ){
int addrGosub = sqlite3VdbeMakeLabel(pParse);
int iCont = sqlite3VdbeMakeLabel(pParse);
int iBreak = sqlite3VdbeMakeLabel(pParse);
int regGosub = ++pParse->nMem;
sqlite3WindowCodeStep(pParse, p, pWInfo, regGosub, addrGosub);
sqlite3VdbeAddOp2(v, OP_Goto, 0, iBreak);
sqlite3VdbeResolveLabel(v, addrGosub);
VdbeNoopComment((v, "inner-loop subroutine"));
sSort.labelOBLopt = 0;
selectInnerLoop(pParse, p, -1, &sSort, &sDistinct, pDest, iCont, iBreak);
sqlite3VdbeResolveLabel(v, iCont);
sqlite3VdbeAddOp1(v, OP_Return, regGosub);
VdbeComment((v, "end inner-loop subroutine"));
sqlite3VdbeResolveLabel(v, iBreak);
}else
#endif /* SQLITE_OMIT_WINDOWFUNC */
{
/* Use the standard inner loop. */
selectInnerLoop(pParse, p, -1, &sSort, &sDistinct, pDest,
sqlite3WhereContinueLabel(pWInfo),
sqlite3WhereBreakLabel(pWInfo));
/* End the database scan loop.
*/
TREETRACE(0x2,pParse,p,("WhereEnd\n"));
sqlite3WhereEnd(pWInfo);
}
}else{
/* This case when there exist aggregate functions or a GROUP BY clause
** or both */
NameContext sNC; /* Name context for processing aggregate information */
int iAMem; /* First Mem address for storing current GROUP BY */
int iBMem; /* First Mem address for previous GROUP BY */
int iUseFlag; /* Mem address holding flag indicating that at least
** one row of the input to the aggregator has been
** processed */
int iAbortFlag; /* Mem address which causes query abort if positive */
int groupBySort; /* Rows come from source in GROUP BY order */
int addrEnd; /* End of processing for this SELECT */
int sortPTab = 0; /* Pseudotable used to decode sorting results */
int sortOut = 0; /* Output register from the sorter */
int orderByGrp = 0; /* True if the GROUP BY and ORDER BY are the same */
/* Remove any and all aliases between the result set and the
** GROUP BY clause.
*/
if( pGroupBy ){
int k; /* Loop counter */
struct ExprList_item *pItem; /* For looping over expression in a list */
for(k=p->pEList->nExpr, pItem=p->pEList->a; k>0; k--, pItem++){
pItem->u.x.iAlias = 0;
}
for(k=pGroupBy->nExpr, pItem=pGroupBy->a; k>0; k--, pItem++){
pItem->u.x.iAlias = 0;
}
assert( 66==sqlite3LogEst(100) );
if( p->nSelectRow>66 ) p->nSelectRow = 66;
/* If there is both a GROUP BY and an ORDER BY clause and they are
** identical, then it may be possible to disable the ORDER BY clause
** on the grounds that the GROUP BY will cause elements to come out
** in the correct order. It also may not - the GROUP BY might use a
** database index that causes rows to be grouped together as required
** but not actually sorted. Either way, record the fact that the
** ORDER BY and GROUP BY clauses are the same by setting the orderByGrp
** variable. */
if( sSort.pOrderBy && pGroupBy->nExpr==sSort.pOrderBy->nExpr ){
int ii;
