blob: 963f0db29f125a4de828e734e433ed1b5275e801 [file] [log] [blame]
drh75897232000-05-29 14:26:00 +00001/*
drhb19a2bc2001-09-16 00:13:26 +00002** 2001 September 15
drh75897232000-05-29 14:26:00 +00003**
drhb19a2bc2001-09-16 00:13:26 +00004** The author disclaims copyright to this source code. In place of
5** a legal notice, here is a blessing:
drh75897232000-05-29 14:26:00 +00006**
drhb19a2bc2001-09-16 00:13:26 +00007** May you do good and not evil.
8** May you find forgiveness for yourself and forgive others.
9** May you share freely, never taking more than you give.
drh75897232000-05-29 14:26:00 +000010**
11*************************************************************************
12** This module contains C code that generates VDBE code used to process
drh51669862004-12-18 18:40:26 +000013** the WHERE clause of SQL statements. This module is reponsible for
14** generating the code that loops through a table looking for applicable
15** rows. Indices are selected and used to speed the search when doing
16** so is applicable. Because this module is responsible for selecting
17** indices, you might also think of this module as the "query optimizer".
drh75897232000-05-29 14:26:00 +000018**
danielk197765fd59f2006-06-24 11:51:33 +000019** $Id: where.c,v 1.223 2006/06/24 11:51:35 danielk1977 Exp $
drh75897232000-05-29 14:26:00 +000020*/
21#include "sqliteInt.h"
22
23/*
drh0aa74ed2005-07-16 13:33:20 +000024** The number of bits in a Bitmask. "BMS" means "BitMask Size".
25*/
drh29dda4a2005-07-21 18:23:20 +000026#define BMS (sizeof(Bitmask)*8)
drh0aa74ed2005-07-16 13:33:20 +000027
28/*
29** Determine the number of elements in an array.
30*/
31#define ARRAYSIZE(X) (sizeof(X)/sizeof(X[0]))
32
drh51147ba2005-07-23 22:59:55 +000033/*
34** Trace output macros
35*/
36#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
37int sqlite3_where_trace = 0;
38# define TRACE(X) if(sqlite3_where_trace) sqlite3DebugPrintf X
39#else
40# define TRACE(X)
41#endif
42
drh0fcef5e2005-07-19 17:38:22 +000043/* Forward reference
44*/
45typedef struct WhereClause WhereClause;
drh0aa74ed2005-07-16 13:33:20 +000046
47/*
drh75897232000-05-29 14:26:00 +000048** The query generator uses an array of instances of this structure to
49** help it analyze the subexpressions of the WHERE clause. Each WHERE
50** clause subexpression is separated from the others by an AND operator.
drh51669862004-12-18 18:40:26 +000051**
drh0fcef5e2005-07-19 17:38:22 +000052** All WhereTerms are collected into a single WhereClause structure.
53** The following identity holds:
drh51669862004-12-18 18:40:26 +000054**
drh0fcef5e2005-07-19 17:38:22 +000055** WhereTerm.pWC->a[WhereTerm.idx] == WhereTerm
drh51669862004-12-18 18:40:26 +000056**
drh0fcef5e2005-07-19 17:38:22 +000057** When a term is of the form:
58**
59** X <op> <expr>
60**
61** where X is a column name and <op> is one of certain operators,
62** then WhereTerm.leftCursor and WhereTerm.leftColumn record the
drh51147ba2005-07-23 22:59:55 +000063** cursor number and column number for X. WhereTerm.operator records
64** the <op> using a bitmask encoding defined by WO_xxx below. The
65** use of a bitmask encoding for the operator allows us to search
66** quickly for terms that match any of several different operators.
drh0fcef5e2005-07-19 17:38:22 +000067**
68** prereqRight and prereqAll record sets of cursor numbers,
drh51669862004-12-18 18:40:26 +000069** but they do so indirectly. A single ExprMaskSet structure translates
70** cursor number into bits and the translated bit is stored in the prereq
71** fields. The translation is used in order to maximize the number of
72** bits that will fit in a Bitmask. The VDBE cursor numbers might be
73** spread out over the non-negative integers. For example, the cursor
74** numbers might be 3, 8, 9, 10, 20, 23, 41, and 45. The ExprMaskSet
75** translates these sparse cursor numbers into consecutive integers
76** beginning with 0 in order to make the best possible use of the available
77** bits in the Bitmask. So, in the example above, the cursor numbers
78** would be mapped into integers 0 through 7.
drh75897232000-05-29 14:26:00 +000079*/
drh0aa74ed2005-07-16 13:33:20 +000080typedef struct WhereTerm WhereTerm;
81struct WhereTerm {
drh0fcef5e2005-07-19 17:38:22 +000082 Expr *pExpr; /* Pointer to the subexpression */
drh45b1ee42005-08-02 17:48:22 +000083 i16 iParent; /* Disable pWC->a[iParent] when this term disabled */
drh0fcef5e2005-07-19 17:38:22 +000084 i16 leftCursor; /* Cursor number of X in "X <op> <expr>" */
85 i16 leftColumn; /* Column number of X in "X <op> <expr>" */
drhb52076c2006-01-23 13:22:09 +000086 u16 eOperator; /* A WO_xx value describing <op> */
drh6c30be82005-07-29 15:10:17 +000087 u8 flags; /* Bit flags. See below */
drh45b1ee42005-08-02 17:48:22 +000088 u8 nChild; /* Number of children that must disable us */
drh0fcef5e2005-07-19 17:38:22 +000089 WhereClause *pWC; /* The clause this term is part of */
90 Bitmask prereqRight; /* Bitmask of tables used by pRight */
drh51669862004-12-18 18:40:26 +000091 Bitmask prereqAll; /* Bitmask of tables referenced by p */
drh75897232000-05-29 14:26:00 +000092};
93
94/*
drh0aa74ed2005-07-16 13:33:20 +000095** Allowed values of WhereTerm.flags
96*/
drh6c30be82005-07-29 15:10:17 +000097#define TERM_DYNAMIC 0x01 /* Need to call sqlite3ExprDelete(pExpr) */
98#define TERM_VIRTUAL 0x02 /* Added by the optimizer. Do not code */
99#define TERM_CODED 0x04 /* This term is already coded */
drh45b1ee42005-08-02 17:48:22 +0000100#define TERM_COPIED 0x08 /* Has a child */
drh6c30be82005-07-29 15:10:17 +0000101#define TERM_OR_OK 0x10 /* Used during OR-clause processing */
drh0aa74ed2005-07-16 13:33:20 +0000102
103/*
104** An instance of the following structure holds all information about a
105** WHERE clause. Mostly this is a container for one or more WhereTerms.
106*/
drh0aa74ed2005-07-16 13:33:20 +0000107struct WhereClause {
drhfe05af82005-07-21 03:14:59 +0000108 Parse *pParse; /* The parser context */
drh0aa74ed2005-07-16 13:33:20 +0000109 int nTerm; /* Number of terms */
110 int nSlot; /* Number of entries in a[] */
drh51147ba2005-07-23 22:59:55 +0000111 WhereTerm *a; /* Each a[] describes a term of the WHERE cluase */
112 WhereTerm aStatic[10]; /* Initial static space for a[] */
drhe23399f2005-07-22 00:31:39 +0000113};
114
115/*
drh6a3ea0e2003-05-02 14:32:12 +0000116** An instance of the following structure keeps track of a mapping
drh0aa74ed2005-07-16 13:33:20 +0000117** between VDBE cursor numbers and bits of the bitmasks in WhereTerm.
drh51669862004-12-18 18:40:26 +0000118**
119** The VDBE cursor numbers are small integers contained in
120** SrcList_item.iCursor and Expr.iTable fields. For any given WHERE
121** clause, the cursor numbers might not begin with 0 and they might
122** contain gaps in the numbering sequence. But we want to make maximum
123** use of the bits in our bitmasks. This structure provides a mapping
124** from the sparse cursor numbers into consecutive integers beginning
125** with 0.
126**
127** If ExprMaskSet.ix[A]==B it means that The A-th bit of a Bitmask
128** corresponds VDBE cursor number B. The A-th bit of a bitmask is 1<<A.
129**
130** For example, if the WHERE clause expression used these VDBE
131** cursors: 4, 5, 8, 29, 57, 73. Then the ExprMaskSet structure
132** would map those cursor numbers into bits 0 through 5.
133**
134** Note that the mapping is not necessarily ordered. In the example
135** above, the mapping might go like this: 4->3, 5->1, 8->2, 29->0,
136** 57->5, 73->4. Or one of 719 other combinations might be used. It
137** does not really matter. What is important is that sparse cursor
138** numbers all get mapped into bit numbers that begin with 0 and contain
139** no gaps.
drh6a3ea0e2003-05-02 14:32:12 +0000140*/
141typedef struct ExprMaskSet ExprMaskSet;
142struct ExprMaskSet {
drh1398ad32005-01-19 23:24:50 +0000143 int n; /* Number of assigned cursor values */
144 int ix[sizeof(Bitmask)*8]; /* Cursor assigned to each bit */
drh6a3ea0e2003-05-02 14:32:12 +0000145};
146
drh0aa74ed2005-07-16 13:33:20 +0000147
drh6a3ea0e2003-05-02 14:32:12 +0000148/*
drh51147ba2005-07-23 22:59:55 +0000149** Bitmasks for the operators that indices are able to exploit. An
150** OR-ed combination of these values can be used when searching for
151** terms in the where clause.
152*/
153#define WO_IN 1
drha6110402005-07-28 20:51:19 +0000154#define WO_EQ 2
drh51147ba2005-07-23 22:59:55 +0000155#define WO_LT (WO_EQ<<(TK_LT-TK_EQ))
156#define WO_LE (WO_EQ<<(TK_LE-TK_EQ))
157#define WO_GT (WO_EQ<<(TK_GT-TK_EQ))
158#define WO_GE (WO_EQ<<(TK_GE-TK_EQ))
drh7f375902006-06-13 17:38:59 +0000159#define WO_MATCH 64
drh51147ba2005-07-23 22:59:55 +0000160
161/*
162** Value for flags returned by bestIndex()
163*/
164#define WHERE_ROWID_EQ 0x0001 /* rowid=EXPR or rowid IN (...) */
165#define WHERE_ROWID_RANGE 0x0002 /* rowid<EXPR and/or rowid>EXPR */
166#define WHERE_COLUMN_EQ 0x0010 /* x=EXPR or x IN (...) */
167#define WHERE_COLUMN_RANGE 0x0020 /* x<EXPR and/or x>EXPR */
168#define WHERE_COLUMN_IN 0x0040 /* x IN (...) */
169#define WHERE_TOP_LIMIT 0x0100 /* x<EXPR or x<=EXPR constraint */
170#define WHERE_BTM_LIMIT 0x0200 /* x>EXPR or x>=EXPR constraint */
171#define WHERE_IDX_ONLY 0x0800 /* Use index only - omit table */
172#define WHERE_ORDERBY 0x1000 /* Output will appear in correct order */
173#define WHERE_REVERSE 0x2000 /* Scan in reverse order */
drh943af3c2005-07-29 19:43:58 +0000174#define WHERE_UNIQUE 0x4000 /* Selects no more than one row */
drh9eff6162006-06-12 21:59:13 +0000175#define WHERE_VIRTUALTABLE 0x8000 /* Use virtual-table processing */
drh51147ba2005-07-23 22:59:55 +0000176
177/*
drh0aa74ed2005-07-16 13:33:20 +0000178** Initialize a preallocated WhereClause structure.
drh75897232000-05-29 14:26:00 +0000179*/
drhfe05af82005-07-21 03:14:59 +0000180static void whereClauseInit(WhereClause *pWC, Parse *pParse){
181 pWC->pParse = pParse;
drh0aa74ed2005-07-16 13:33:20 +0000182 pWC->nTerm = 0;
183 pWC->nSlot = ARRAYSIZE(pWC->aStatic);
184 pWC->a = pWC->aStatic;
185}
186
187/*
188** Deallocate a WhereClause structure. The WhereClause structure
189** itself is not freed. This routine is the inverse of whereClauseInit().
190*/
191static void whereClauseClear(WhereClause *pWC){
192 int i;
193 WhereTerm *a;
194 for(i=pWC->nTerm-1, a=pWC->a; i>=0; i--, a++){
195 if( a->flags & TERM_DYNAMIC ){
drh0fcef5e2005-07-19 17:38:22 +0000196 sqlite3ExprDelete(a->pExpr);
drh0aa74ed2005-07-16 13:33:20 +0000197 }
198 }
199 if( pWC->a!=pWC->aStatic ){
200 sqliteFree(pWC->a);
201 }
202}
203
204/*
205** Add a new entries to the WhereClause structure. Increase the allocated
206** space as necessary.
drh9eb20282005-08-24 03:52:18 +0000207**
208** WARNING: This routine might reallocate the space used to store
209** WhereTerms. All pointers to WhereTerms should be invalided after
210** calling this routine. Such pointers may be reinitialized by referencing
211** the pWC->a[] array.
drh0aa74ed2005-07-16 13:33:20 +0000212*/
drh9eb20282005-08-24 03:52:18 +0000213static int whereClauseInsert(WhereClause *pWC, Expr *p, int flags){
drh0aa74ed2005-07-16 13:33:20 +0000214 WhereTerm *pTerm;
drh9eb20282005-08-24 03:52:18 +0000215 int idx;
drh0aa74ed2005-07-16 13:33:20 +0000216 if( pWC->nTerm>=pWC->nSlot ){
217 WhereTerm *pOld = pWC->a;
218 pWC->a = sqliteMalloc( sizeof(pWC->a[0])*pWC->nSlot*2 );
drh0fcef5e2005-07-19 17:38:22 +0000219 if( pWC->a==0 ) return 0;
drh0aa74ed2005-07-16 13:33:20 +0000220 memcpy(pWC->a, pOld, sizeof(pWC->a[0])*pWC->nTerm);
221 if( pOld!=pWC->aStatic ){
222 sqliteFree(pOld);
223 }
224 pWC->nSlot *= 2;
225 }
drh9eb20282005-08-24 03:52:18 +0000226 pTerm = &pWC->a[idx = pWC->nTerm];
drh0fcef5e2005-07-19 17:38:22 +0000227 pWC->nTerm++;
228 pTerm->pExpr = p;
drh0aa74ed2005-07-16 13:33:20 +0000229 pTerm->flags = flags;
drh0fcef5e2005-07-19 17:38:22 +0000230 pTerm->pWC = pWC;
drh45b1ee42005-08-02 17:48:22 +0000231 pTerm->iParent = -1;
drh9eb20282005-08-24 03:52:18 +0000232 return idx;
drh0aa74ed2005-07-16 13:33:20 +0000233}
drh75897232000-05-29 14:26:00 +0000234
235/*
drh51669862004-12-18 18:40:26 +0000236** This routine identifies subexpressions in the WHERE clause where
drhb6fb62d2005-09-20 08:47:20 +0000237** each subexpression is separated by the AND operator or some other
drh6c30be82005-07-29 15:10:17 +0000238** operator specified in the op parameter. The WhereClause structure
239** is filled with pointers to subexpressions. For example:
drh75897232000-05-29 14:26:00 +0000240**
drh51669862004-12-18 18:40:26 +0000241** WHERE a=='hello' AND coalesce(b,11)<10 AND (c+12!=d OR c==22)
242** \________/ \_______________/ \________________/
243** slot[0] slot[1] slot[2]
244**
245** The original WHERE clause in pExpr is unaltered. All this routine
drh51147ba2005-07-23 22:59:55 +0000246** does is make slot[] entries point to substructure within pExpr.
drh51669862004-12-18 18:40:26 +0000247**
drh51147ba2005-07-23 22:59:55 +0000248** In the previous sentence and in the diagram, "slot[]" refers to
249** the WhereClause.a[] array. This array grows as needed to contain
250** all terms of the WHERE clause.
drh75897232000-05-29 14:26:00 +0000251*/
drh6c30be82005-07-29 15:10:17 +0000252static void whereSplit(WhereClause *pWC, Expr *pExpr, int op){
drh0aa74ed2005-07-16 13:33:20 +0000253 if( pExpr==0 ) return;
drh6c30be82005-07-29 15:10:17 +0000254 if( pExpr->op!=op ){
drh0aa74ed2005-07-16 13:33:20 +0000255 whereClauseInsert(pWC, pExpr, 0);
drh75897232000-05-29 14:26:00 +0000256 }else{
drh6c30be82005-07-29 15:10:17 +0000257 whereSplit(pWC, pExpr->pLeft, op);
258 whereSplit(pWC, pExpr->pRight, op);
drh75897232000-05-29 14:26:00 +0000259 }
drh75897232000-05-29 14:26:00 +0000260}
261
262/*
drh6a3ea0e2003-05-02 14:32:12 +0000263** Initialize an expression mask set
264*/
265#define initMaskSet(P) memset(P, 0, sizeof(*P))
266
267/*
drh1398ad32005-01-19 23:24:50 +0000268** Return the bitmask for the given cursor number. Return 0 if
269** iCursor is not in the set.
drh6a3ea0e2003-05-02 14:32:12 +0000270*/
drh51669862004-12-18 18:40:26 +0000271static Bitmask getMask(ExprMaskSet *pMaskSet, int iCursor){
drh6a3ea0e2003-05-02 14:32:12 +0000272 int i;
273 for(i=0; i<pMaskSet->n; i++){
drh51669862004-12-18 18:40:26 +0000274 if( pMaskSet->ix[i]==iCursor ){
275 return ((Bitmask)1)<<i;
276 }
drh6a3ea0e2003-05-02 14:32:12 +0000277 }
drh6a3ea0e2003-05-02 14:32:12 +0000278 return 0;
279}
280
281/*
drh1398ad32005-01-19 23:24:50 +0000282** Create a new mask for cursor iCursor.