/* The GROUP BY processing doesn't care whether rows are delivered in
** ASC or DESC order - only that each group is returned contiguously.
** So set the ASC/DESC flags in the GROUP BY to match those in the
** ORDER BY to maximize the chances of rows being delivered in an
** order that makes the ORDER BY redundant. */
for(ii=0; ii<pGroupBy->nExpr; ii++){
u8 sortFlags;
sortFlags = sSort.pOrderBy->a[ii].fg.sortFlags & KEYINFO_ORDER_DESC;
pGroupBy->a[ii].fg.sortFlags = sortFlags;
}
if( sqlite3ExprListCompare(pGroupBy, sSort.pOrderBy, -1)==0 ){
orderByGrp = 1;
}
}
}else{
assert( 0==sqlite3LogEst(1) );
p->nSelectRow = 0;
}
/* Create a label to jump to when we want to abort the query */
addrEnd = sqlite3VdbeMakeLabel(pParse);
/* Convert TK_COLUMN nodes into TK_AGG_COLUMN and make entries in
** sAggInfo for all TK_AGG_FUNCTION nodes in expressions of the
** SELECT statement.
*/
pAggInfo = sqlite3DbMallocZero(db, sizeof(*pAggInfo) );
if( pAggInfo ){
sqlite3ParserAddCleanup(pParse,
(void(*)(sqlite3*,void*))agginfoFree, pAggInfo);
testcase( pParse->earlyCleanup );
}
if( db->mallocFailed ){
goto select_end;
}
pAggInfo->selId = p->selId;
#ifdef SQLITE_DEBUG
pAggInfo->pSelect = p;
#endif
memset(&sNC, 0, sizeof(sNC));
sNC.pParse = pParse;
sNC.pSrcList = pTabList;
sNC.uNC.pAggInfo = pAggInfo;
VVA_ONLY( sNC.ncFlags = NC_UAggInfo; )
pAggInfo->nSortingColumn = pGroupBy ? pGroupBy->nExpr : 0;
pAggInfo->pGroupBy = pGroupBy;
sqlite3ExprAnalyzeAggList(&sNC, pEList);
sqlite3ExprAnalyzeAggList(&sNC, sSort.pOrderBy);
if( pHaving ){
if( pGroupBy ){
assert( pWhere==p->pWhere );
assert( pHaving==p->pHaving );
assert( pGroupBy==p->pGroupBy );
havingToWhere(pParse, p);
pWhere = p->pWhere;
}
sqlite3ExprAnalyzeAggregates(&sNC, pHaving);
}
pAggInfo->nAccumulator = pAggInfo->nColumn;
if( p->pGroupBy==0 && p->pHaving==0 && pAggInfo->nFunc==1 ){
minMaxFlag = minMaxQuery(db, pAggInfo->aFunc[0].pFExpr, &pMinMaxOrderBy);
}else{
minMaxFlag = WHERE_ORDERBY_NORMAL;
}
analyzeAggFuncArgs(pAggInfo, &sNC);
if( db->mallocFailed ) goto select_end;
#if TREETRACE_ENABLED
if( sqlite3TreeTrace & 0x20 ){
TREETRACE(0x20,pParse,p,("After aggregate analysis %p:\n", pAggInfo));
sqlite3TreeViewSelect(0, p, 0);
if( minMaxFlag ){
sqlite3DebugPrintf("MIN/MAX Optimization (0x%02x) adds:\n", minMaxFlag);
sqlite3TreeViewExprList(0, pMinMaxOrderBy, 0, "ORDERBY");
}
printAggInfo(pAggInfo);
}
#endif
/* Processing for aggregates with GROUP BY is very different and
** much more complex than aggregates without a GROUP BY.
*/
if( pGroupBy ){
KeyInfo *pKeyInfo; /* Keying information for the group by clause */
int addr1; /* A-vs-B comparision jump */
int addrOutputRow; /* Start of subroutine that outputs a result row */
int regOutputRow; /* Return address register for output subroutine */
int addrSetAbort; /* Set the abort flag and return */
int addrTopOfLoop; /* Top of the input loop */
int addrSortingIdx; /* The OP_OpenEphemeral for the sorting index */
int addrReset; /* Subroutine for resetting the accumulator */
int regReset; /* Return address register for reset subroutine */
ExprList *pDistinct = 0;
u16 distFlag = 0;
int eDist = WHERE_DISTINCT_NOOP;
if( pAggInfo->nFunc==1
&& pAggInfo->aFunc[0].iDistinct>=0
&& ALWAYS(pAggInfo->aFunc[0].pFExpr!=0)
&& ALWAYS(ExprUseXList(pAggInfo->aFunc[0].pFExpr))
&& pAggInfo->aFunc[0].pFExpr->x.pList!=0
){
Expr *pExpr = pAggInfo->aFunc[0].pFExpr->x.pList->a[0].pExpr;
pExpr = sqlite3ExprDup(db, pExpr, 0);
pDistinct = sqlite3ExprListDup(db, pGroupBy, 0);
pDistinct = sqlite3ExprListAppend(pParse, pDistinct, pExpr);
distFlag = pDistinct ? (WHERE_WANT_DISTINCT|WHERE_AGG_DISTINCT) : 0;
}
/* If there is a GROUP BY clause we might need a sorting index to
** implement it. Allocate that sorting index now. If it turns out
** that we do not need it after all, the OP_SorterOpen instruction
** will be converted into a Noop.
*/
pAggInfo->sortingIdx = pParse->nTab++;
pKeyInfo = sqlite3KeyInfoFromExprList(pParse, pGroupBy,
0, pAggInfo->nColumn);
addrSortingIdx = sqlite3VdbeAddOp4(v, OP_SorterOpen,
pAggInfo->sortingIdx, pAggInfo->nSortingColumn,
0, (char*)pKeyInfo, P4_KEYINFO);
/* Initialize memory locations used by GROUP BY aggregate processing
*/
iUseFlag = ++pParse->nMem;
iAbortFlag = ++pParse->nMem;
regOutputRow = ++pParse->nMem;
addrOutputRow = sqlite3VdbeMakeLabel(pParse);
regReset = ++pParse->nMem;
addrReset = sqlite3VdbeMakeLabel(pParse);
iAMem = pParse->nMem + 1;
pParse->nMem += pGroupBy->nExpr;
iBMem = pParse->nMem + 1;
pParse->nMem += pGroupBy->nExpr;
sqlite3VdbeAddOp2(v, OP_Integer, 0, iAbortFlag);
VdbeComment((v, "clear abort flag"));
sqlite3VdbeAddOp3(v, OP_Null, 0, iAMem, iAMem+pGroupBy->nExpr-1);
/* Begin a loop that will extract all source rows in GROUP BY order.
** This might involve two separate loops with an OP_Sort in between, or
** it might be a single loop that uses an index to extract information
** in the right order to begin with.
*/
sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset);
TREETRACE(0x2,pParse,p,("WhereBegin\n"));
pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pGroupBy, pDistinct,
p, (sDistinct.isTnct==2 ? WHERE_DISTINCTBY : WHERE_GROUPBY)
| (orderByGrp ? WHERE_SORTBYGROUP : 0) | distFlag, 0
);
if( pWInfo==0 ){
sqlite3ExprListDelete(db, pDistinct);
goto select_end;
}
if( pParse->pIdxEpr ){
optimizeAggregateUseOfIndexedExpr(pParse, p, pAggInfo, &sNC);
}
assignAggregateRegisters(pParse, pAggInfo);
eDist = sqlite3WhereIsDistinct(pWInfo);
TREETRACE(0x2,pParse,p,("WhereBegin returns\n"));
if( sqlite3WhereIsOrdered(pWInfo)==pGroupBy->nExpr ){
/* The optimizer is able to deliver rows in group by order so
** we do not have to sort. The OP_OpenEphemeral table will be
** cancelled later because we still need to use the pKeyInfo
*/
groupBySort = 0;
}else{
/* Rows are coming out in undetermined order. We have to push
** each row into a sorting index, terminate the first loop,
** then loop over the sorting index in order to get the output
** in sorted order
*/
int regBase;
int regRecord;
int nCol;
int nGroupBy;
explainTempTable(pParse,
(sDistinct.isTnct && (p->selFlags&SF_Distinct)==0) ?