drh0fcef5e2005-07-19 17:38:22 +0000283**
284** There is one cursor per table in the FROM clause. The number of
285** tables in the FROM clause is limited by a test early in the
drhb6fb62d2005-09-20 08:47:20 +0000286** sqlite3WhereBegin() routine. So we know that the pMaskSet->ix[]
drh0fcef5e2005-07-19 17:38:22 +0000287** array will never overflow.
drh1398ad32005-01-19 23:24:50 +0000288*/
289static void createMask(ExprMaskSet *pMaskSet, int iCursor){
drh0fcef5e2005-07-19 17:38:22 +0000290 assert( pMaskSet->n < ARRAYSIZE(pMaskSet->ix) );
291 pMaskSet->ix[pMaskSet->n++] = iCursor;
drh1398ad32005-01-19 23:24:50 +0000292}
293
294/*
drh75897232000-05-29 14:26:00 +0000295** This routine walks (recursively) an expression tree and generates
296** a bitmask indicating which tables are used in that expression
drh6a3ea0e2003-05-02 14:32:12 +0000297** tree.
drh75897232000-05-29 14:26:00 +0000298**
299** In order for this routine to work, the calling function must have
drh626a8792005-01-17 22:08:19 +0000300** previously invoked sqlite3ExprResolveNames() on the expression. See
drh75897232000-05-29 14:26:00 +0000301** the header comment on that routine for additional information.
drh626a8792005-01-17 22:08:19 +0000302** The sqlite3ExprResolveNames() routines looks for column names and
drh6a3ea0e2003-05-02 14:32:12 +0000303** sets their opcodes to TK_COLUMN and their Expr.iTable fields to
drh51147ba2005-07-23 22:59:55 +0000304** the VDBE cursor number of the table. This routine just has to
305** translate the cursor numbers into bitmask values and OR all
306** the bitmasks together.
drh75897232000-05-29 14:26:00 +0000307*/
drhf5b11382005-09-17 13:07:13 +0000308static Bitmask exprListTableUsage(ExprMaskSet*, ExprList*);
309static Bitmask exprSelectTableUsage(ExprMaskSet*, Select*);
drh51669862004-12-18 18:40:26 +0000310static Bitmask exprTableUsage(ExprMaskSet *pMaskSet, Expr *p){
311 Bitmask mask = 0;
drh75897232000-05-29 14:26:00 +0000312 if( p==0 ) return 0;
drh967e8b72000-06-21 13:59:10 +0000313 if( p->op==TK_COLUMN ){
drh8feb4b12004-07-19 02:12:14 +0000314 mask = getMask(pMaskSet, p->iTable);
drh8feb4b12004-07-19 02:12:14 +0000315 return mask;
drh75897232000-05-29 14:26:00 +0000316 }
danielk1977b3bce662005-01-29 08:32:43 +0000317 mask = exprTableUsage(pMaskSet, p->pRight);
318 mask |= exprTableUsage(pMaskSet, p->pLeft);
319 mask |= exprListTableUsage(pMaskSet, p->pList);
drhf5b11382005-09-17 13:07:13 +0000320 mask |= exprSelectTableUsage(pMaskSet, p->pSelect);
danielk1977b3bce662005-01-29 08:32:43 +0000321 return mask;
322}
323static Bitmask exprListTableUsage(ExprMaskSet *pMaskSet, ExprList *pList){
324 int i;
325 Bitmask mask = 0;
326 if( pList ){
327 for(i=0; i<pList->nExpr; i++){
328 mask |= exprTableUsage(pMaskSet, pList->a[i].pExpr);
drhdd579122002-04-02 01:58:57 +0000329 }
330 }
drh75897232000-05-29 14:26:00 +0000331 return mask;
332}
drhf5b11382005-09-17 13:07:13 +0000333static Bitmask exprSelectTableUsage(ExprMaskSet *pMaskSet, Select *pS){
334 Bitmask mask;
335 if( pS==0 ){
336 mask = 0;
337 }else{
338 mask = exprListTableUsage(pMaskSet, pS->pEList);
339 mask |= exprListTableUsage(pMaskSet, pS->pGroupBy);
340 mask |= exprListTableUsage(pMaskSet, pS->pOrderBy);
341 mask |= exprTableUsage(pMaskSet, pS->pWhere);
342 mask |= exprTableUsage(pMaskSet, pS->pHaving);
343 }
344 return mask;
345}
drh75897232000-05-29 14:26:00 +0000346
347/*
drh487ab3c2001-11-08 00:45:21 +0000348** Return TRUE if the given operator is one of the operators that is
drh51669862004-12-18 18:40:26 +0000349** allowed for an indexable WHERE clause term. The allowed operators are
drhc27a1ce2002-06-14 20:58:45 +0000350** "=", "<", ">", "<=", ">=", and "IN".
drh487ab3c2001-11-08 00:45:21 +0000351*/
352static int allowedOp(int op){
drhfe05af82005-07-21 03:14:59 +0000353 assert( TK_GT>TK_EQ && TK_GT<TK_GE );
354 assert( TK_LT>TK_EQ && TK_LT<TK_GE );
355 assert( TK_LE>TK_EQ && TK_LE<TK_GE );
356 assert( TK_GE==TK_EQ+4 );
drh9a432672004-10-04 13:38:09 +0000357 return op==TK_IN || (op>=TK_EQ && op<=TK_GE);
drh487ab3c2001-11-08 00:45:21 +0000358}
359
360/*
drh51669862004-12-18 18:40:26 +0000361** Swap two objects of type T.
drh193bd772004-07-20 18:23:14 +0000362*/
363#define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;}
364
365/*
drh0fcef5e2005-07-19 17:38:22 +0000366** Commute a comparision operator. Expressions of the form "X op Y"
367** are converted into "Y op X".
drh193bd772004-07-20 18:23:14 +0000368*/
drh0fcef5e2005-07-19 17:38:22 +0000369static void exprCommute(Expr *pExpr){
drhfe05af82005-07-21 03:14:59 +0000370 assert( allowedOp(pExpr->op) && pExpr->op!=TK_IN );
drh0fcef5e2005-07-19 17:38:22 +0000371 SWAP(CollSeq*,pExpr->pRight->pColl,pExpr->pLeft->pColl);
372 SWAP(Expr*,pExpr->pRight,pExpr->pLeft);
373 if( pExpr->op>=TK_GT ){
374 assert( TK_LT==TK_GT+2 );
375 assert( TK_GE==TK_LE+2 );
376 assert( TK_GT>TK_EQ );
377 assert( TK_GT<TK_LE );
378 assert( pExpr->op>=TK_GT && pExpr->op<=TK_GE );
379 pExpr->op = ((pExpr->op-TK_GT)^2)+TK_GT;
drh193bd772004-07-20 18:23:14 +0000380 }
drh193bd772004-07-20 18:23:14 +0000381}
382
383/*
drhfe05af82005-07-21 03:14:59 +0000384** Translate from TK_xx operator to WO_xx bitmask.
385*/
386static int operatorMask(int op){
drh51147ba2005-07-23 22:59:55 +0000387 int c;
drhfe05af82005-07-21 03:14:59 +0000388 assert( allowedOp(op) );
389 if( op==TK_IN ){
drh51147ba2005-07-23 22:59:55 +0000390 c = WO_IN;
drhfe05af82005-07-21 03:14:59 +0000391 }else{
drh51147ba2005-07-23 22:59:55 +0000392 c = WO_EQ<<(op-TK_EQ);
drhfe05af82005-07-21 03:14:59 +0000393 }
drh51147ba2005-07-23 22:59:55 +0000394 assert( op!=TK_IN || c==WO_IN );
395 assert( op!=TK_EQ || c==WO_EQ );
396 assert( op!=TK_LT || c==WO_LT );
397 assert( op!=TK_LE || c==WO_LE );
398 assert( op!=TK_GT || c==WO_GT );
399 assert( op!=TK_GE || c==WO_GE );
400 return c;
drhfe05af82005-07-21 03:14:59 +0000401}
402
403/*
404** Search for a term in the WHERE clause that is of the form "X <op> <expr>"
405** where X is a reference to the iColumn of table iCur and <op> is one of
406** the WO_xx operator codes specified by the op parameter.
407** Return a pointer to the term. Return 0 if not found.
408*/
409static WhereTerm *findTerm(
410 WhereClause *pWC, /* The WHERE clause to be searched */
411 int iCur, /* Cursor number of LHS */
412 int iColumn, /* Column number of LHS */
413 Bitmask notReady, /* RHS must not overlap with this mask */
drh51147ba2005-07-23 22:59:55 +0000414 u16 op, /* Mask of WO_xx values describing operator */
drhfe05af82005-07-21 03:14:59 +0000415 Index *pIdx /* Must be compatible with this index, if not NULL */
416){
417 WhereTerm *pTerm;
418 int k;
419 for(pTerm=pWC->a, k=pWC->nTerm; k; k--, pTerm++){
420 if( pTerm->leftCursor==iCur
421 && (pTerm->prereqRight & notReady)==0
422 && pTerm->leftColumn==iColumn
drhb52076c2006-01-23 13:22:09 +0000423 && (pTerm->eOperator & op)!=0
drhfe05af82005-07-21 03:14:59 +0000424 ){
425 if( iCur>=0 && pIdx ){
426 Expr *pX = pTerm->pExpr;
427 CollSeq *pColl;
428 char idxaff;
danielk1977f0113002006-01-24 12:09:17 +0000429 int j;
drhfe05af82005-07-21 03:14:59 +0000430 Parse *pParse = pWC->pParse;
431
432 idxaff = pIdx->pTable->aCol[iColumn].affinity;
433 if( !sqlite3IndexAffinityOk(pX, idxaff) ) continue;
434 pColl = sqlite3ExprCollSeq(pParse, pX->pLeft);
435 if( !pColl ){
436 if( pX->pRight ){
437 pColl = sqlite3ExprCollSeq(pParse, pX->pRight);
438 }
439 if( !pColl ){
440 pColl = pParse->db->pDfltColl;
441 }
442 }
danielk1977f0113002006-01-24 12:09:17 +0000443 for(j=0; j<pIdx->nColumn && pIdx->aiColumn[j]!=iColumn; j++){}
444 assert( j<pIdx->nColumn );
445 if( sqlite3StrICmp(pColl->zName, pIdx->azColl[j]) ) continue;
drhfe05af82005-07-21 03:14:59 +0000446 }
447 return pTerm;
448 }
449 }
450 return 0;
451}
452
drh6c30be82005-07-29 15:10:17 +0000453/* Forward reference */
drh9eb20282005-08-24 03:52:18 +0000454static void exprAnalyze(SrcList*, ExprMaskSet*, WhereClause*, int);
drh6c30be82005-07-29 15:10:17 +0000455
456/*
457** Call exprAnalyze on all terms in a WHERE clause.
458**
459**
460*/
461static void exprAnalyzeAll(
462 SrcList *pTabList, /* the FROM clause */
463 ExprMaskSet *pMaskSet, /* table masks */
464 WhereClause *pWC /* the WHERE clause to be analyzed */
465){
drh6c30be82005-07-29 15:10:17 +0000466 int i;
drh9eb20282005-08-24 03:52:18 +0000467 for(i=pWC->nTerm-1; i>=0; i--){
468 exprAnalyze(pTabList, pMaskSet, pWC, i);
drh6c30be82005-07-29 15:10:17 +0000469 }
470}
471
drhd2687b72005-08-12 22:56:09 +0000472#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
473/*
474** Check to see if the given expression is a LIKE or GLOB operator that
475** can be optimized using inequality constraints. Return TRUE if it is
476** so and false if not.
477**
478** In order for the operator to be optimizible, the RHS must be a string
479** literal that does not begin with a wildcard.
480*/
481static int isLikeOrGlob(
drh55ef4d92005-08-14 01:20:37 +0000482 sqlite3 *db, /* The database */
drhd2687b72005-08-12 22:56:09 +0000483 Expr *pExpr, /* Test this expression */
484 int *pnPattern, /* Number of non-wildcard prefix characters */
485 int *pisComplete /* True if the only wildcard is % in the last character */
486){
487 const char *z;
488 Expr *pRight, *pLeft;
drh55ef4d92005-08-14 01:20:37 +0000489 ExprList *pList;
drhd2687b72005-08-12 22:56:09 +0000490 int c, cnt;
drhd64fe2f2005-08-28 17:00:23 +0000491 int noCase;
drh55ef4d92005-08-14 01:20:37 +0000492 char wc[3];
drhd64fe2f2005-08-28 17:00:23 +0000493 CollSeq *pColl;
494
495 if( !sqlite3IsLikeFunction(db, pExpr, &noCase, wc) ){
drhd2687b72005-08-12 22:56:09 +0000496 return 0;
497 }
drh55ef4d92005-08-14 01:20:37 +0000498 pList = pExpr->pList;
499 pRight = pList->a[0].pExpr;
drhd2687b72005-08-12 22:56:09 +0000500 if( pRight->op!=TK_STRING ){
501 return 0;
502 }
drh55ef4d92005-08-14 01:20:37 +0000503 pLeft = pList->a[1].pExpr;
drhd2687b72005-08-12 22:56:09 +0000504 if( pLeft->op!=TK_COLUMN ){
505 return 0;
506 }
drhd64fe2f2005-08-28 17:00:23 +0000507 pColl = pLeft->pColl;
508 if( pColl==0 ){
509 pColl = db->pDfltColl;
510 }
511 if( (pColl->type!=SQLITE_COLL_BINARY || noCase) &&
512 (pColl->type!=SQLITE_COLL_NOCASE || !noCase) ){
513 return 0;
514 }
drhd2687b72005-08-12 22:56:09 +0000515 sqlite3DequoteExpr(pRight);
danielk197700fd9572005-12-07 06:27:43 +0000516 z = (char *)pRight->token.z;
drh55ef4d92005-08-14 01:20:37 +0000517 for(cnt=0; (c=z[cnt])!=0 && c!=wc[0] && c!=wc[1] && c!=wc[2]; cnt++){}
drhd2687b72005-08-12 22:56:09 +0000518 if( cnt==0 || 255==(u8)z[cnt] ){
519 return 0;
520 }
drh55ef4d92005-08-14 01:20:37 +0000521 *pisComplete = z[cnt]==wc[0] && z[cnt+1]==0;
drhd2687b72005-08-12 22:56:09 +0000522 *pnPattern = cnt;
523 return 1;
524}
525#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
526
drhfe05af82005-07-21 03:14:59 +0000527/*
drh7f375902006-06-13 17:38:59 +0000528** Check to see if the given expression is of the form
529**
530** column MATCH expr
531**
532** If it is then return TRUE. If not, return FALSE.
533*/
534static int isMatchOfColumn(
535 Expr *pExpr /* Test this expression */
536){
537 ExprList *pList;
538
539 if( pExpr->op!=TK_FUNCTION ){
540 return 0;
541 }
542 if( pExpr->token.n!=5 || sqlite3StrNICmp(pExpr->token.z,"match",5)!=0 ){
543 return 0;
544 }
545 pList = pExpr->pList;
546 if( pList->nExpr!=2 ){
547 return 0;
548 }
549 if( pList->a[1].pExpr->op != TK_COLUMN ){
550 return 0;
551 }
552 return 1;
553}
554
555/*
drh54a167d2005-11-26 14:08:07 +0000556** If the pBase expression originated in the ON or USING clause of
557** a join, then transfer the appropriate markings over to derived.
558*/
559static void transferJoinMarkings(Expr *pDerived, Expr *pBase){
560 pDerived->flags |= pBase->flags & EP_FromJoin;
561 pDerived->iRightJoinTable = pBase->iRightJoinTable;
562}
563
564
565/*
drh0aa74ed2005-07-16 13:33:20 +0000566** The input to this routine is an WhereTerm structure with only the
drh51147ba2005-07-23 22:59:55 +0000567** "pExpr" field filled in. The job of this routine is to analyze the
drh0aa74ed2005-07-16 13:33:20 +0000568** subexpression and populate all the other fields of the WhereTerm
drh75897232000-05-29 14:26:00 +0000569** structure.
drh51147ba2005-07-23 22:59:55 +0000570**
571** If the expression is of the form "<expr> <op> X" it gets commuted
572** to the standard form of "X <op> <expr>". If the expression is of
573** the form "X <op> Y" where both X and Y are columns, then the original
574** expression is unchanged and a new virtual expression of the form
drhb6fb62d2005-09-20 08:47:20 +0000575** "Y <op> X" is added to the WHERE clause and analyzed separately.
drh75897232000-05-29 14:26:00 +0000576*/
drh0fcef5e2005-07-19 17:38:22 +0000577static void exprAnalyze(
578 SrcList *pSrc, /* the FROM clause */
579 ExprMaskSet *pMaskSet, /* table masks */
drh9eb20282005-08-24 03:52:18 +0000580 WhereClause *pWC, /* the WHERE clause */
581 int idxTerm /* Index of the term to be analyzed */
drh0fcef5e2005-07-19 17:38:22 +0000582){
drh9eb20282005-08-24 03:52:18 +0000583 WhereTerm *pTerm = &pWC->a[idxTerm];
drh0fcef5e2005-07-19 17:38:22 +0000584 Expr *pExpr = pTerm->pExpr;
585 Bitmask prereqLeft;
586 Bitmask prereqAll;
drhd2687b72005-08-12 22:56:09 +0000587 int nPattern;
588 int isComplete;
drh0fcef5e2005-07-19 17:38:22 +0000589
danielk19779e128002006-01-18 16:51:35 +0000590 if( sqlite3MallocFailed() ) return;
drh0fcef5e2005-07-19 17:38:22 +0000591 prereqLeft = exprTableUsage(pMaskSet, pExpr->pLeft);
drhf5b11382005-09-17 13:07:13 +0000592 if( pExpr->op==TK_IN ){
593 assert( pExpr->pRight==0 );
594 pTerm->prereqRight = exprListTableUsage(pMaskSet, pExpr->pList)
595 | exprSelectTableUsage(pMaskSet, pExpr->pSelect);
596 }else{
597 pTerm->prereqRight = exprTableUsage(pMaskSet, pExpr->pRight);
598 }
drh22d6a532005-09-19 21:05:48 +0000599 prereqAll = exprTableUsage(pMaskSet, pExpr);
600 if( ExprHasProperty(pExpr, EP_FromJoin) ){
601 prereqAll |= getMask(pMaskSet, pExpr->iRightJoinTable);
602 }
603 pTerm->prereqAll = prereqAll;
drh0fcef5e2005-07-19 17:38:22 +0000604 pTerm->leftCursor = -1;
drh45b1ee42005-08-02 17:48:22 +0000605 pTerm->iParent = -1;
drhb52076c2006-01-23 13:22:09 +0000606 pTerm->eOperator = 0;
drh0fcef5e2005-07-19 17:38:22 +0000607 if( allowedOp(pExpr->op) && (pTerm->prereqRight & prereqLeft)==0 ){
608 Expr *pLeft = pExpr->pLeft;
609 Expr *pRight = pExpr->pRight;
610 if( pLeft->op==TK_COLUMN ){
611 pTerm->leftCursor = pLeft->iTable;
612 pTerm->leftColumn = pLeft->iColumn;
drhb52076c2006-01-23 13:22:09 +0000613 pTerm->eOperator = operatorMask(pExpr->op);
drh75897232000-05-29 14:26:00 +0000614 }
drh0fcef5e2005-07-19 17:38:22 +0000615 if( pRight && pRight->op==TK_COLUMN ){
616 WhereTerm *pNew;
617 Expr *pDup;
618 if( pTerm->leftCursor>=0 ){
drh9eb20282005-08-24 03:52:18 +0000619 int idxNew;
drh0fcef5e2005-07-19 17:38:22 +0000620 pDup = sqlite3ExprDup(pExpr);
drh9eb20282005-08-24 03:52:18 +0000621 idxNew = whereClauseInsert(pWC, pDup, TERM_VIRTUAL|TERM_DYNAMIC);
622 if( idxNew==0 ) return;
623 pNew = &pWC->a[idxNew];
624 pNew->iParent = idxTerm;
625 pTerm = &pWC->a[idxTerm];
drh45b1ee42005-08-02 17:48:22 +0000626 pTerm->nChild = 1;
627 pTerm->flags |= TERM_COPIED;
drh0fcef5e2005-07-19 17:38:22 +0000628 }else{
629 pDup = pExpr;
630 pNew = pTerm;
631 }
632 exprCommute(pDup);
633 pLeft = pDup->pLeft;
634 pNew->leftCursor = pLeft->iTable;
635 pNew->leftColumn = pLeft->iColumn;
636 pNew->prereqRight = prereqLeft;
637 pNew->prereqAll = prereqAll;
drhb52076c2006-01-23 13:22:09 +0000638 pNew->eOperator = operatorMask(pDup->op);
drh75897232000-05-29 14:26:00 +0000639 }
640 }
drhed378002005-07-28 23:12:08 +0000641
drhd2687b72005-08-12 22:56:09 +0000642#ifndef SQLITE_OMIT_BETWEEN_OPTIMIZATION
drhed378002005-07-28 23:12:08 +0000643 /* If a term is the BETWEEN operator, create two new virtual terms
644 ** that define the range that the BETWEEN implements.
645 */
646 else if( pExpr->op==TK_BETWEEN ){
647 ExprList *pList = pExpr->pList;
648 int i;
649 static const u8 ops[] = {TK_GE, TK_LE};
650 assert( pList!=0 );
651 assert( pList->nExpr==2 );
652 for(i=0; i<2; i++){
653 Expr *pNewExpr;
drh9eb20282005-08-24 03:52:18 +0000654 int idxNew;
drhed378002005-07-28 23:12:08 +0000655 pNewExpr = sqlite3Expr(ops[i], sqlite3ExprDup(pExpr->pLeft),
656 sqlite3ExprDup(pList->a[i].pExpr), 0);
drh9eb20282005-08-24 03:52:18 +0000657 idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
658 exprAnalyze(pSrc, pMaskSet, pWC, idxNew);
659 pTerm = &pWC->a[idxTerm];
660 pWC->a[idxNew].iParent = idxTerm;
drhed378002005-07-28 23:12:08 +0000661 }
drh45b1ee42005-08-02 17:48:22 +0000662 pTerm->nChild = 2;
drhed378002005-07-28 23:12:08 +0000663 }
drhd2687b72005-08-12 22:56:09 +0000664#endif /* SQLITE_OMIT_BETWEEN_OPTIMIZATION */
drhed378002005-07-28 23:12:08 +0000665
danielk19771576cd92006-01-14 08:02:28 +0000666#if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY)
drh6c30be82005-07-29 15:10:17 +0000667 /* Attempt to convert OR-connected terms into an IN operator so that
drhf5b11382005-09-17 13:07:13 +0000668 ** they can make use of indices. Example:
669 **
670 ** x = expr1 OR expr2 = x OR x = expr3
671 **
672 ** is converted into
673 **
674 ** x IN (expr1,expr2,expr3)
danielk19771576cd92006-01-14 08:02:28 +0000675 **
676 ** This optimization must be omitted if OMIT_SUBQUERY is defined because
677 ** the compiler for the the IN operator is part of sub-queries.
drh6c30be82005-07-29 15:10:17 +0000678 */
679 else if( pExpr->op==TK_OR ){
680 int ok;
681 int i, j;
682 int iColumn, iCursor;
683 WhereClause sOr;
684 WhereTerm *pOrTerm;
685
686 assert( (pTerm->flags & TERM_DYNAMIC)==0 );
drh9eb20282005-08-24 03:52:18 +0000687 whereClauseInit(&sOr, pWC->pParse);
drh6c30be82005-07-29 15:10:17 +0000688 whereSplit(&sOr, pExpr, TK_OR);
689 exprAnalyzeAll(pSrc, pMaskSet, &sOr);
690 assert( sOr.nTerm>0 );
691 j = 0;
692 do{
693 iColumn = sOr.a[j].leftColumn;
694 iCursor = sOr.a[j].leftCursor;
695 ok = iCursor>=0;
696 for(i=sOr.nTerm-1, pOrTerm=sOr.a; i>=0 && ok; i--, pOrTerm++){
drhb52076c2006-01-23 13:22:09 +0000697 if( pOrTerm->eOperator!=WO_EQ ){
drh6c30be82005-07-29 15:10:17 +0000698 goto or_not_possible;
699 }
700 if( pOrTerm->leftCursor==iCursor && pOrTerm->leftColumn==iColumn ){
701 pOrTerm->flags |= TERM_OR_OK;
drh45b1ee42005-08-02 17:48:22 +0000702 }else if( (pOrTerm->flags & TERM_COPIED)!=0 ||
drh6c30be82005-07-29 15:10:17 +0000703 ((pOrTerm->flags & TERM_VIRTUAL)!=0 &&
drh45b1ee42005-08-02 17:48:22 +0000704 (sOr.a[pOrTerm->iParent].flags & TERM_OR_OK)!=0) ){
drh6c30be82005-07-29 15:10:17 +0000705 pOrTerm->flags &= ~TERM_OR_OK;
706 }else{
707 ok = 0;
708 }
709 }
drh45b1ee42005-08-02 17:48:22 +0000710 }while( !ok && (sOr.a[j++].flags & TERM_COPIED)!=0 && j<sOr.nTerm );
drh6c30be82005-07-29 15:10:17 +0000711 if( ok ){
712 ExprList *pList = 0;
713 Expr *pNew, *pDup;
714 for(i=sOr.nTerm-1, pOrTerm=sOr.a; i>=0 && ok; i--, pOrTerm++){
715 if( (pOrTerm->flags & TERM_OR_OK)==0 ) continue;
716 pDup = sqlite3ExprDup(pOrTerm->pExpr->pRight);
717 pList = sqlite3ExprListAppend(pList, pDup, 0);
718 }
719 pDup = sqlite3Expr(TK_COLUMN, 0, 0, 0);
720 if( pDup ){
721 pDup->iTable = iCursor;
722 pDup->iColumn = iColumn;
723 }
724 pNew = sqlite3Expr(TK_IN, pDup, 0, 0);
drh53f733c2005-09-16 02:38:09 +0000725 if( pNew ){
drh9a5f7472005-11-26 14:24:40 +0000726 int idxNew;
drh54a167d2005-11-26 14:08:07 +0000727 transferJoinMarkings(pNew, pExpr);
drh53f733c2005-09-16 02:38:09 +0000728 pNew->pList = pList;
drh9a5f7472005-11-26 14:24:40 +0000729 idxNew = whereClauseInsert(pWC, pNew, TERM_VIRTUAL|TERM_DYNAMIC);
730 exprAnalyze(pSrc, pMaskSet, pWC, idxNew);
731 pTerm = &pWC->a[idxTerm];
732 pWC->a[idxNew].iParent = idxTerm;
733 pTerm->nChild = 1;
drh53f733c2005-09-16 02:38:09 +0000734 }else{
735 sqlite3ExprListDelete(pList);
736 }
drh6c30be82005-07-29 15:10:17 +0000737 }
738or_not_possible:
739 whereClauseClear(&sOr);
740 }
drhd2687b72005-08-12 22:56:09 +0000741#endif /* SQLITE_OMIT_OR_OPTIMIZATION */
742
743#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
744 /* Add constraints to reduce the search space on a LIKE or GLOB
745 ** operator.
746 */
drh9eb20282005-08-24 03:52:18 +0000747 if( isLikeOrGlob(pWC->pParse->db, pExpr, &nPattern, &isComplete) ){
drhd2687b72005-08-12 22:56:09 +0000748 Expr *pLeft, *pRight;
749 Expr *pStr1, *pStr2;
750 Expr *pNewExpr1, *pNewExpr2;
drh9eb20282005-08-24 03:52:18 +0000751 int idxNew1, idxNew2;
752
drhd2687b72005-08-12 22:56:09 +0000753 pLeft = pExpr->pList->a[1].pExpr;
754 pRight = pExpr->pList->a[0].pExpr;
755 pStr1 = sqlite3Expr(TK_STRING, 0, 0, 0);
756 if( pStr1 ){
757 sqlite3TokenCopy(&pStr1->token, &pRight->token);
758 pStr1->token.n = nPattern;
759 }
760 pStr2 = sqlite3ExprDup(pStr1);
761 if( pStr2 ){
762 assert( pStr2->token.dyn );
763 ++*(u8*)&pStr2->token.z[nPattern-1];
764 }
765 pNewExpr1 = sqlite3Expr(TK_GE, sqlite3ExprDup(pLeft), pStr1, 0);
drh9eb20282005-08-24 03:52:18 +0000766 idxNew1 = whereClauseInsert(pWC, pNewExpr1, TERM_VIRTUAL|TERM_DYNAMIC);
767 exprAnalyze(pSrc, pMaskSet, pWC, idxNew1);
drhd2687b72005-08-12 22:56:09 +0000768 pNewExpr2 = sqlite3Expr(TK_LT, sqlite3ExprDup(pLeft), pStr2, 0);
drh9eb20282005-08-24 03:52:18 +0000769 idxNew2 = whereClauseInsert(pWC, pNewExpr2, TERM_VIRTUAL|TERM_DYNAMIC);
770 exprAnalyze(pSrc, pMaskSet, pWC, idxNew2);
771 pTerm = &pWC->a[idxTerm];
drhd2687b72005-08-12 22:56:09 +0000772 if( isComplete ){
drh9eb20282005-08-24 03:52:18 +0000773 pWC->a[idxNew1].iParent = idxTerm;
774 pWC->a[idxNew2].iParent = idxTerm;
drhd2687b72005-08-12 22:56:09 +0000775 pTerm->nChild = 2;
776 }
777 }
778#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
drh7f375902006-06-13 17:38:59 +0000779
780#ifndef SQLITE_OMIT_VIRTUALTABLE
781 /* Add a WO_MATCH auxiliary term to the constraint set if the
782 ** current expression is of the form: column MATCH expr.
783 ** This information is used by the xBestIndex methods of
784 ** virtual tables. The native query optimizer does not attempt
785 ** to do anything with MATCH functions.
786 */
787 if( isMatchOfColumn(pExpr) ){
788 int idxNew;
789 Expr *pRight, *pLeft;
790 WhereTerm *pNewTerm;
791 Bitmask prereqColumn, prereqExpr;
792
793 pRight = pExpr->pList->a[0].pExpr;
794 pLeft = pExpr->pList->a[1].pExpr;
795 prereqExpr = exprTableUsage(pMaskSet, pRight);
796 prereqColumn = exprTableUsage(pMaskSet, pLeft);
797 if( (prereqExpr & prereqColumn)==0 ){
drh1a90e092006-06-14 22:07:10 +0000798 Expr *pNewExpr;
799 pNewExpr = sqlite3Expr(TK_MATCH, 0, sqlite3ExprDup(pRight), 0);
800 idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
drh7f375902006-06-13 17:38:59 +0000801 pNewTerm = &pWC->a[idxNew];
802 pNewTerm->prereqRight = prereqExpr;
803 pNewTerm->leftCursor = pLeft->iTable;
804 pNewTerm->leftColumn = pLeft->iColumn;
805 pNewTerm->eOperator = WO_MATCH;
806 pNewTerm->iParent = idxTerm;
807 pTerm = &pWC->a[idxNew];
808 pTerm->nChild = 1;
809 pTerm->flags |= TERM_COPIED;
810 pNewTerm->prereqAll = pTerm->prereqAll;
811 }
812 }
813#endif /* SQLITE_OMIT_VIRTUALTABLE */
drh75897232000-05-29 14:26:00 +0000814}
815
drh0fcef5e2005-07-19 17:38:22 +0000816
drh75897232000-05-29 14:26:00 +0000817/*
drh51669862004-12-18 18:40:26 +0000818** This routine decides if pIdx can be used to satisfy the ORDER BY
819** clause. If it can, it returns 1. If pIdx cannot satisfy the
820** ORDER BY clause, this routine returns 0.
821**
822** pOrderBy is an ORDER BY clause from a SELECT statement. pTab is the
823** left-most table in the FROM clause of that same SELECT statement and
824** the table has a cursor number of "base". pIdx is an index on pTab.
825**
826** nEqCol is the number of columns of pIdx that are used as equality
827** constraints. Any of these columns may be missing from the ORDER BY
828** clause and the match can still be a success.
829**
drh51669862004-12-18 18:40:26 +0000830** All terms of the ORDER BY that match against the index must be either
831** ASC or DESC. (Terms of the ORDER BY clause past the end of a UNIQUE
832** index do not need to satisfy this constraint.) The *pbRev value is
833** set to 1 if the ORDER BY clause is all DESC and it is set to 0 if
834** the ORDER BY clause is all ASC.
835*/
836static int isSortingIndex(
837 Parse *pParse, /* Parsing context */
838 Index *pIdx, /* The index we are testing */
drh74161702006-02-24 02:53:49 +0000839 int base, /* Cursor number for the table to be sorted */
drh51669862004-12-18 18:40:26 +0000840 ExprList *pOrderBy, /* The ORDER BY clause */
841 int nEqCol, /* Number of index columns with == constraints */
842 int *pbRev /* Set to 1 if ORDER BY is DESC */
843){
drhb46b5772005-08-29 16:40:52 +0000844 int i, j; /* Loop counters */
drh85eeb692005-12-21 03:16:42 +0000845 int sortOrder = 0; /* XOR of index and ORDER BY sort direction */
drhb46b5772005-08-29 16:40:52 +0000846 int nTerm; /* Number of ORDER BY terms */
847 struct ExprList_item *pTerm; /* A term of the ORDER BY clause */
drh51669862004-12-18 18:40:26 +0000848 sqlite3 *db = pParse->db;
849
850 assert( pOrderBy!=0 );
851 nTerm = pOrderBy->nExpr;
852 assert( nTerm>0 );
853
854 /* Match terms of the ORDER BY clause against columns of
855 ** the index.
856 */
857 for(i=j=0, pTerm=pOrderBy->a; j<nTerm && i<pIdx->nColumn; i++){
858 Expr *pExpr; /* The expression of the ORDER BY pTerm */
859 CollSeq *pColl; /* The collating sequence of pExpr */
drh85eeb692005-12-21 03:16:42 +0000860 int termSortOrder; /* Sort order for this term */
drh51669862004-12-18 18:40:26 +0000861
862 pExpr = pTerm->pExpr;
863 if( pExpr->op!=TK_COLUMN || pExpr->iTable!=base ){
864 /* Can not use an index sort on anything that is not a column in the
865 ** left-most table of the FROM clause */
866 return 0;
867 }
868 pColl = sqlite3ExprCollSeq(pParse, pExpr);
869 if( !pColl ) pColl = db->pDfltColl;
danielk1977b3bf5562006-01-10 17:58:23 +0000870 if( pExpr->iColumn!=pIdx->aiColumn[i] ||
871 sqlite3StrICmp(pColl->zName, pIdx->azColl[i]) ){
drh9012bcb2004-12-19 00:11:35 +0000872 /* Term j of the ORDER BY clause does not match column i of the index */
873 if( i<nEqCol ){
drh51669862004-12-18 18:40:26 +0000874 /* If an index column that is constrained by == fails to match an
875 ** ORDER BY term, that is OK. Just ignore that column of the index
876 */
877 continue;
878 }else{
879 /* If an index column fails to match and is not constrained by ==
880 ** then the index cannot satisfy the ORDER BY constraint.