"DISTINCT" : "GROUP BY");
groupBySort = 1;
nGroupBy = pGroupBy->nExpr;
nCol = nGroupBy;
j = nGroupBy;
for(i=0; i<pAggInfo->nColumn; i++){
if( pAggInfo->aCol[i].iSorterColumn>=j ){
nCol++;
j++;
}
}
regBase = sqlite3GetTempRange(pParse, nCol);
sqlite3ExprCodeExprList(pParse, pGroupBy, regBase, 0, 0);
j = nGroupBy;
pAggInfo->directMode = 1;
for(i=0; i<pAggInfo->nColumn; i++){
struct AggInfo_col *pCol = &pAggInfo->aCol[i];
if( pCol->iSorterColumn>=j ){
sqlite3ExprCode(pParse, pCol->pCExpr, j + regBase);
j++;
}
}
pAggInfo->directMode = 0;
regRecord = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol, regRecord);
sqlite3VdbeAddOp2(v, OP_SorterInsert, pAggInfo->sortingIdx, regRecord);
sqlite3ReleaseTempReg(pParse, regRecord);
sqlite3ReleaseTempRange(pParse, regBase, nCol);
TREETRACE(0x2,pParse,p,("WhereEnd\n"));
sqlite3WhereEnd(pWInfo);
pAggInfo->sortingIdxPTab = sortPTab = pParse->nTab++;
sortOut = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_OpenPseudo, sortPTab, sortOut, nCol);
sqlite3VdbeAddOp2(v, OP_SorterSort, pAggInfo->sortingIdx, addrEnd);
VdbeComment((v, "GROUP BY sort")); VdbeCoverage(v);
pAggInfo->useSortingIdx = 1;
}
/* If there entries in pAgggInfo->aFunc[] that contain subexpressions
** that are indexed (and that were previously identified and tagged
** in optimizeAggregateUseOfIndexedExpr()) then those subexpressions
** must now be converted into a TK_AGG_COLUMN node so that the value
** is correctly pulled from the index rather than being recomputed. */
if( pParse->pIdxEpr ){
aggregateConvertIndexedExprRefToColumn(pAggInfo);
#if TREETRACE_ENABLED
if( sqlite3TreeTrace & 0x20 ){
TREETRACE(0x20, pParse, p,
("AggInfo function expressions converted to reference index\n"));
sqlite3TreeViewSelect(0, p, 0);
printAggInfo(pAggInfo);
}
#endif
}
/* If the index or temporary table used by the GROUP BY sort
** will naturally deliver rows in the order required by the ORDER BY
** clause, cancel the ephemeral table open coded earlier.
**
** This is an optimization - the correct answer should result regardless.
** Use the SQLITE_GroupByOrder flag with SQLITE_TESTCTRL_OPTIMIZER to
** disable this optimization for testing purposes. */
if( orderByGrp && OptimizationEnabled(db, SQLITE_GroupByOrder)
&& (groupBySort || sqlite3WhereIsSorted(pWInfo))
){
sSort.pOrderBy = 0;
sqlite3VdbeChangeToNoop(v, sSort.addrSortIndex);
}
/* Evaluate the current GROUP BY terms and store in b0, b1, b2...
** (b0 is memory location iBMem+0, b1 is iBMem+1, and so forth)
** Then compare the current GROUP BY terms against the GROUP BY terms
** from the previous row currently stored in a0, a1, a2...
*/
addrTopOfLoop = sqlite3VdbeCurrentAddr(v);
if( groupBySort ){
sqlite3VdbeAddOp3(v, OP_SorterData, pAggInfo->sortingIdx,
sortOut, sortPTab);
}
for(j=0; j<pGroupBy->nExpr; j++){
if( groupBySort ){
sqlite3VdbeAddOp3(v, OP_Column, sortPTab, j, iBMem+j);
}else{
pAggInfo->directMode = 1;
sqlite3ExprCode(pParse, pGroupBy->a[j].pExpr, iBMem+j);
}
}
sqlite3VdbeAddOp4(v, OP_Compare, iAMem, iBMem, pGroupBy->nExpr,
(char*)sqlite3KeyInfoRef(pKeyInfo), P4_KEYINFO);
addr1 = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp3(v, OP_Jump, addr1+1, 0, addr1+1); VdbeCoverage(v);
/* Generate code that runs whenever the GROUP BY changes.