881 */
882 return 0;
883 }
884 }
danielk1977b3bf5562006-01-10 17:58:23 +0000885 assert( pIdx->aSortOrder!=0 );
drh85eeb692005-12-21 03:16:42 +0000886 assert( pTerm->sortOrder==0 || pTerm->sortOrder==1 );
danielk1977b3bf5562006-01-10 17:58:23 +0000887 assert( pIdx->aSortOrder[i]==0 || pIdx->aSortOrder[i]==1 );
888 termSortOrder = pIdx->aSortOrder[i] ^ pTerm->sortOrder;
drh51669862004-12-18 18:40:26 +0000889 if( i>nEqCol ){
drh85eeb692005-12-21 03:16:42 +0000890 if( termSortOrder!=sortOrder ){
drh51669862004-12-18 18:40:26 +0000891 /* Indices can only be used if all ORDER BY terms past the
892 ** equality constraints are all either DESC or ASC. */
893 return 0;
894 }
895 }else{
drh85eeb692005-12-21 03:16:42 +0000896 sortOrder = termSortOrder;
drh51669862004-12-18 18:40:26 +0000897 }
898 j++;
899 pTerm++;
900 }
901
902 /* The index can be used for sorting if all terms of the ORDER BY clause
drh8718f522005-08-13 16:13:04 +0000903 ** are covered.
drh51669862004-12-18 18:40:26 +0000904 */
drh8718f522005-08-13 16:13:04 +0000905 if( j>=nTerm ){
drh85eeb692005-12-21 03:16:42 +0000906 *pbRev = sortOrder!=0;
drh51669862004-12-18 18:40:26 +0000907 return 1;
908 }
909 return 0;
910}
911
912/*
drhb6c29892004-11-22 19:12:19 +0000913** Check table to see if the ORDER BY clause in pOrderBy can be satisfied
914** by sorting in order of ROWID. Return true if so and set *pbRev to be
915** true for reverse ROWID and false for forward ROWID order.
916*/
917static int sortableByRowid(
918 int base, /* Cursor number for table to be sorted */
919 ExprList *pOrderBy, /* The ORDER BY clause */
920 int *pbRev /* Set to 1 if ORDER BY is DESC */
921){
922 Expr *p;
923
924 assert( pOrderBy!=0 );
925 assert( pOrderBy->nExpr>0 );
926 p = pOrderBy->a[0].pExpr;
drha21c8492005-09-01 17:47:51 +0000927 if( pOrderBy->nExpr==1 && p->op==TK_COLUMN && p->iTable==base
928 && p->iColumn==-1 ){
drhb6c29892004-11-22 19:12:19 +0000929 *pbRev = pOrderBy->a[0].sortOrder;
930 return 1;
931 }
932 return 0;
933}
934
drhfe05af82005-07-21 03:14:59 +0000935/*
drhb6fb62d2005-09-20 08:47:20 +0000936** Prepare a crude estimate of the logarithm of the input value.
drh28c4cf42005-07-27 20:41:43 +0000937** The results need not be exact. This is only used for estimating
938** the total cost of performing operatings with O(logN) or O(NlogN)
939** complexity. Because N is just a guess, it is no great tragedy if
940** logN is a little off.
drh28c4cf42005-07-27 20:41:43 +0000941*/
942static double estLog(double N){
drhb37df7b2005-10-13 02:09:49 +0000943 double logN = 1;
944 double x = 10;
drh28c4cf42005-07-27 20:41:43 +0000945 while( N>x ){
drhb37df7b2005-10-13 02:09:49 +0000946 logN += 1;
drh28c4cf42005-07-27 20:41:43 +0000947 x *= 10;
948 }
949 return logN;
950}
951
drh9eff6162006-06-12 21:59:13 +0000952#ifndef SQLITE_OMIT_VIRTUALTABLE
953/*
drh7f375902006-06-13 17:38:59 +0000954** Compute the best index for a virtual table.
955**
956** The best index is computed by the xBestIndex method of the virtual
957** table module. This routine is really just a wrapper that sets up
958** the sqlite3_index_info structure that is used to communicate with
959** xBestIndex.
960**
961** In a join, this routine might be called multiple times for the
962** same virtual table. The sqlite3_index_info structure is created
963** and initialized on the first invocation and reused on all subsequent
964** invocations. The sqlite3_index_info structure is also used when
965** code is generated to access the virtual table. The whereInfoDelete()
966** routine takes care of freeing the sqlite3_index_info structure after
967** everybody has finished with it.
drh9eff6162006-06-12 21:59:13 +0000968*/
969static double bestVirtualIndex(
970 Parse *pParse, /* The parsing context */
971 WhereClause *pWC, /* The WHERE clause */
972 struct SrcList_item *pSrc, /* The FROM clause term to search */
973 Bitmask notReady, /* Mask of cursors that are not available */
974 ExprList *pOrderBy, /* The order by clause */
975 int orderByUsable, /* True if we can potential sort */
976 sqlite3_index_info **ppIdxInfo /* Index information passed to xBestIndex */
977){
978 Table *pTab = pSrc->pTab;
979 sqlite3_index_info *pIdxInfo;
980 struct sqlite3_index_constraint *pIdxCons;
981 struct sqlite3_index_orderby *pIdxOrderBy;
982 struct sqlite3_index_constraint_usage *pUsage;
983 WhereTerm *pTerm;
984 int i, j;
985 int nOrderBy;
danielk197774cdba42006-06-19 12:02:58 +0000986 int rc;
drh9eff6162006-06-12 21:59:13 +0000987
988 /* If the sqlite3_index_info structure has not been previously
989 ** allocated and initialized for this virtual table, then allocate
990 ** and initialize it now
991 */
992 pIdxInfo = *ppIdxInfo;
993 if( pIdxInfo==0 ){
994 WhereTerm *pTerm;
995 int nTerm;
996
997 /* Count the number of possible WHERE clause constraints referring
998 ** to this virtual table */
999 for(i=nTerm=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
1000 if( pTerm->leftCursor != pSrc->iCursor ) continue;
1001 if( pTerm->eOperator==WO_IN ) continue;
1002 nTerm++;
1003 }
1004
1005 /* If the ORDER BY clause contains only columns in the current
1006 ** virtual table then allocate space for the aOrderBy part of
1007 ** the sqlite3_index_info structure.
1008 */
1009 nOrderBy = 0;
1010 if( pOrderBy ){
1011 for(i=0; i<pOrderBy->nExpr; i++){
1012 Expr *pExpr = pOrderBy->a[i].pExpr;
1013 if( pExpr->op!=TK_COLUMN || pExpr->iTable!=pSrc->iCursor ) break;
1014 }
1015 if( i==pOrderBy->nExpr ){
1016 nOrderBy = pOrderBy->nExpr;
1017 }
1018 }
1019
1020 /* Allocate the sqlite3_index_info structure
1021 */
1022 pIdxInfo = sqliteMalloc( sizeof(*pIdxInfo)
1023 + (sizeof(*pIdxCons) + sizeof(*pUsage))*nTerm
1024 + sizeof(*pIdxOrderBy)*nOrderBy );
1025 if( pIdxInfo==0 ){
1026 sqlite3ErrorMsg(pParse, "out of memory");
1027 return 0.0;
1028 }
1029 *ppIdxInfo = pIdxInfo;
1030
1031 /* Initialize the structure. The sqlite3_index_info structure contains
1032 ** many fields that are declared "const" to prevent xBestIndex from
1033 ** changing them. We have to do some funky casting in order to
1034 ** initialize those fields.
1035 */
1036 pIdxCons = (struct sqlite3_index_constraint*)&pIdxInfo[1];
1037 pIdxOrderBy = (struct sqlite3_index_orderby*)&pIdxCons[nTerm];
1038 pUsage = (struct sqlite3_index_constraint_usage*)&pIdxOrderBy[nOrderBy];
1039 *(int*)&pIdxInfo->nConstraint = nTerm;
1040 *(int*)&pIdxInfo->nOrderBy = nOrderBy;
1041 *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint = pIdxCons;
1042 *(struct sqlite3_index_orderby**)&pIdxInfo->aOrderBy = pIdxOrderBy;
1043 *(struct sqlite3_index_constraint_usage**)&pIdxInfo->aConstraintUsage =
1044 pUsage;
1045
1046 for(i=j=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
1047 if( pTerm->leftCursor != pSrc->iCursor ) continue;
1048 if( pTerm->eOperator==WO_IN ) continue;
1049 pIdxCons[j].iColumn = pTerm->leftColumn;
1050 pIdxCons[j].iTermOffset = i;
1051 pIdxCons[j].op = pTerm->eOperator;
drh7f375902006-06-13 17:38:59 +00001052 /* The direct assignment in the previous line is possible only because
1053 ** the WO_ and SQLITE_INDEX_CONSTRAINT_ codes are identical. The
1054 ** following asserts verify this fact. */
drh9eff6162006-06-12 21:59:13 +00001055 assert( WO_EQ==SQLITE_INDEX_CONSTRAINT_EQ );
1056 assert( WO_LT==SQLITE_INDEX_CONSTRAINT_LT );
1057 assert( WO_LE==SQLITE_INDEX_CONSTRAINT_LE );
1058 assert( WO_GT==SQLITE_INDEX_CONSTRAINT_GT );
1059 assert( WO_GE==SQLITE_INDEX_CONSTRAINT_GE );
drh7f375902006-06-13 17:38:59 +00001060 assert( WO_MATCH==SQLITE_INDEX_CONSTRAINT_MATCH );
1061 assert( pTerm->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE|WO_MATCH) );
drh9eff6162006-06-12 21:59:13 +00001062 j++;
1063 }
1064 for(i=0; i<nOrderBy; i++){
1065 Expr *pExpr = pOrderBy->a[i].pExpr;
1066 pIdxOrderBy[i].iColumn = pExpr->iColumn;
1067 pIdxOrderBy[i].desc = pOrderBy->a[i].sortOrder;
1068 }
1069 }
1070
drh7f375902006-06-13 17:38:59 +00001071 /* At this point, the sqlite3_index_info structure that pIdxInfo points
1072 ** to will have been initialized, either during the current invocation or
1073 ** during some prior invocation. Now we just have to customize the
1074 ** details of pIdxInfo for the current invocation and pass it to
1075 ** xBestIndex.
1076 */
1077
drh9eff6162006-06-12 21:59:13 +00001078 /* The module name must be defined */
1079 assert( pTab->azModuleArg && pTab->azModuleArg[0] );
1080 if( pTab->pVtab==0 ){
1081 sqlite3ErrorMsg(pParse, "undefined module %s for table %s",
1082 pTab->azModuleArg[0], pTab->zName);
1083 return 0.0;
1084 }
1085
1086 /* Set the aConstraint[].usable fields and initialize all
drh7f375902006-06-13 17:38:59 +00001087 ** output variables to zero.
1088 **
1089 ** aConstraint[].usable is true for constraints where the right-hand
1090 ** side contains only references to tables to the left of the current
1091 ** table. In other words, if the constraint is of the form:
1092 **
1093 ** column = expr
1094 **
1095 ** and we are evaluating a join, then the constraint on column is
1096 ** only valid if all tables referenced in expr occur to the left
1097 ** of the table containing column.
1098 **
1099 ** The aConstraints[] array contains entries for all constraints
1100 ** on the current table. That way we only have to compute it once
1101 ** even though we might try to pick the best index multiple times.
1102 ** For each attempt at picking an index, the order of tables in the
1103 ** join might be different so we have to recompute the usable flag
1104 ** each time.
drh9eff6162006-06-12 21:59:13 +00001105 */
1106 pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint;
1107 pUsage = pIdxInfo->aConstraintUsage;
1108 for(i=0; i<pIdxInfo->nConstraint; i++, pIdxCons++){
1109 j = pIdxCons->iTermOffset;
1110 pTerm = &pWC->a[j];
1111 pIdxCons->usable = (pTerm->prereqRight & notReady)==0;
1112 }
1113 memset(pUsage, 0, sizeof(pUsage[0])*pIdxInfo->nConstraint);
drh4be8b512006-06-13 23:51:34 +00001114 if( pIdxInfo->needToFreeIdxStr ){
1115 sqlite3_free(pIdxInfo->idxStr);
1116 }
1117 pIdxInfo->idxStr = 0;
1118 pIdxInfo->idxNum = 0;
1119 pIdxInfo->needToFreeIdxStr = 0;
drh9eff6162006-06-12 21:59:13 +00001120 pIdxInfo->orderByConsumed = 0;
danielk197793626f42006-06-20 13:07:27 +00001121 pIdxInfo->estimatedCost = SQLITE_BIG_DBL / 2.0;
drh9eff6162006-06-12 21:59:13 +00001122 nOrderBy = pIdxInfo->nOrderBy;
1123 if( pIdxInfo->nOrderBy && !orderByUsable ){
drha967e882006-06-13 01:04:52 +00001124 *(int*)&pIdxInfo->nOrderBy = 0;
drh9eff6162006-06-12 21:59:13 +00001125 }
danielk197774cdba42006-06-19 12:02:58 +00001126
1127 sqlite3SafetyOff(pParse->db);
danielk1977be718892006-06-23 08:05:19 +00001128 rc = pTab->pVtab->pModule->xBestIndex(pTab->pVtab, pIdxInfo);
danielk197774cdba42006-06-19 12:02:58 +00001129 if( rc!=SQLITE_OK ){
danielk1977be718892006-06-23 08:05:19 +00001130 if( rc==SQLITE_NOMEM ){
1131 sqlite3FailedMalloc();
1132 }else {
1133 sqlite3ErrorMsg(pParse, "%s", sqlite3ErrStr(rc));
1134 }
1135 sqlite3SafetyOn(pParse->db);
1136 }else{
1137 rc = sqlite3SafetyOn(pParse->db);
danielk197774cdba42006-06-19 12:02:58 +00001138 }
1139
drha967e882006-06-13 01:04:52 +00001140 *(int*)&pIdxInfo->nOrderBy = nOrderBy;
drh9eff6162006-06-12 21:59:13 +00001141 return pIdxInfo->estimatedCost;
1142}
1143#endif /* SQLITE_OMIT_VIRTUALTABLE */
1144
drh28c4cf42005-07-27 20:41:43 +00001145/*
drh51147ba2005-07-23 22:59:55 +00001146** Find the best index for accessing a particular table. Return a pointer
1147** to the index, flags that describe how the index should be used, the
drha6110402005-07-28 20:51:19 +00001148** number of equality constraints, and the "cost" for this index.
drh51147ba2005-07-23 22:59:55 +00001149**
1150** The lowest cost index wins. The cost is an estimate of the amount of
1151** CPU and disk I/O need to process the request using the selected index.
1152** Factors that influence cost include:
1153**
1154** * The estimated number of rows that will be retrieved. (The
1155** fewer the better.)
1156**
1157** * Whether or not sorting must occur.
1158**
1159** * Whether or not there must be separate lookups in the
1160** index and in the main table.
1161**
drhfe05af82005-07-21 03:14:59 +00001162*/
1163static double bestIndex(
1164 Parse *pParse, /* The parsing context */
1165 WhereClause *pWC, /* The WHERE clause */
1166 struct SrcList_item *pSrc, /* The FROM clause term to search */
1167 Bitmask notReady, /* Mask of cursors that are not available */
1168 ExprList *pOrderBy, /* The order by clause */
1169 Index **ppIndex, /* Make *ppIndex point to the best index */
drh51147ba2005-07-23 22:59:55 +00001170 int *pFlags, /* Put flags describing this choice in *pFlags */
1171 int *pnEq /* Put the number of == or IN constraints here */
drhfe05af82005-07-21 03:14:59 +00001172){
1173 WhereTerm *pTerm;
drh51147ba2005-07-23 22:59:55 +00001174 Index *bestIdx = 0; /* Index that gives the lowest cost */
drhb37df7b2005-10-13 02:09:49 +00001175 double lowestCost; /* The cost of using bestIdx */
drh51147ba2005-07-23 22:59:55 +00001176 int bestFlags = 0; /* Flags associated with bestIdx */
1177 int bestNEq = 0; /* Best value for nEq */
1178 int iCur = pSrc->iCursor; /* The cursor of the table to be accessed */
1179 Index *pProbe; /* An index we are evaluating */
1180 int rev; /* True to scan in reverse order */
1181 int flags; /* Flags associated with pProbe */
1182 int nEq; /* Number of == or IN constraints */
1183 double cost; /* Cost of using pProbe */
drhfe05af82005-07-21 03:14:59 +00001184
drh51147ba2005-07-23 22:59:55 +00001185 TRACE(("bestIndex: tbl=%s notReady=%x\n", pSrc->pTab->zName, notReady));
drhb37df7b2005-10-13 02:09:49 +00001186 lowestCost = SQLITE_BIG_DBL;
drh4dd238a2006-03-28 23:55:57 +00001187 pProbe = pSrc->pTab->pIndex;
1188
1189 /* If the table has no indices and there are no terms in the where
1190 ** clause that refer to the ROWID, then we will never be able to do
1191 ** anything other than a full table scan on this table. We might as
1192 ** well put it first in the join order. That way, perhaps it can be
1193 ** referenced by other tables in the join.