** Changes in the GROUP BY are detected by the previous code
** block. If there were no changes, this block is skipped.
**
** This code copies current group by terms in b0,b1,b2,...
** over to a0,a1,a2. It then calls the output subroutine
** and resets the aggregate accumulator registers in preparation
** for the next GROUP BY batch.
*/
sqlite3ExprCodeMove(pParse, iBMem, iAMem, pGroupBy->nExpr);
sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow);
VdbeComment((v, "output one row"));
sqlite3VdbeAddOp2(v, OP_IfPos, iAbortFlag, addrEnd); VdbeCoverage(v);
VdbeComment((v, "check abort flag"));
sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset);
VdbeComment((v, "reset accumulator"));
/* Update the aggregate accumulators based on the content of
** the current row
*/
sqlite3VdbeJumpHere(v, addr1);
updateAccumulator(pParse, iUseFlag, pAggInfo, eDist);
sqlite3VdbeAddOp2(v, OP_Integer, 1, iUseFlag);
VdbeComment((v, "indicate data in accumulator"));
/* End of the loop
*/
if( groupBySort ){
sqlite3VdbeAddOp2(v, OP_SorterNext, pAggInfo->sortingIdx,addrTopOfLoop);
VdbeCoverage(v);
}else{
TREETRACE(0x2,pParse,p,("WhereEnd\n"));
sqlite3WhereEnd(pWInfo);
sqlite3VdbeChangeToNoop(v, addrSortingIdx);
}
sqlite3ExprListDelete(db, pDistinct);
/* Output the final row of result
*/
sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow);
VdbeComment((v, "output final row"));
/* Jump over the subroutines
*/
sqlite3VdbeGoto(v, addrEnd);
/* Generate a subroutine that outputs a single row of the result
** set. This subroutine first looks at the iUseFlag. If iUseFlag
** is less than or equal to zero, the subroutine is a no-op. If
** the processing calls for the query to abort, this subroutine
** increments the iAbortFlag memory location before returning in
** order to signal the caller to abort.
*/
addrSetAbort = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp2(v, OP_Integer, 1, iAbortFlag);
VdbeComment((v, "set abort flag"));
sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
sqlite3VdbeResolveLabel(v, addrOutputRow);
addrOutputRow = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp2(v, OP_IfPos, iUseFlag, addrOutputRow+2);
VdbeCoverage(v);
VdbeComment((v, "Groupby result generator entry point"));
sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
finalizeAggFunctions(pParse, pAggInfo);
sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL);
selectInnerLoop(pParse, p, -1, &sSort,
&sDistinct, pDest,
addrOutputRow+1, addrSetAbort);
sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
VdbeComment((v, "end groupby result generator"));
/* Generate a subroutine that will reset the group-by accumulator
*/
sqlite3VdbeResolveLabel(v, addrReset);
resetAccumulator(pParse, pAggInfo);
sqlite3VdbeAddOp2(v, OP_Integer, 0, iUseFlag);
VdbeComment((v, "indicate accumulator empty"));
sqlite3VdbeAddOp1(v, OP_Return, regReset);
if( distFlag!=0 && eDist!=WHERE_DISTINCT_NOOP ){
struct AggInfo_func *pF = &pAggInfo->aFunc[0];
fixDistinctOpenEph(pParse, eDist, pF->iDistinct, pF->iDistAddr);
}
} /* endif pGroupBy. Begin aggregate queries without GROUP BY: */
else {
Table *pTab;
if( (pTab = isSimpleCount(p, pAggInfo))!=0 ){
/* If isSimpleCount() returns a pointer to a Table structure, then
** the SQL statement is of the form:
**
** SELECT count(*) FROM <tbl>
**
** where the Table structure returned represents table <tbl>.
**
** This statement is so common that it is optimized specially. The
** OP_Count instruction is executed either on the intkey table that
** contains the data for table <tbl> or on one of its indexes. It
** is better to execute the op on an index, as indexes are almost
** always spread across less pages than their corresponding tables.
*/
const int iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
const int iCsr = pParse->nTab++; /* Cursor to scan b-tree */
Index *pIdx; /* Iterator variable */
KeyInfo *pKeyInfo = 0; /* Keyinfo for scanned index */
Index *pBest = 0; /* Best index found so far */
Pgno iRoot = pTab->tnum; /* Root page of scanned b-tree */
sqlite3CodeVerifySchema(pParse, iDb);
sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
/* Search for the index that has the lowest scan cost.
**
** (2011-04-15) Do not do a full scan of an unordered index.
**
** (2013-10-03) Do not count the entries in a partial index.
**
** In practice the KeyInfo structure will not be used. It is only
** passed to keep OP_OpenRead happy.
*/
if( !HasRowid(pTab) ) pBest = sqlite3PrimaryKeyIndex(pTab);
if( !p->pSrc->a[0].fg.notIndexed ){
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
if( pIdx->bUnordered==0
&& pIdx->szIdxRow<pTab->szTabRow
&& pIdx->pPartIdxWhere==0
&& (!pBest || pIdx->szIdxRow<pBest->szIdxRow)
){
pBest = pIdx;
}
}
}
if( pBest ){
iRoot = pBest->tnum;
pKeyInfo = sqlite3KeyInfoOfIndex(pParse, pBest);
}
/* Open a read-only cursor, execute the OP_Count, close the cursor. */
sqlite3VdbeAddOp4Int(v, OP_OpenRead, iCsr, (int)iRoot, iDb, 1);
if( pKeyInfo ){
sqlite3VdbeChangeP4(v, -1, (char *)pKeyInfo, P4_KEYINFO);
}
assignAggregateRegisters(pParse, pAggInfo);
sqlite3VdbeAddOp2(v, OP_Count, iCsr, AggInfoFuncReg(pAggInfo,0));
sqlite3VdbeAddOp1(v, OP_Close, iCsr);
explainSimpleCount(pParse, pTab, pBest);
}else{
int regAcc = 0; /* "populate accumulators" flag */
ExprList *pDistinct = 0;
u16 distFlag = 0;
int eDist;
/* If there are accumulator registers but no min() or max() functions
** without FILTER clauses, allocate register regAcc. Register regAcc
** will contain 0 the first time the inner loop runs, and 1 thereafter.
** The code generated by updateAccumulator() uses this to ensure
** that the accumulator registers are (a) updated only once if
** there are no min() or max functions or (b) always updated for the
** first row visited by the aggregate, so that they are updated at
** least once even if the FILTER clause means the min() or max()
** function visits zero rows. */
if( pAggInfo->nAccumulator ){
for(i=0; i<pAggInfo->nFunc; i++){
if( ExprHasProperty(pAggInfo->aFunc[i].pFExpr, EP_WinFunc) ){
continue;
}
if( pAggInfo->aFunc[i].pFunc->funcFlags&SQLITE_FUNC_NEEDCOLL ){
break;
}
}
if( i==pAggInfo->nFunc ){
regAcc = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Integer, 0, regAcc);
}
}else if( pAggInfo->nFunc==1 && pAggInfo->aFunc[0].iDistinct>=0 ){
assert( ExprUseXList(pAggInfo->aFunc[0].pFExpr) );
pDistinct = pAggInfo->aFunc[0].pFExpr->x.pList;
distFlag = pDistinct ? (WHERE_WANT_DISTINCT|WHERE_AGG_DISTINCT) : 0;
}
assignAggregateRegisters(pParse, pAggInfo);