1194 */
1195 if( pProbe==0 &&
1196 findTerm(pWC, iCur, -1, 0, WO_EQ|WO_IN|WO_LT|WO_LE|WO_GT|WO_GE,0)==0 &&
1197 (pOrderBy==0 || !sortableByRowid(iCur, pOrderBy, &rev)) ){
1198 *pFlags = 0;
1199 *ppIndex = 0;
1200 *pnEq = 0;
1201 return 0.0;
1202 }
drh51147ba2005-07-23 22:59:55 +00001203
1204 /* Check for a rowid=EXPR or rowid IN (...) constraints
drhfe05af82005-07-21 03:14:59 +00001205 */
1206 pTerm = findTerm(pWC, iCur, -1, notReady, WO_EQ|WO_IN, 0);
1207 if( pTerm ){
drha6110402005-07-28 20:51:19 +00001208 Expr *pExpr;
drhfe05af82005-07-21 03:14:59 +00001209 *ppIndex = 0;
drh51147ba2005-07-23 22:59:55 +00001210 bestFlags = WHERE_ROWID_EQ;
drhb52076c2006-01-23 13:22:09 +00001211 if( pTerm->eOperator & WO_EQ ){
drh28c4cf42005-07-27 20:41:43 +00001212 /* Rowid== is always the best pick. Look no further. Because only
1213 ** a single row is generated, output is always in sorted order */
drh943af3c2005-07-29 19:43:58 +00001214 *pFlags = WHERE_ROWID_EQ | WHERE_UNIQUE;
drh51147ba2005-07-23 22:59:55 +00001215 *pnEq = 1;
drh51147ba2005-07-23 22:59:55 +00001216 TRACE(("... best is rowid\n"));
1217 return 0.0;
drha6110402005-07-28 20:51:19 +00001218 }else if( (pExpr = pTerm->pExpr)->pList!=0 ){
drh28c4cf42005-07-27 20:41:43 +00001219 /* Rowid IN (LIST): cost is NlogN where N is the number of list
1220 ** elements. */
drha6110402005-07-28 20:51:19 +00001221 lowestCost = pExpr->pList->nExpr;
drh28c4cf42005-07-27 20:41:43 +00001222 lowestCost *= estLog(lowestCost);
drhfe05af82005-07-21 03:14:59 +00001223 }else{
drh28c4cf42005-07-27 20:41:43 +00001224 /* Rowid IN (SELECT): cost is NlogN where N is the number of rows
1225 ** in the result of the inner select. We have no way to estimate
1226 ** that value so make a wild guess. */
drhb37df7b2005-10-13 02:09:49 +00001227 lowestCost = 200;
drhfe05af82005-07-21 03:14:59 +00001228 }
drh3adc9ce2005-07-28 16:51:51 +00001229 TRACE(("... rowid IN cost: %.9g\n", lowestCost));
drhfe05af82005-07-21 03:14:59 +00001230 }
1231
drh28c4cf42005-07-27 20:41:43 +00001232 /* Estimate the cost of a table scan. If we do not know how many
1233 ** entries are in the table, use 1 million as a guess.
drhfe05af82005-07-21 03:14:59 +00001234 */
drhb37df7b2005-10-13 02:09:49 +00001235 cost = pProbe ? pProbe->aiRowEst[0] : 1000000;
drh3adc9ce2005-07-28 16:51:51 +00001236 TRACE(("... table scan base cost: %.9g\n", cost));
drh28c4cf42005-07-27 20:41:43 +00001237 flags = WHERE_ROWID_RANGE;
1238
1239 /* Check for constraints on a range of rowids in a table scan.
1240 */
drhfe05af82005-07-21 03:14:59 +00001241 pTerm = findTerm(pWC, iCur, -1, notReady, WO_LT|WO_LE|WO_GT|WO_GE, 0);
1242 if( pTerm ){
drh51147ba2005-07-23 22:59:55 +00001243 if( findTerm(pWC, iCur, -1, notReady, WO_LT|WO_LE, 0) ){
1244 flags |= WHERE_TOP_LIMIT;
drhb37df7b2005-10-13 02:09:49 +00001245 cost /= 3; /* Guess that rowid<EXPR eliminates two-thirds or rows */
drhfe05af82005-07-21 03:14:59 +00001246 }
drh51147ba2005-07-23 22:59:55 +00001247 if( findTerm(pWC, iCur, -1, notReady, WO_GT|WO_GE, 0) ){
1248 flags |= WHERE_BTM_LIMIT;
drhb37df7b2005-10-13 02:09:49 +00001249 cost /= 3; /* Guess that rowid>EXPR eliminates two-thirds of rows */
drhfe05af82005-07-21 03:14:59 +00001250 }
drh3adc9ce2005-07-28 16:51:51 +00001251 TRACE(("... rowid range reduces cost to %.9g\n", cost));
drh51147ba2005-07-23 22:59:55 +00001252 }else{
1253 flags = 0;
1254 }
drh28c4cf42005-07-27 20:41:43 +00001255
1256 /* If the table scan does not satisfy the ORDER BY clause, increase
1257 ** the cost by NlogN to cover the expense of sorting. */
1258 if( pOrderBy ){
1259 if( sortableByRowid(iCur, pOrderBy, &rev) ){
1260 flags |= WHERE_ORDERBY|WHERE_ROWID_RANGE;
1261 if( rev ){
1262 flags |= WHERE_REVERSE;
1263 }
1264 }else{
1265 cost += cost*estLog(cost);
drh3adc9ce2005-07-28 16:51:51 +00001266 TRACE(("... sorting increases cost to %.9g\n", cost));
drh51147ba2005-07-23 22:59:55 +00001267 }
drh51147ba2005-07-23 22:59:55 +00001268 }
1269 if( cost<lowestCost ){
1270 lowestCost = cost;
drhfe05af82005-07-21 03:14:59 +00001271 bestFlags = flags;
1272 }
1273
1274 /* Look at each index.
1275 */
drh51147ba2005-07-23 22:59:55 +00001276 for(; pProbe; pProbe=pProbe->pNext){
1277 int i; /* Loop counter */
drhb37df7b2005-10-13 02:09:49 +00001278 double inMultiplier = 1;
drh51147ba2005-07-23 22:59:55 +00001279
1280 TRACE(("... index %s:\n", pProbe->zName));
drhfe05af82005-07-21 03:14:59 +00001281
1282 /* Count the number of columns in the index that are satisfied
1283 ** by x=EXPR constraints or x IN (...) constraints.
1284 */
drh51147ba2005-07-23 22:59:55 +00001285 flags = 0;
drhfe05af82005-07-21 03:14:59 +00001286 for(i=0; i<pProbe->nColumn; i++){
1287 int j = pProbe->aiColumn[i];
1288 pTerm = findTerm(pWC, iCur, j, notReady, WO_EQ|WO_IN, pProbe);
1289 if( pTerm==0 ) break;
drh51147ba2005-07-23 22:59:55 +00001290 flags |= WHERE_COLUMN_EQ;
drhb52076c2006-01-23 13:22:09 +00001291 if( pTerm->eOperator & WO_IN ){
drha6110402005-07-28 20:51:19 +00001292 Expr *pExpr = pTerm->pExpr;
drh51147ba2005-07-23 22:59:55 +00001293 flags |= WHERE_COLUMN_IN;
drha6110402005-07-28 20:51:19 +00001294 if( pExpr->pSelect!=0 ){
drhffe0f892006-05-11 13:26:25 +00001295 inMultiplier *= 25;
drha6110402005-07-28 20:51:19 +00001296 }else if( pExpr->pList!=0 ){
drhb37df7b2005-10-13 02:09:49 +00001297 inMultiplier *= pExpr->pList->nExpr + 1;
drhfe05af82005-07-21 03:14:59 +00001298 }
1299 }
1300 }
drh28c4cf42005-07-27 20:41:43 +00001301 cost = pProbe->aiRowEst[i] * inMultiplier * estLog(inMultiplier);
drh51147ba2005-07-23 22:59:55 +00001302 nEq = i;
drh943af3c2005-07-29 19:43:58 +00001303 if( pProbe->onError!=OE_None && (flags & WHERE_COLUMN_IN)==0
1304 && nEq==pProbe->nColumn ){
1305 flags |= WHERE_UNIQUE;
1306 }
drh3adc9ce2005-07-28 16:51:51 +00001307 TRACE(("...... nEq=%d inMult=%.9g cost=%.9g\n", nEq, inMultiplier, cost));
drhfe05af82005-07-21 03:14:59 +00001308
drh51147ba2005-07-23 22:59:55 +00001309 /* Look for range constraints
drhfe05af82005-07-21 03:14:59 +00001310 */
drh51147ba2005-07-23 22:59:55 +00001311 if( nEq<pProbe->nColumn ){
1312 int j = pProbe->aiColumn[nEq];
1313 pTerm = findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE|WO_GT|WO_GE, pProbe);
1314 if( pTerm ){
drha6110402005-07-28 20:51:19 +00001315 flags |= WHERE_COLUMN_RANGE;
drh51147ba2005-07-23 22:59:55 +00001316 if( findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE, pProbe) ){
1317 flags |= WHERE_TOP_LIMIT;
drhb37df7b2005-10-13 02:09:49 +00001318 cost /= 3;
drh51147ba2005-07-23 22:59:55 +00001319 }
1320 if( findTerm(pWC, iCur, j, notReady, WO_GT|WO_GE, pProbe) ){
1321 flags |= WHERE_BTM_LIMIT;
drhb37df7b2005-10-13 02:09:49 +00001322 cost /= 3;
drh51147ba2005-07-23 22:59:55 +00001323 }
drh3adc9ce2005-07-28 16:51:51 +00001324 TRACE(("...... range reduces cost to %.9g\n", cost));
drh51147ba2005-07-23 22:59:55 +00001325 }
1326 }
1327
drh28c4cf42005-07-27 20:41:43 +00001328 /* Add the additional cost of sorting if that is a factor.
drh51147ba2005-07-23 22:59:55 +00001329 */
drh28c4cf42005-07-27 20:41:43 +00001330 if( pOrderBy ){
1331 if( (flags & WHERE_COLUMN_IN)==0 &&
drh74161702006-02-24 02:53:49 +00001332 isSortingIndex(pParse,pProbe,iCur,pOrderBy,nEq,&rev) ){
drh28c4cf42005-07-27 20:41:43 +00001333 if( flags==0 ){
1334 flags = WHERE_COLUMN_RANGE;
1335 }
1336 flags |= WHERE_ORDERBY;
1337 if( rev ){
1338 flags |= WHERE_REVERSE;
1339 }
1340 }else{
1341 cost += cost*estLog(cost);
drh3adc9ce2005-07-28 16:51:51 +00001342 TRACE(("...... orderby increases cost to %.9g\n", cost));
drh51147ba2005-07-23 22:59:55 +00001343 }
drhfe05af82005-07-21 03:14:59 +00001344 }
1345
1346 /* Check to see if we can get away with using just the index without
drh51147ba2005-07-23 22:59:55 +00001347 ** ever reading the table. If that is the case, then halve the
1348 ** cost of this index.
drhfe05af82005-07-21 03:14:59 +00001349 */
drh51147ba2005-07-23 22:59:55 +00001350 if( flags && pSrc->colUsed < (((Bitmask)1)<<(BMS-1)) ){
drhfe05af82005-07-21 03:14:59 +00001351 Bitmask m = pSrc->colUsed;
1352 int j;
1353 for(j=0; j<pProbe->nColumn; j++){
1354 int x = pProbe->aiColumn[j];
1355 if( x<BMS-1 ){
1356 m &= ~(((Bitmask)1)<<x);
1357 }
1358 }
1359 if( m==0 ){
1360 flags |= WHERE_IDX_ONLY;
drhb37df7b2005-10-13 02:09:49 +00001361 cost /= 2;
drh3adc9ce2005-07-28 16:51:51 +00001362 TRACE(("...... idx-only reduces cost to %.9g\n", cost));
drhfe05af82005-07-21 03:14:59 +00001363 }
1364 }
1365
drh51147ba2005-07-23 22:59:55 +00001366 /* If this index has achieved the lowest cost so far, then use it.
drhfe05af82005-07-21 03:14:59 +00001367 */
drh51147ba2005-07-23 22:59:55 +00001368 if( cost < lowestCost ){
drhfe05af82005-07-21 03:14:59 +00001369 bestIdx = pProbe;
drh51147ba2005-07-23 22:59:55 +00001370 lowestCost = cost;
drha6110402005-07-28 20:51:19 +00001371 assert( flags!=0 );
drhfe05af82005-07-21 03:14:59 +00001372 bestFlags = flags;
drh51147ba2005-07-23 22:59:55 +00001373 bestNEq = nEq;
drhfe05af82005-07-21 03:14:59 +00001374 }
1375 }
1376
drhfe05af82005-07-21 03:14:59 +00001377 /* Report the best result
1378 */
1379 *ppIndex = bestIdx;
drh3adc9ce2005-07-28 16:51:51 +00001380 TRACE(("best index is %s, cost=%.9g, flags=%x, nEq=%d\n",
drh51147ba2005-07-23 22:59:55 +00001381 bestIdx ? bestIdx->zName : "(none)", lowestCost, bestFlags, bestNEq));
drhfe05af82005-07-21 03:14:59 +00001382 *pFlags = bestFlags;
drh51147ba2005-07-23 22:59:55 +00001383 *pnEq = bestNEq;
1384 return lowestCost;
drhfe05af82005-07-21 03:14:59 +00001385}
1386
drhb6c29892004-11-22 19:12:19 +00001387
1388/*
drh2ffb1182004-07-19 19:14:01 +00001389** Disable a term in the WHERE clause. Except, do not disable the term
1390** if it controls a LEFT OUTER JOIN and it did not originate in the ON
1391** or USING clause of that join.
1392**
1393** Consider the term t2.z='ok' in the following queries:
1394**
1395** (1) SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x WHERE t2.z='ok'
1396** (2) SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x AND t2.z='ok'
1397** (3) SELECT * FROM t1, t2 WHERE t1.a=t2.x AND t2.z='ok'
1398**
drh23bf66d2004-12-14 03:34:34 +00001399** The t2.z='ok' is disabled in the in (2) because it originates
drh2ffb1182004-07-19 19:14:01 +00001400** in the ON clause. The term is disabled in (3) because it is not part
1401** of a LEFT OUTER JOIN. In (1), the term is not disabled.
1402**
1403** Disabling a term causes that term to not be tested in the inner loop
drhb6fb62d2005-09-20 08:47:20 +00001404** of the join. Disabling is an optimization. When terms are satisfied
1405** by indices, we disable them to prevent redundant tests in the inner
1406** loop. We would get the correct results if nothing were ever disabled,
1407** but joins might run a little slower. The trick is to disable as much
1408** as we can without disabling too much. If we disabled in (1), we'd get
1409** the wrong answer. See ticket #813.
drh2ffb1182004-07-19 19:14:01 +00001410*/
drh0fcef5e2005-07-19 17:38:22 +00001411static void disableTerm(WhereLevel *pLevel, WhereTerm *pTerm){
1412 if( pTerm
1413 && (pTerm->flags & TERM_CODED)==0
1414 && (pLevel->iLeftJoin==0 || ExprHasProperty(pTerm->pExpr, EP_FromJoin))
1415 ){
1416 pTerm->flags |= TERM_CODED;
drh45b1ee42005-08-02 17:48:22 +00001417 if( pTerm->iParent>=0 ){
1418 WhereTerm *pOther = &pTerm->pWC->a[pTerm->iParent];
1419 if( (--pOther->nChild)==0 ){
drhed378002005-07-28 23:12:08 +00001420 disableTerm(pLevel, pOther);
1421 }
drh0fcef5e2005-07-19 17:38:22 +00001422 }
drh2ffb1182004-07-19 19:14:01 +00001423 }
1424}
1425
1426/*
drh94a11212004-09-25 13:12:14 +00001427** Generate code that builds a probe for an index. Details:
1428**
1429** * Check the top nColumn entries on the stack. If any
1430** of those entries are NULL, jump immediately to brk,
1431** which is the loop exit, since no index entry will match
danielk1977327bd592006-01-13 13:01:19 +00001432** if any part of the key is NULL. Pop (nColumn+nExtra)
1433** elements from the stack.
drh94a11212004-09-25 13:12:14 +00001434**
1435** * Construct a probe entry from the top nColumn entries in
danielk1977327bd592006-01-13 13:01:19 +00001436** the stack with affinities appropriate for index pIdx.
1437** Only nColumn elements are popped from the stack in this case
1438** (by OP_MakeRecord).
1439**
drh94a11212004-09-25 13:12:14 +00001440*/
danielk1977327bd592006-01-13 13:01:19 +00001441static void buildIndexProbe(
1442 Vdbe *v,
1443 int nColumn,
1444 int nExtra,
1445 int brk,
1446 Index *pIdx
1447){
drh94a11212004-09-25 13:12:14 +00001448 sqlite3VdbeAddOp(v, OP_NotNull, -nColumn, sqlite3VdbeCurrentAddr(v)+3);
danielk1977327bd592006-01-13 13:01:19 +00001449 sqlite3VdbeAddOp(v, OP_Pop, nColumn+nExtra, 0);
drh94a11212004-09-25 13:12:14 +00001450 sqlite3VdbeAddOp(v, OP_Goto, 0, brk);
1451 sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
1452 sqlite3IndexAffinityStr(v, pIdx);
1453}
1454
drhe8b97272005-07-19 22:22:12 +00001455
1456/*
drh51147ba2005-07-23 22:59:55 +00001457** Generate code for a single equality term of the WHERE clause. An equality
1458** term can be either X=expr or X IN (...). pTerm is the term to be
1459** coded.
1460**
1461** The current value for the constraint is left on the top of the stack.
1462**
1463** For a constraint of the form X=expr, the expression is evaluated and its
1464** result is left on the stack. For constraints of the form X IN (...)
1465** this routine sets up a loop that will iterate over all values of X.
drh94a11212004-09-25 13:12:14 +00001466*/
1467static void codeEqualityTerm(
1468 Parse *pParse, /* The parsing context */
drhe23399f2005-07-22 00:31:39 +00001469 WhereTerm *pTerm, /* The term of the WHERE clause to be coded */
drh94a11212004-09-25 13:12:14 +00001470 int brk, /* Jump here to abandon the loop */
1471 WhereLevel *pLevel /* When level of the FROM clause we are working on */
1472){
drh0fcef5e2005-07-19 17:38:22 +00001473 Expr *pX = pTerm->pExpr;
drh94a11212004-09-25 13:12:14 +00001474 if( pX->op!=TK_IN ){
1475 assert( pX->op==TK_EQ );
1476 sqlite3ExprCode(pParse, pX->pRight);
danielk1977b3bce662005-01-29 08:32:43 +00001477#ifndef SQLITE_OMIT_SUBQUERY
drh94a11212004-09-25 13:12:14 +00001478 }else{
danielk1977b3bce662005-01-29 08:32:43 +00001479 int iTab;
drhe23399f2005-07-22 00:31:39 +00001480 int *aIn;
drh94a11212004-09-25 13:12:14 +00001481 Vdbe *v = pParse->pVdbe;
danielk1977b3bce662005-01-29 08:32:43 +00001482
1483 sqlite3CodeSubselect(pParse, pX);
1484 iTab = pX->iTable;
drhffe0f892006-05-11 13:26:25 +00001485 sqlite3VdbeAddOp(v, OP_Rewind, iTab, 0);
danielk1977b3bce662005-01-29 08:32:43 +00001486 VdbeComment((v, "# %.*s", pX->span.n, pX->span.z));
drhe23399f2005-07-22 00:31:39 +00001487 pLevel->nIn++;
danielk1977e7259292006-01-13 06:33:23 +00001488 sqliteReallocOrFree((void**)&pLevel->aInLoop,
drhffe0f892006-05-11 13:26:25 +00001489 sizeof(pLevel->aInLoop[0])*2*pLevel->nIn);
drh53f733c2005-09-16 02:38:09 +00001490 aIn = pLevel->aInLoop;
drhe23399f2005-07-22 00:31:39 +00001491 if( aIn ){
drhffe0f892006-05-11 13:26:25 +00001492 aIn += pLevel->nIn*2 - 2;
1493 aIn[0] = iTab;
1494 aIn[1] = sqlite3VdbeAddOp(v, OP_Column, iTab, 0);
drha6110402005-07-28 20:51:19 +00001495 }else{
1496 pLevel->nIn = 0;
drhe23399f2005-07-22 00:31:39 +00001497 }
danielk1977b3bce662005-01-29 08:32:43 +00001498#endif
drh94a11212004-09-25 13:12:14 +00001499 }
drh0fcef5e2005-07-19 17:38:22 +00001500 disableTerm(pLevel, pTerm);
drh94a11212004-09-25 13:12:14 +00001501}
1502
drh51147ba2005-07-23 22:59:55 +00001503/*
1504** Generate code that will evaluate all == and IN constraints for an
1505** index. The values for all constraints are left on the stack.
1506**
1507** For example, consider table t1(a,b,c,d,e,f) with index i1(a,b,c).
1508** Suppose the WHERE clause is this: a==5 AND b IN (1,2,3) AND c>5 AND c<10
1509** The index has as many as three equality constraints, but in this
1510** example, the third "c" value is an inequality. So only two
1511** constraints are coded. This routine will generate code to evaluate
1512** a==5 and b IN (1,2,3). The current values for a and b will be left
1513** on the stack - a is the deepest and b the shallowest.
1514**
1515** In the example above nEq==2. But this subroutine works for any value
1516** of nEq including 0. If nEq==0, this routine is nearly a no-op.
1517** The only thing it does is allocate the pLevel->iMem memory cell.
1518**
1519** This routine always allocates at least one memory cell and puts
1520** the address of that memory cell in pLevel->iMem. The code that
1521** calls this routine will use pLevel->iMem to store the termination
1522** key value of the loop. If one or more IN operators appear, then
1523** this routine allocates an additional nEq memory cells for internal
1524** use.
1525*/
1526static void codeAllEqualityTerms(
1527 Parse *pParse, /* Parsing context */
1528 WhereLevel *pLevel, /* Which nested loop of the FROM we are coding */
1529 WhereClause *pWC, /* The WHERE clause */
1530 Bitmask notReady, /* Which parts of FROM have not yet been coded */
1531 int brk /* Jump here to end the loop */
1532){
1533 int nEq = pLevel->nEq; /* The number of == or IN constraints to code */
1534 int termsInMem = 0; /* If true, store value in mem[] cells */
1535 Vdbe *v = pParse->pVdbe; /* The virtual machine under construction */
1536 Index *pIdx = pLevel->pIdx; /* The index being used for this loop */
1537 int iCur = pLevel->iTabCur; /* The cursor of the table */
1538 WhereTerm *pTerm; /* A single constraint term */
1539 int j; /* Loop counter */
1540
1541 /* Figure out how many memory cells we will need then allocate them.
1542 ** We always need at least one used to store the loop terminator
1543 ** value. If there are IN operators we'll need one for each == or
1544 ** IN constraint.
1545 */
1546 pLevel->iMem = pParse->nMem++;
1547 if( pLevel->flags & WHERE_COLUMN_IN ){
1548 pParse->nMem += pLevel->nEq;
1549 termsInMem = 1;
1550 }
1551
1552 /* Evaluate the equality constraints
1553 */
drh8b3d9902005-08-19 00:14:42 +00001554 for(j=0; j<pIdx->nColumn; j++){
drh51147ba2005-07-23 22:59:55 +00001555 int k = pIdx->aiColumn[j];
1556 pTerm = findTerm(pWC, iCur, k, notReady, WO_EQ|WO_IN, pIdx);
1557 if( pTerm==0 ) break;
1558 assert( (pTerm->flags & TERM_CODED)==0 );
1559 codeEqualityTerm(pParse, pTerm, brk, pLevel);
1560 if( termsInMem ){
1561 sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem+j+1, 1);
1562 }
1563 }
1564 assert( j==nEq );
1565
1566 /* Make sure all the constraint values are on the top of the stack
1567 */
1568 if( termsInMem ){
1569 for(j=0; j<nEq; j++){
1570 sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem+j+1, 0);
1571 }
1572 }
1573}
1574
drh549c8b62005-09-19 13:15:23 +00001575#if defined(SQLITE_TEST)
drh84bfda42005-07-15 13:05:21 +00001576/*
1577** The following variable holds a text description of query plan generated
1578** by the most recent call to sqlite3WhereBegin(). Each call to WhereBegin
1579** overwrites the previous. This information is used for testing and
1580** analysis only.
1581*/
1582char sqlite3_query_plan[BMS*2*40]; /* Text of the join */
1583static int nQPlan = 0; /* Next free slow in _query_plan[] */
1584
1585#endif /* SQLITE_TEST */
1586
1587
drh9eff6162006-06-12 21:59:13 +00001588/*
1589** Free a WhereInfo structure
1590*/
1591static void whereInfoFree(WhereInfo *pWInfo){
1592 if( pWInfo ){
1593 int i;
1594 for(i=0; i<pWInfo->nLevel; i++){
drh4be8b512006-06-13 23:51:34 +00001595 sqlite3_index_info *pInfo = pWInfo->a[i].pIdxInfo;
1596 if( pInfo ){
1597 if( pInfo->needToFreeIdxStr ){
1598 sqlite3_free(pInfo->idxStr);
1599 }
1600 sqliteFree(pInfo);
danielk1977be8a7832006-06-13 15:00:54 +00001601 }
drh9eff6162006-06-12 21:59:13 +00001602 }
1603 sqliteFree(pWInfo);
1604 }
1605}
1606
drh94a11212004-09-25 13:12:14 +00001607
1608/*
drhe3184742002-06-19 14:27:05 +00001609** Generate the beginning of the loop used for WHERE clause processing.
drhacf3b982005-01-03 01:27:18 +00001610** The return value is a pointer to an opaque structure that contains
drh75897232000-05-29 14:26:00 +00001611** information needed to terminate the loop. Later, the calling routine
danielk19774adee202004-05-08 08:23:19 +00001612** should invoke sqlite3WhereEnd() with the return value of this function
drh75897232000-05-29 14:26:00 +00001613** in order to complete the WHERE clause processing.
1614**
1615** If an error occurs, this routine returns NULL.
drhc27a1ce2002-06-14 20:58:45 +00001616**
1617** The basic idea is to do a nested loop, one loop for each table in
1618** the FROM clause of a select. (INSERT and UPDATE statements are the
1619** same as a SELECT with only a single table in the FROM clause.) For
1620** example, if the SQL is this:
1621**
1622** SELECT * FROM t1, t2, t3 WHERE ...;
1623**
1624** Then the code generated is conceptually like the following:
1625**
1626** foreach row1 in t1 do \ Code generated
danielk19774adee202004-05-08 08:23:19 +00001627** foreach row2 in t2 do |-- by sqlite3WhereBegin()
drhc27a1ce2002-06-14 20:58:45 +00001628** foreach row3 in t3 do /
1629** ...
1630** end \ Code generated
danielk19774adee202004-05-08 08:23:19 +00001631** end |-- by sqlite3WhereEnd()
drhc27a1ce2002-06-14 20:58:45 +00001632** end /
1633**
drh29dda4a2005-07-21 18:23:20 +00001634** Note that the loops might not be nested in the order in which they
1635** appear in the FROM clause if a different order is better able to make
drh51147ba2005-07-23 22:59:55 +00001636** use of indices. Note also that when the IN operator appears in
1637** the WHERE clause, it might result in additional nested loops for
1638** scanning through all values on the right-hand side of the IN.
drh29dda4a2005-07-21 18:23:20 +00001639**
drhc27a1ce2002-06-14 20:58:45 +00001640** There are Btree cursors associated with each table. t1 uses cursor
drh6a3ea0e2003-05-02 14:32:12 +00001641** number pTabList->a[0].iCursor. t2 uses the cursor pTabList->a[1].iCursor.
1642** And so forth. This routine generates code to open those VDBE cursors
danielk19774adee202004-05-08 08:23:19 +00001643** and sqlite3WhereEnd() generates the code to close them.
drhc27a1ce2002-06-14 20:58:45 +00001644**
drhe6f85e72004-12-25 01:03:13 +00001645** The code that sqlite3WhereBegin() generates leaves the cursors named
1646** in pTabList pointing at their appropriate entries. The [...] code
drhf0863fe2005-06-12 21:35:51 +00001647** can use OP_Column and OP_Rowid opcodes on these cursors to extract
drhe6f85e72004-12-25 01:03:13 +00001648** data from the various tables of the loop.
1649**
drhc27a1ce2002-06-14 20:58:45 +00001650** If the WHERE clause is empty, the foreach loops must each scan their
1651** entire tables. Thus a three-way join is an O(N^3) operation. But if
1652** the tables have indices and there are terms in the WHERE clause that
1653** refer to those indices, a complete table scan can be avoided and the
1654** code will run much faster. Most of the work of this routine is checking
1655** to see if there are indices that can be used to speed up the loop.
1656**
1657** Terms of the WHERE clause are also used to limit which rows actually
1658** make it to the "..." in the middle of the loop. After each "foreach",
1659** terms of the WHERE clause that use only terms in that loop and outer
1660** loops are evaluated and if false a jump is made around all subsequent
1661** inner loops (or around the "..." if the test occurs within the inner-
1662** most loop)
1663**
1664** OUTER JOINS
1665**
1666** An outer join of tables t1 and t2 is conceptally coded as follows:
1667**
1668** foreach row1 in t1 do
1669** flag = 0
1670** foreach row2 in t2 do
1671** start:
1672** ...
1673** flag = 1
1674** end
drhe3184742002-06-19 14:27:05 +00001675** if flag==0 then
1676** move the row2 cursor to a null row
1677** goto start
1678** fi
drhc27a1ce2002-06-14 20:58:45 +00001679** end
1680**
drhe3184742002-06-19 14:27:05 +00001681** ORDER BY CLAUSE PROCESSING
1682**
1683** *ppOrderBy is a pointer to the ORDER BY clause of a SELECT statement,
1684** if there is one. If there is no ORDER BY clause or if this routine
1685** is called from an UPDATE or DELETE statement, then ppOrderBy is NULL.
1686**
1687** If an index can be used so that the natural output order of the table
1688** scan is correct for the ORDER BY clause, then that index is used and
1689** *ppOrderBy is set to NULL. This is an optimization that prevents an
1690** unnecessary sort of the result set if an index appropriate for the
1691** ORDER BY clause already exists.
1692**
1693** If the where clause loops cannot be arranged to provide the correct
1694** output order, then the *ppOrderBy is unchanged.
drh75897232000-05-29 14:26:00 +00001695*/
danielk19774adee202004-05-08 08:23:19 +00001696WhereInfo *sqlite3WhereBegin(
danielk1977ed326d72004-11-16 15:50:19 +00001697 Parse *pParse, /* The parser context */
1698 SrcList *pTabList, /* A list of all tables to be scanned */
1699 Expr *pWhere, /* The WHERE clause */
drhf8db1bc2005-04-22 02:38:37 +00001700 ExprList **ppOrderBy /* An ORDER BY clause, or NULL */
drh75897232000-05-29 14:26:00 +00001701){
1702 int i; /* Loop counter */
1703 WhereInfo *pWInfo; /* Will become the return value of this function */
1704 Vdbe *v = pParse->pVdbe; /* The virtual database engine */
drhd4f5ee22003-07-16 00:54:31 +00001705 int brk, cont = 0; /* Addresses used during code generation */
drhfe05af82005-07-21 03:14:59 +00001706 Bitmask notReady; /* Cursors that are not yet positioned */
drh0aa74ed2005-07-16 13:33:20 +00001707 WhereTerm *pTerm; /* A single term in the WHERE clause */
1708 ExprMaskSet maskSet; /* The expression mask set */
drh0aa74ed2005-07-16 13:33:20 +00001709 WhereClause wc; /* The WHERE clause is divided into these terms */
drh9012bcb2004-12-19 00:11:35 +00001710 struct SrcList_item *pTabItem; /* A single entry from pTabList */
1711 WhereLevel *pLevel; /* A single level in the pWInfo list */
drh29dda4a2005-07-21 18:23:20 +00001712 int iFrom; /* First unused FROM clause element */
drh943af3c2005-07-29 19:43:58 +00001713 int andFlags; /* AND-ed combination of all wc.a[].flags */
drh75897232000-05-29 14:26:00 +00001714
drh29dda4a2005-07-21 18:23:20 +00001715 /* The number of tables in the FROM clause is limited by the number of
drh1398ad32005-01-19 23:24:50 +00001716 ** bits in a Bitmask
1717 */
drh29dda4a2005-07-21 18:23:20 +00001718 if( pTabList->nSrc>BMS ){
1719 sqlite3ErrorMsg(pParse, "at most %d tables in a join", BMS);
drh1398ad32005-01-19 23:24:50 +00001720 return 0;
1721 }
1722
drh83dcb1a2002-06-28 01:02:38 +00001723 /* Split the WHERE clause into separate subexpressions where each
drh29dda4a2005-07-21 18:23:20 +00001724 ** subexpression is separated by an AND operator.
drh83dcb1a2002-06-28 01:02:38 +00001725 */
drh6a3ea0e2003-05-02 14:32:12 +00001726 initMaskSet(&maskSet);
drhfe05af82005-07-21 03:14:59 +00001727 whereClauseInit(&wc, pParse);
drh6c30be82005-07-29 15:10:17 +00001728 whereSplit(&wc, pWhere, TK_AND);
drh1398ad32005-01-19 23:24:50 +00001729
drh75897232000-05-29 14:26:00 +00001730 /* Allocate and initialize the WhereInfo structure that will become the
1731 ** return value.
1732 */
drhad3cab52002-05-24 02:04:32 +00001733 pWInfo = sqliteMalloc( sizeof(WhereInfo) + pTabList->nSrc*sizeof(WhereLevel));
danielk19779e128002006-01-18 16:51:35 +00001734 if( sqlite3MallocFailed() ){
drhe23399f2005-07-22 00:31:39 +00001735 goto whereBeginNoMem;
drh75897232000-05-29 14:26:00 +00001736 }
danielk197770b6d572006-06-19 04:49:34 +00001737 pWInfo->nLevel = pTabList->nSrc;
drh75897232000-05-29 14:26:00 +00001738 pWInfo->pParse = pParse;
1739 pWInfo->pTabList = pTabList;
danielk19774adee202004-05-08 08:23:19 +00001740 pWInfo->iBreak = sqlite3VdbeMakeLabel(v);
drh08192d52002-04-30 19:20:28 +00001741
1742 /* Special case: a WHERE clause that is constant. Evaluate the
1743 ** expression and either jump over all of the code or fall thru.
1744 */
danielk19774adee202004-05-08 08:23:19 +00001745 if( pWhere && (pTabList->nSrc==0 || sqlite3ExprIsConstant(pWhere)) ){
1746 sqlite3ExprIfFalse(pParse, pWhere, pWInfo->iBreak, 1);
drhdf199a22002-06-14 22:38:41 +00001747 pWhere = 0;
drh08192d52002-04-30 19:20:28 +00001748 }
drh75897232000-05-29 14:26:00 +00001749
drh29dda4a2005-07-21 18:23:20 +00001750 /* Analyze all of the subexpressions. Note that exprAnalyze() might
1751 ** add new virtual terms onto the end of the WHERE clause. We do not
1752 ** want to analyze these virtual terms, so start analyzing at the end
drhb6fb62d2005-09-20 08:47:20 +00001753 ** and work forward so that the added virtual terms are never processed.
drh75897232000-05-29 14:26:00 +00001754 */
drh1398ad32005-01-19 23:24:50 +00001755 for(i=0; i<pTabList->nSrc; i++){
1756 createMask(&maskSet, pTabList->a[i].iCursor);
1757 }
drh6c30be82005-07-29 15:10:17 +00001758 exprAnalyzeAll(pTabList, &maskSet, &wc);
danielk19779e128002006-01-18 16:51:35 +00001759 if( sqlite3MallocFailed() ){
drh0bbaa1b2005-08-19 19:14:12 +00001760 goto whereBeginNoMem;
1761 }
drh75897232000-05-29 14:26:00 +00001762
drh29dda4a2005-07-21 18:23:20 +00001763 /* Chose the best index to use for each table in the FROM clause.
1764 **
drh51147ba2005-07-23 22:59:55 +00001765 ** This loop fills in the following fields:
1766 **
1767 ** pWInfo->a[].pIdx The index to use for this level of the loop.