/* This case runs if the aggregate has no GROUP BY clause. The
** processing is much simpler since there is only a single row
** of output.
*/
assert( p->pGroupBy==0 );
resetAccumulator(pParse, pAggInfo);
/* If this query is a candidate for the min/max optimization, then
** minMaxFlag will have been previously set to either
** WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX and pMinMaxOrderBy will
** be an appropriate ORDER BY expression for the optimization.
*/
assert( minMaxFlag==WHERE_ORDERBY_NORMAL || pMinMaxOrderBy!=0 );
assert( pMinMaxOrderBy==0 || pMinMaxOrderBy->nExpr==1 );
TREETRACE(0x2,pParse,p,("WhereBegin\n"));
pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pMinMaxOrderBy,
pDistinct, p, minMaxFlag|distFlag, 0);
if( pWInfo==0 ){
goto select_end;
}
TREETRACE(0x2,pParse,p,("WhereBegin returns\n"));
eDist = sqlite3WhereIsDistinct(pWInfo);
updateAccumulator(pParse, regAcc, pAggInfo, eDist);
if( eDist!=WHERE_DISTINCT_NOOP ){
struct AggInfo_func *pF = pAggInfo->aFunc;
if( pF ){
fixDistinctOpenEph(pParse, eDist, pF->iDistinct, pF->iDistAddr);
}
}
if( regAcc ) sqlite3VdbeAddOp2(v, OP_Integer, 1, regAcc);
if( minMaxFlag ){
sqlite3WhereMinMaxOptEarlyOut(v, pWInfo);
}
TREETRACE(0x2,pParse,p,("WhereEnd\n"));
sqlite3WhereEnd(pWInfo);
finalizeAggFunctions(pParse, pAggInfo);
}
sSort.pOrderBy = 0;
sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL);
selectInnerLoop(pParse, p, -1, 0, 0,
pDest, addrEnd, addrEnd);
}
sqlite3VdbeResolveLabel(v, addrEnd);
} /* endif aggregate query */
if( sDistinct.eTnctType==WHERE_DISTINCT_UNORDERED ){
explainTempTable(pParse, "DISTINCT");
}
/* If there is an ORDER BY clause, then we need to sort the results
** and send them to the callback one by one.
*/
if( sSort.pOrderBy ){
assert( p->pEList==pEList );
generateSortTail(pParse, p, &sSort, pEList->nExpr, pDest);
}
/* Jump here to skip this query
*/
sqlite3VdbeResolveLabel(v, iEnd);
/* The SELECT has been coded. If there is an error in the Parse structure,
** set the return code to 1. Otherwise 0. */
rc = (pParse->nErr>0);
/* Control jumps to here if an error is encountered above, or upon
** successful coding of the SELECT.
*/
select_end:
assert( db->mallocFailed==0 || db->mallocFailed==1 );
assert( db->mallocFailed==0 || pParse->nErr!=0 );
sqlite3ExprListDelete(db, pMinMaxOrderBy);
#ifdef SQLITE_DEBUG
if( pAggInfo && !db->mallocFailed ){
for(i=0; i<pAggInfo->nColumn; i++){
Expr *pExpr = pAggInfo->aCol[i].pCExpr;
if( pExpr==0 ) continue;
assert( pExpr->pAggInfo==pAggInfo );
assert( pExpr->iAgg==i );
}
for(i=0; i<pAggInfo->nFunc; i++){
Expr *pExpr = pAggInfo->aFunc[i].pFExpr;
assert( pExpr!=0 );
assert( pExpr->pAggInfo==pAggInfo );
assert( pExpr->iAgg==i );
}
}
#endif
#if TREETRACE_ENABLED
TREETRACE(0x1,pParse,p,("end processing\n"));
if( (sqlite3TreeTrace & 0x40000)!=0 && ExplainQueryPlanParent(pParse)==0 ){
sqlite3TreeViewSelect(0, p, 0);
}
#endif
ExplainQueryPlanPop(pParse);
return rc;
}