1768 ** pWInfo->a[].flags WHERE_xxx flags associated with pIdx
1769 ** pWInfo->a[].nEq The number of == and IN constraints
1770 ** pWInfo->a[].iFrom When term of the FROM clause is being coded
1771 ** pWInfo->a[].iTabCur The VDBE cursor for the database table
1772 ** pWInfo->a[].iIdxCur The VDBE cursor for the index
1773 **
1774 ** This loop also figures out the nesting order of tables in the FROM
1775 ** clause.
drh75897232000-05-29 14:26:00 +00001776 */
drhfe05af82005-07-21 03:14:59 +00001777 notReady = ~(Bitmask)0;
drh9012bcb2004-12-19 00:11:35 +00001778 pTabItem = pTabList->a;
1779 pLevel = pWInfo->a;
drh943af3c2005-07-29 19:43:58 +00001780 andFlags = ~0;
drh3dec2232005-09-10 15:28:09 +00001781 TRACE(("*** Optimizer Start ***\n"));
drh29dda4a2005-07-21 18:23:20 +00001782 for(i=iFrom=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){
1783 Index *pIdx; /* Index for FROM table at pTabItem */
1784 int flags; /* Flags asssociated with pIdx */
drh51147ba2005-07-23 22:59:55 +00001785 int nEq; /* Number of == or IN constraints */
1786 double cost; /* The cost for pIdx */
drh29dda4a2005-07-21 18:23:20 +00001787 int j; /* For looping over FROM tables */
1788 Index *pBest = 0; /* The best index seen so far */
1789 int bestFlags = 0; /* Flags associated with pBest */
drh51147ba2005-07-23 22:59:55 +00001790 int bestNEq = 0; /* nEq associated with pBest */
drhb37df7b2005-10-13 02:09:49 +00001791 double lowestCost; /* Cost of the pBest */
drh02afc862006-01-20 18:10:57 +00001792 int bestJ = 0; /* The value of j */
drh29dda4a2005-07-21 18:23:20 +00001793 Bitmask m; /* Bitmask value for j or bestJ */
drh570b9352006-02-01 02:45:02 +00001794 int once = 0; /* True when first table is seen */
danielk197793626f42006-06-20 13:07:27 +00001795 sqlite3_index_info *pBestIndex = 0;
1796 sqlite3_index_info *pIndex = 0;
drh29dda4a2005-07-21 18:23:20 +00001797
drhb37df7b2005-10-13 02:09:49 +00001798 lowestCost = SQLITE_BIG_DBL;
drh29dda4a2005-07-21 18:23:20 +00001799 for(j=iFrom, pTabItem=&pTabList->a[j]; j<pTabList->nSrc; j++, pTabItem++){
drhdf26fd52006-06-06 11:45:54 +00001800 int doNotReorder; /* True if this table should not be reordered */
1801
1802 doNotReorder = (pTabItem->jointype & (JT_LEFT|JT_CROSS))!=0
1803 || (j>0 && (pTabItem[-1].jointype & (JT_LEFT|JT_CROSS))!=0);
1804 if( once && doNotReorder ) break;
drh29dda4a2005-07-21 18:23:20 +00001805 m = getMask(&maskSet, pTabItem->iCursor);
1806 if( (m & notReady)==0 ){
1807 if( j==iFrom ) iFrom++;
1808 continue;
1809 }
drh9eff6162006-06-12 21:59:13 +00001810 assert( pTabItem->pTab );
1811#ifndef SQLITE_OMIT_VIRTUALTABLE
drh4cbdda92006-06-14 19:00:20 +00001812 if( IsVirtual(pTabItem->pTab) ){
drh9eff6162006-06-12 21:59:13 +00001813 cost = bestVirtualIndex(pParse, &wc, pTabItem, notReady,
1814 ppOrderBy ? *ppOrderBy : 0, i==0,
danielk197793626f42006-06-20 13:07:27 +00001815 &pIndex);
drh9eff6162006-06-12 21:59:13 +00001816 flags = WHERE_VIRTUALTABLE;
danielk197793626f42006-06-20 13:07:27 +00001817 if( pIndex && pIndex->orderByConsumed ){
drh1a90e092006-06-14 22:07:10 +00001818 flags = WHERE_VIRTUALTABLE | WHERE_ORDERBY;
1819 }
drh9eff6162006-06-12 21:59:13 +00001820 pIdx = 0;
1821 nEq = 0;
1822 }else
1823#endif
1824 {
1825 cost = bestIndex(pParse, &wc, pTabItem, notReady,
1826 (i==0 && ppOrderBy) ? *ppOrderBy : 0,
1827 &pIdx, &flags, &nEq);
1828 }
drh51147ba2005-07-23 22:59:55 +00001829 if( cost<lowestCost ){
drh570b9352006-02-01 02:45:02 +00001830 once = 1;
drh51147ba2005-07-23 22:59:55 +00001831 lowestCost = cost;
drh29dda4a2005-07-21 18:23:20 +00001832 pBest = pIdx;
1833 bestFlags = flags;
drh51147ba2005-07-23 22:59:55 +00001834 bestNEq = nEq;
drh29dda4a2005-07-21 18:23:20 +00001835 bestJ = j;
danielk197793626f42006-06-20 13:07:27 +00001836#ifndef SQLITE_OMIT_VIRTUALTABLE
1837 sqliteFree(pBestIndex);
1838 pBestIndex = pIndex;
1839 pIndex = 0;
1840 }else{
1841 sqliteFree(pIndex);
1842 pIndex = 0;
1843#endif
drh29dda4a2005-07-21 18:23:20 +00001844 }
drhdf26fd52006-06-06 11:45:54 +00001845 if( doNotReorder ) break;
drh29dda4a2005-07-21 18:23:20 +00001846 }
drh3dec2232005-09-10 15:28:09 +00001847 TRACE(("*** Optimizer choose table %d for loop %d\n", bestJ,
1848 pLevel-pWInfo->a));
drh943af3c2005-07-29 19:43:58 +00001849 if( (bestFlags & WHERE_ORDERBY)!=0 ){
drhfe05af82005-07-21 03:14:59 +00001850 *ppOrderBy = 0;
drhc4a3c772001-04-04 11:48:57 +00001851 }
drh943af3c2005-07-29 19:43:58 +00001852 andFlags &= bestFlags;
drh29dda4a2005-07-21 18:23:20 +00001853 pLevel->flags = bestFlags;
drhfe05af82005-07-21 03:14:59 +00001854 pLevel->pIdx = pBest;
drh51147ba2005-07-23 22:59:55 +00001855 pLevel->nEq = bestNEq;
drhe23399f2005-07-22 00:31:39 +00001856 pLevel->aInLoop = 0;
1857 pLevel->nIn = 0;
danielk197793626f42006-06-20 13:07:27 +00001858 pLevel->pIdxInfo = pBestIndex;
drhfe05af82005-07-21 03:14:59 +00001859 if( pBest ){
drh9012bcb2004-12-19 00:11:35 +00001860 pLevel->iIdxCur = pParse->nTab++;
drhfe05af82005-07-21 03:14:59 +00001861 }else{
1862 pLevel->iIdxCur = -1;
drh6b563442001-11-07 16:48:26 +00001863 }
drh29dda4a2005-07-21 18:23:20 +00001864 notReady &= ~getMask(&maskSet, pTabList->a[bestJ].iCursor);
1865 pLevel->iFrom = bestJ;
drh75897232000-05-29 14:26:00 +00001866 }
drh3dec2232005-09-10 15:28:09 +00001867 TRACE(("*** Optimizer Finished ***\n"));
drh75897232000-05-29 14:26:00 +00001868
drh943af3c2005-07-29 19:43:58 +00001869 /* If the total query only selects a single row, then the ORDER BY
1870 ** clause is irrelevant.
1871 */
1872 if( (andFlags & WHERE_UNIQUE)!=0 && ppOrderBy ){
1873 *ppOrderBy = 0;
1874 }
1875
drh9012bcb2004-12-19 00:11:35 +00001876 /* Open all tables in the pTabList and any indices selected for
1877 ** searching those tables.
1878 */
1879 sqlite3CodeVerifySchema(pParse, -1); /* Insert the cookie verifier Goto */
1880 pLevel = pWInfo->a;
drh29dda4a2005-07-21 18:23:20 +00001881 for(i=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){
danielk1977da184232006-01-05 11:34:32 +00001882 Table *pTab; /* Table to open */
1883 Index *pIx; /* Index used to access pTab (if any) */
1884 int iDb; /* Index of database containing table/index */
drh9012bcb2004-12-19 00:11:35 +00001885 int iIdxCur = pLevel->iIdxCur;
1886
drhecc92422005-09-10 16:46:12 +00001887#ifndef SQLITE_OMIT_EXPLAIN
1888 if( pParse->explain==2 ){
1889 char *zMsg;
1890 struct SrcList_item *pItem = &pTabList->a[pLevel->iFrom];
1891 zMsg = sqlite3MPrintf("TABLE %s", pItem->zName);
1892 if( pItem->zAlias ){
1893 zMsg = sqlite3MPrintf("%z AS %s", zMsg, pItem->zAlias);
1894 }
1895 if( (pIx = pLevel->pIdx)!=0 ){
1896 zMsg = sqlite3MPrintf("%z WITH INDEX %s", zMsg, pIx->zName);
drh36d64932005-11-21 12:46:27 +00001897 }else if( pLevel->flags & (WHERE_ROWID_EQ|WHERE_ROWID_RANGE) ){
drh32daab62005-11-21 12:48:24 +00001898 zMsg = sqlite3MPrintf("%z USING PRIMARY KEY", zMsg);
drhecc92422005-09-10 16:46:12 +00001899 }
drh9eff6162006-06-12 21:59:13 +00001900#ifndef SQLITE_OMIT_VIRTUALTABLE
1901 else if( pLevel->pIdxInfo ){
drh4be8b512006-06-13 23:51:34 +00001902 sqlite3_index_info *pIdxInfo = pLevel->pIdxInfo;
danielk197765fd59f2006-06-24 11:51:33 +00001903 zMsg = sqlite3MPrintf("%z VIRTUAL TABLE INDEX %d:%s", zMsg,
drh4be8b512006-06-13 23:51:34 +00001904 pIdxInfo->idxNum, pIdxInfo->idxStr);
drh9eff6162006-06-12 21:59:13 +00001905 }
1906#endif
drhe2b39092006-04-21 09:38:36 +00001907 if( pLevel->flags & WHERE_ORDERBY ){
1908 zMsg = sqlite3MPrintf("%z ORDER BY", zMsg);
1909 }
drhecc92422005-09-10 16:46:12 +00001910 sqlite3VdbeOp3(v, OP_Explain, i, pLevel->iFrom, zMsg, P3_DYNAMIC);
1911 }
1912#endif /* SQLITE_OMIT_EXPLAIN */
drh29dda4a2005-07-21 18:23:20 +00001913 pTabItem = &pTabList->a[pLevel->iFrom];
drh9012bcb2004-12-19 00:11:35 +00001914 pTab = pTabItem->pTab;
danielk1977da184232006-01-05 11:34:32 +00001915 iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
drhb9bb7c12006-06-11 23:41:55 +00001916 if( pTab->isEphem || pTab->pSelect ) continue;
drh9eff6162006-06-12 21:59:13 +00001917#ifndef SQLITE_OMIT_VIRTUALTABLE
1918 if( pLevel->pIdxInfo ){
danielk197793626f42006-06-20 13:07:27 +00001919 int iCur = pTabItem->iCursor;
1920 sqlite3VdbeOp3(v, OP_VOpen, iCur, 0, (const char*)pTab->pVtab, P3_VTAB);
drh9eff6162006-06-12 21:59:13 +00001921 }else
1922#endif
drhfe05af82005-07-21 03:14:59 +00001923 if( (pLevel->flags & WHERE_IDX_ONLY)==0 ){
danielk1977c00da102006-01-07 13:21:04 +00001924 sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, OP_OpenRead);
danielk19779792eef2006-01-13 15:58:43 +00001925 if( pTab->nCol<(sizeof(Bitmask)*8) ){
1926 Bitmask b = pTabItem->colUsed;
1927 int n = 0;
drh74161702006-02-24 02:53:49 +00001928 for(; b; b=b>>1, n++){}
danielk19779792eef2006-01-13 15:58:43 +00001929 sqlite3VdbeChangeP2(v, sqlite3VdbeCurrentAddr(v)-1, n);
1930 assert( n<=pTab->nCol );
1931 }
danielk1977c00da102006-01-07 13:21:04 +00001932 }else{
1933 sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
drh9012bcb2004-12-19 00:11:35 +00001934 }
1935 pLevel->iTabCur = pTabItem->iCursor;
1936 if( (pIx = pLevel->pIdx)!=0 ){
danielk1977b3bf5562006-01-10 17:58:23 +00001937 KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIx);
danielk1977da184232006-01-05 11:34:32 +00001938 assert( pIx->pSchema==pTab->pSchema );
1939 sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
drh29dda4a2005-07-21 18:23:20 +00001940 VdbeComment((v, "# %s", pIx->zName));
drh9012bcb2004-12-19 00:11:35 +00001941 sqlite3VdbeOp3(v, OP_OpenRead, iIdxCur, pIx->tnum,
danielk1977b3bf5562006-01-10 17:58:23 +00001942 (char*)pKey, P3_KEYINFO_HANDOFF);
drh9012bcb2004-12-19 00:11:35 +00001943 }
drhfe05af82005-07-21 03:14:59 +00001944 if( (pLevel->flags & WHERE_IDX_ONLY)!=0 ){
drh9012bcb2004-12-19 00:11:35 +00001945 sqlite3VdbeAddOp(v, OP_SetNumColumns, iIdxCur, pIx->nColumn+1);
1946 }
danielk1977da184232006-01-05 11:34:32 +00001947 sqlite3CodeVerifySchema(pParse, iDb);
drh9012bcb2004-12-19 00:11:35 +00001948 }
1949 pWInfo->iTop = sqlite3VdbeCurrentAddr(v);
1950
drh29dda4a2005-07-21 18:23:20 +00001951 /* Generate the code to do the search. Each iteration of the for
1952 ** loop below generates code for a single nested loop of the VM
1953 ** program.
drh75897232000-05-29 14:26:00 +00001954 */
drhfe05af82005-07-21 03:14:59 +00001955 notReady = ~(Bitmask)0;
drh29dda4a2005-07-21 18:23:20 +00001956 for(i=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){
drhfe05af82005-07-21 03:14:59 +00001957 int j;
drh9012bcb2004-12-19 00:11:35 +00001958 int iCur = pTabItem->iCursor; /* The VDBE cursor for the table */
1959 Index *pIdx; /* The index we will be using */
1960 int iIdxCur; /* The VDBE cursor for the index */
1961 int omitTable; /* True if we use the index only */
drh29dda4a2005-07-21 18:23:20 +00001962 int bRev; /* True if we need to scan in reverse order */
drh9012bcb2004-12-19 00:11:35 +00001963
drh29dda4a2005-07-21 18:23:20 +00001964 pTabItem = &pTabList->a[pLevel->iFrom];
1965 iCur = pTabItem->iCursor;
drh9012bcb2004-12-19 00:11:35 +00001966 pIdx = pLevel->pIdx;
1967 iIdxCur = pLevel->iIdxCur;
drh29dda4a2005-07-21 18:23:20 +00001968 bRev = (pLevel->flags & WHERE_REVERSE)!=0;
drhfe05af82005-07-21 03:14:59 +00001969 omitTable = (pLevel->flags & WHERE_IDX_ONLY)!=0;
drh75897232000-05-29 14:26:00 +00001970
drh29dda4a2005-07-21 18:23:20 +00001971 /* Create labels for the "break" and "continue" instructions
1972 ** for the current loop. Jump to brk to break out of a loop.
1973 ** Jump to cont to go immediately to the next iteration of the
1974 ** loop.
1975 */
1976 brk = pLevel->brk = sqlite3VdbeMakeLabel(v);
1977 cont = pLevel->cont = sqlite3VdbeMakeLabel(v);
1978
drhad2d8302002-05-24 20:31:36 +00001979 /* If this is the right table of a LEFT OUTER JOIN, allocate and
drh174b6192002-12-03 02:22:52 +00001980 ** initialize a memory cell that records if this table matches any
drhc27a1ce2002-06-14 20:58:45 +00001981 ** row of the left table of the join.
drhad2d8302002-05-24 20:31:36 +00001982 */
drh29dda4a2005-07-21 18:23:20 +00001983 if( pLevel->iFrom>0 && (pTabItem[-1].jointype & JT_LEFT)!=0 ){
drhad2d8302002-05-24 20:31:36 +00001984 if( !pParse->nMem ) pParse->nMem++;
1985 pLevel->iLeftJoin = pParse->nMem++;
drhd654be82005-09-20 17:42:23 +00001986 sqlite3VdbeAddOp(v, OP_MemInt, 0, pLevel->iLeftJoin);
drhad6d9462004-09-19 02:15:24 +00001987 VdbeComment((v, "# init LEFT JOIN no-match flag"));
drhad2d8302002-05-24 20:31:36 +00001988 }
1989
drh9eff6162006-06-12 21:59:13 +00001990#ifndef SQLITE_OMIT_VIRTUALTABLE
1991 if( pLevel->pIdxInfo ){
drh7f375902006-06-13 17:38:59 +00001992 /* Case 0: The table is a virtual-table. Use the VFilter and VNext
1993 ** to access the data.
1994 */
danielk197793626f42006-06-20 13:07:27 +00001995 int ii;
drh9eff6162006-06-12 21:59:13 +00001996 sqlite3_index_info *pIdxInfo = pLevel->pIdxInfo;
drh4be8b512006-06-13 23:51:34 +00001997 int nConstraint = pIdxInfo->nConstraint;
1998 struct sqlite3_index_constraint_usage *aUsage =
1999 pIdxInfo->aConstraintUsage;
2000 const struct sqlite3_index_constraint *aConstraint =
2001 pIdxInfo->aConstraint;
2002
danielk197793626f42006-06-20 13:07:27 +00002003 for(ii=1; ii<=nConstraint; ii++){
drh9eff6162006-06-12 21:59:13 +00002004 int j;
drh4be8b512006-06-13 23:51:34 +00002005 for(j=0; j<nConstraint; j++){
danielk197793626f42006-06-20 13:07:27 +00002006 if( aUsage[j].argvIndex==ii ){
drh4be8b512006-06-13 23:51:34 +00002007 int k = aConstraint[j].iTermOffset;
2008 sqlite3ExprCode(pParse, wc.a[k].pExpr->pRight);
drh9eff6162006-06-12 21:59:13 +00002009 break;
2010 }
2011 }
drh4be8b512006-06-13 23:51:34 +00002012 if( j==nConstraint ) break;
drh9eff6162006-06-12 21:59:13 +00002013 }
danielk197793626f42006-06-20 13:07:27 +00002014 sqlite3VdbeAddOp(v, OP_Integer, ii-1, 0);
drh4be8b512006-06-13 23:51:34 +00002015 sqlite3VdbeAddOp(v, OP_Integer, pIdxInfo->idxNum, 0);
2016 sqlite3VdbeOp3(v, OP_VFilter, iCur, brk, pIdxInfo->idxStr,
2017 pIdxInfo->needToFreeIdxStr ? P3_MPRINTF : P3_STATIC);
2018 pIdxInfo->needToFreeIdxStr = 0;
danielk197793626f42006-06-20 13:07:27 +00002019 for(ii=0; ii<pIdxInfo->nConstraint; ii++){
2020 if( pIdxInfo->aConstraintUsage[ii].omit ){
2021 disableTerm(pLevel, &wc.a[ii]);
drh9eff6162006-06-12 21:59:13 +00002022 }
2023 }
2024 pLevel->op = OP_VNext;
drha967e882006-06-13 01:04:52 +00002025 pLevel->p1 = iCur;
2026 pLevel->p2 = sqlite3VdbeCurrentAddr(v);
drh9eff6162006-06-12 21:59:13 +00002027 }else
2028#endif /* SQLITE_OMIT_VIRTUALTABLE */
2029
drhfe05af82005-07-21 03:14:59 +00002030 if( pLevel->flags & WHERE_ROWID_EQ ){
drh8aff1012001-12-22 14:49:24 +00002031 /* Case 1: We can directly reference a single row using an
drhc27a1ce2002-06-14 20:58:45 +00002032 ** equality comparison against the ROWID field. Or
2033 ** we reference multiple rows using a "rowid IN (...)"
2034 ** construct.
drhc4a3c772001-04-04 11:48:57 +00002035 */
drhfe05af82005-07-21 03:14:59 +00002036 pTerm = findTerm(&wc, iCur, -1, notReady, WO_EQ|WO_IN, 0);
2037 assert( pTerm!=0 );
drh0fcef5e2005-07-19 17:38:22 +00002038 assert( pTerm->pExpr!=0 );
2039 assert( pTerm->leftCursor==iCur );
drh9012bcb2004-12-19 00:11:35 +00002040 assert( omitTable==0 );
drh94a11212004-09-25 13:12:14 +00002041 codeEqualityTerm(pParse, pTerm, brk, pLevel);
danielk19774adee202004-05-08 08:23:19 +00002042 sqlite3VdbeAddOp(v, OP_MustBeInt, 1, brk);
danielk19774adee202004-05-08 08:23:19 +00002043 sqlite3VdbeAddOp(v, OP_NotExists, iCur, brk);
tpoindex7a9b1612005-01-03 18:13:18 +00002044 VdbeComment((v, "pk"));
drh6b563442001-11-07 16:48:26 +00002045 pLevel->op = OP_Noop;
drhfe05af82005-07-21 03:14:59 +00002046 }else if( pLevel->flags & WHERE_ROWID_RANGE ){
drh51147ba2005-07-23 22:59:55 +00002047 /* Case 2: We have an inequality comparison against the ROWID field.
drh8aff1012001-12-22 14:49:24 +00002048 */
2049 int testOp = OP_Noop;
2050 int start;
drhfe05af82005-07-21 03:14:59 +00002051 WhereTerm *pStart, *pEnd;
drh8aff1012001-12-22 14:49:24 +00002052
drh9012bcb2004-12-19 00:11:35 +00002053 assert( omitTable==0 );
drha6110402005-07-28 20:51:19 +00002054 pStart = findTerm(&wc, iCur, -1, notReady, WO_GT|WO_GE, 0);
2055 pEnd = findTerm(&wc, iCur, -1, notReady, WO_LT|WO_LE, 0);
drhfe05af82005-07-21 03:14:59 +00002056 if( bRev ){
2057 pTerm = pStart;
2058 pStart = pEnd;
2059 pEnd = pTerm;
2060 }
2061 if( pStart ){
drh94a11212004-09-25 13:12:14 +00002062 Expr *pX;
drhfe05af82005-07-21 03:14:59 +00002063 pX = pStart->pExpr;
drh94a11212004-09-25 13:12:14 +00002064 assert( pX!=0 );
drhfe05af82005-07-21 03:14:59 +00002065 assert( pStart->leftCursor==iCur );
drh94a11212004-09-25 13:12:14 +00002066 sqlite3ExprCode(pParse, pX->pRight);
danielk1977d0a69322005-02-02 01:10:44 +00002067 sqlite3VdbeAddOp(v, OP_ForceInt, pX->op==TK_LE || pX->op==TK_GT, brk);
drhb6c29892004-11-22 19:12:19 +00002068 sqlite3VdbeAddOp(v, bRev ? OP_MoveLt : OP_MoveGe, iCur, brk);
tpoindex7a9b1612005-01-03 18:13:18 +00002069 VdbeComment((v, "pk"));
drhfe05af82005-07-21 03:14:59 +00002070 disableTerm(pLevel, pStart);
drh8aff1012001-12-22 14:49:24 +00002071 }else{
drhb6c29892004-11-22 19:12:19 +00002072 sqlite3VdbeAddOp(v, bRev ? OP_Last : OP_Rewind, iCur, brk);
drh8aff1012001-12-22 14:49:24 +00002073 }
drhfe05af82005-07-21 03:14:59 +00002074 if( pEnd ){
drh94a11212004-09-25 13:12:14 +00002075 Expr *pX;
drhfe05af82005-07-21 03:14:59 +00002076 pX = pEnd->pExpr;
drh94a11212004-09-25 13:12:14 +00002077 assert( pX!=0 );
drhfe05af82005-07-21 03:14:59 +00002078 assert( pEnd->leftCursor==iCur );
drh94a11212004-09-25 13:12:14 +00002079 sqlite3ExprCode(pParse, pX->pRight);
drh8aff1012001-12-22 14:49:24 +00002080 pLevel->iMem = pParse->nMem++;
danielk19774adee202004-05-08 08:23:19 +00002081 sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
drh94a11212004-09-25 13:12:14 +00002082 if( pX->op==TK_LT || pX->op==TK_GT ){
drhb6c29892004-11-22 19:12:19 +00002083 testOp = bRev ? OP_Le : OP_Ge;
drh8aff1012001-12-22 14:49:24 +00002084 }else{
drhb6c29892004-11-22 19:12:19 +00002085 testOp = bRev ? OP_Lt : OP_Gt;
drh8aff1012001-12-22 14:49:24 +00002086 }
drhfe05af82005-07-21 03:14:59 +00002087 disableTerm(pLevel, pEnd);
drh8aff1012001-12-22 14:49:24 +00002088 }
danielk19774adee202004-05-08 08:23:19 +00002089 start = sqlite3VdbeCurrentAddr(v);
drhb6c29892004-11-22 19:12:19 +00002090 pLevel->op = bRev ? OP_Prev : OP_Next;
drh6a3ea0e2003-05-02 14:32:12 +00002091 pLevel->p1 = iCur;
drh8aff1012001-12-22 14:49:24 +00002092 pLevel->p2 = start;
2093 if( testOp!=OP_Noop ){
drhf0863fe2005-06-12 21:35:51 +00002094 sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
danielk19774adee202004-05-08 08:23:19 +00002095 sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
drh8a512562005-11-14 22:29:05 +00002096 sqlite3VdbeAddOp(v, testOp, SQLITE_AFF_NUMERIC, brk);
drh8aff1012001-12-22 14:49:24 +00002097 }
drhfe05af82005-07-21 03:14:59 +00002098 }else if( pLevel->flags & WHERE_COLUMN_RANGE ){
drh51147ba2005-07-23 22:59:55 +00002099 /* Case 3: The WHERE clause term that refers to the right-most
drhc27a1ce2002-06-14 20:58:45 +00002100 ** column of the index is an inequality. For example, if
2101 ** the index is on (x,y,z) and the WHERE clause is of the
2102 ** form "x=5 AND y<10" then this case is used. Only the
2103 ** right-most column can be an inequality - the rest must
drh51147ba2005-07-23 22:59:55 +00002104 ** use the "==" and "IN" operators.
drhe3184742002-06-19 14:27:05 +00002105 **
2106 ** This case is also used when there are no WHERE clause
2107 ** constraints but an index is selected anyway, in order
2108 ** to force the output order to conform to an ORDER BY.
drh487ab3c2001-11-08 00:45:21 +00002109 */
drh487ab3c2001-11-08 00:45:21 +00002110 int start;
drh51147ba2005-07-23 22:59:55 +00002111 int nEq = pLevel->nEq;
drh85eeb692005-12-21 03:16:42 +00002112 int topEq=0; /* True if top limit uses ==. False is strictly < */
2113 int btmEq=0; /* True if btm limit uses ==. False if strictly > */
2114 int topOp, btmOp; /* Operators for the top and bottom search bounds */
drh487ab3c2001-11-08 00:45:21 +00002115 int testOp;
drh0b2f3162005-12-21 18:36:45 +00002116 int nNotNull; /* Number of rows of index that must be non-NULL */
drhfe05af82005-07-21 03:14:59 +00002117 int topLimit = (pLevel->flags & WHERE_TOP_LIMIT)!=0;
2118 int btmLimit = (pLevel->flags & WHERE_BTM_LIMIT)!=0;
drh487ab3c2001-11-08 00:45:21 +00002119
drh51147ba2005-07-23 22:59:55 +00002120 /* Generate code to evaluate all constraint terms using == or IN
2121 ** and level the values of those terms on the stack.
drh487ab3c2001-11-08 00:45:21 +00002122 */
drh51147ba2005-07-23 22:59:55 +00002123 codeAllEqualityTerms(pParse, pLevel, &wc, notReady, brk);
drh487ab3c2001-11-08 00:45:21 +00002124
drhc27a1ce2002-06-14 20:58:45 +00002125 /* Duplicate the equality term values because they will all be
drh487ab3c2001-11-08 00:45:21 +00002126 ** used twice: once to make the termination key and once to make the
2127 ** start key.
2128 */
drh51147ba2005-07-23 22:59:55 +00002129 for(j=0; j<nEq; j++){
2130 sqlite3VdbeAddOp(v, OP_Dup, nEq-1, 0);
drh487ab3c2001-11-08 00:45:21 +00002131 }
2132
drh85eeb692005-12-21 03:16:42 +00002133 /* Figure out what comparison operators to use for top and bottom
2134 ** search bounds. For an ascending index, the bottom bound is a > or >=
2135 ** operator and the top bound is a < or <= operator. For a descending
2136 ** index the operators are reversed.
2137 */
drh0b2f3162005-12-21 18:36:45 +00002138 nNotNull = nEq + topLimit;
danielk1977b3bf5562006-01-10 17:58:23 +00002139 if( pIdx->aSortOrder[nEq]==SQLITE_SO_ASC ){
drh85eeb692005-12-21 03:16:42 +00002140 topOp = WO_LT|WO_LE;
2141 btmOp = WO_GT|WO_GE;
2142 }else{
2143 topOp = WO_GT|WO_GE;
2144 btmOp = WO_LT|WO_LE;
2145 SWAP(int, topLimit, btmLimit);
2146 }
2147
drh487ab3c2001-11-08 00:45:21 +00002148 /* Generate the termination key. This is the key value that
2149 ** will end the search. There is no termination key if there
drhc27a1ce2002-06-14 20:58:45 +00002150 ** are no equality terms and no "X<..." term.
drhc045ec52002-12-04 20:01:06 +00002151 **
2152 ** 2002-Dec-04: On a reverse-order scan, the so-called "termination"
2153 ** key computed here really ends up being the start key.
drh487ab3c2001-11-08 00:45:21 +00002154 */
drhfe05af82005-07-21 03:14:59 +00002155 if( topLimit ){
drhe8b97272005-07-19 22:22:12 +00002156 Expr *pX;
drhfe05af82005-07-21 03:14:59 +00002157 int k = pIdx->aiColumn[j];
drh85eeb692005-12-21 03:16:42 +00002158 pTerm = findTerm(&wc, iCur, k, notReady, topOp, pIdx);
drhe8b97272005-07-19 22:22:12 +00002159 assert( pTerm!=0 );
2160 pX = pTerm->pExpr;
2161 assert( (pTerm->flags & TERM_CODED)==0 );
2162 sqlite3ExprCode(pParse, pX->pRight);
drhb52076c2006-01-23 13:22:09 +00002163 topEq = pTerm->eOperator & (WO_LE|WO_GE);
drhe8b97272005-07-19 22:22:12 +00002164 disableTerm(pLevel, pTerm);
drh487ab3c2001-11-08 00:45:21 +00002165 testOp = OP_IdxGE;
2166 }else{
drh51147ba2005-07-23 22:59:55 +00002167 testOp = nEq>0 ? OP_IdxGE : OP_Noop;
drh85eeb692005-12-21 03:16:42 +00002168 topEq = 1;
drh487ab3c2001-11-08 00:45:21 +00002169 }
2170 if( testOp!=OP_Noop ){
drh51147ba2005-07-23 22:59:55 +00002171 int nCol = nEq + topLimit;
drh487ab3c2001-11-08 00:45:21 +00002172 pLevel->iMem = pParse->nMem++;
danielk1977327bd592006-01-13 13:01:19 +00002173 buildIndexProbe(v, nCol, nEq, brk, pIdx);
drhfe05af82005-07-21 03:14:59 +00002174 if( bRev ){
drh85eeb692005-12-21 03:16:42 +00002175 int op = topEq ? OP_MoveLe : OP_MoveLt;
drh9012bcb2004-12-19 00:11:35 +00002176 sqlite3VdbeAddOp(v, op, iIdxCur, brk);
drhc045ec52002-12-04 20:01:06 +00002177 }else{
danielk19774adee202004-05-08 08:23:19 +00002178 sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
drhc045ec52002-12-04 20:01:06 +00002179 }
drhfe05af82005-07-21 03:14:59 +00002180 }else if( bRev ){
drh9012bcb2004-12-19 00:11:35 +00002181 sqlite3VdbeAddOp(v, OP_Last, iIdxCur, brk);
drh487ab3c2001-11-08 00:45:21 +00002182 }
2183
2184 /* Generate the start key. This is the key that defines the lower
drhc27a1ce2002-06-14 20:58:45 +00002185 ** bound on the search. There is no start key if there are no
2186 ** equality terms and if there is no "X>..." term. In
drh487ab3c2001-11-08 00:45:21 +00002187 ** that case, generate a "Rewind" instruction in place of the
2188 ** start key search.
drhc045ec52002-12-04 20:01:06 +00002189 **
2190 ** 2002-Dec-04: In the case of a reverse-order search, the so-called
2191 ** "start" key really ends up being used as the termination key.
drh487ab3c2001-11-08 00:45:21 +00002192 */
drhfe05af82005-07-21 03:14:59 +00002193 if( btmLimit ){
drhe8b97272005-07-19 22:22:12 +00002194 Expr *pX;
drhfe05af82005-07-21 03:14:59 +00002195 int k = pIdx->aiColumn[j];
drh85eeb692005-12-21 03:16:42 +00002196 pTerm = findTerm(&wc, iCur, k, notReady, btmOp, pIdx);
drhe8b97272005-07-19 22:22:12 +00002197 assert( pTerm!=0 );
2198 pX = pTerm->pExpr;
2199 assert( (pTerm->flags & TERM_CODED)==0 );
2200 sqlite3ExprCode(pParse, pX->pRight);
drhb52076c2006-01-23 13:22:09 +00002201 btmEq = pTerm->eOperator & (WO_LE|WO_GE);
drhe8b97272005-07-19 22:22:12 +00002202 disableTerm(pLevel, pTerm);
drh7900ead2001-11-12 13:51:43 +00002203 }else{
drh85eeb692005-12-21 03:16:42 +00002204 btmEq = 1;
drh487ab3c2001-11-08 00:45:21 +00002205 }
drh51147ba2005-07-23 22:59:55 +00002206 if( nEq>0 || btmLimit ){
2207 int nCol = nEq + btmLimit;
danielk1977327bd592006-01-13 13:01:19 +00002208 buildIndexProbe(v, nCol, 0, brk, pIdx);
drhfe05af82005-07-21 03:14:59 +00002209 if( bRev ){
drhc045ec52002-12-04 20:01:06 +00002210 pLevel->iMem = pParse->nMem++;
danielk19774adee202004-05-08 08:23:19 +00002211 sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
drhc045ec52002-12-04 20:01:06 +00002212 testOp = OP_IdxLT;
2213 }else{
drh85eeb692005-12-21 03:16:42 +00002214 int op = btmEq ? OP_MoveGe : OP_MoveGt;
drh9012bcb2004-12-19 00:11:35 +00002215 sqlite3VdbeAddOp(v, op, iIdxCur, brk);
drhc045ec52002-12-04 20:01:06 +00002216 }
drhfe05af82005-07-21 03:14:59 +00002217 }else if( bRev ){
drhc045ec52002-12-04 20:01:06 +00002218 testOp = OP_Noop;
drh487ab3c2001-11-08 00:45:21 +00002219 }else{
drh9012bcb2004-12-19 00:11:35 +00002220 sqlite3VdbeAddOp(v, OP_Rewind, iIdxCur, brk);
drh487ab3c2001-11-08 00:45:21 +00002221 }
2222
2223 /* Generate the the top of the loop. If there is a termination
2224 ** key we have to test for that key and abort at the top of the
2225 ** loop.
2226 */
danielk19774adee202004-05-08 08:23:19 +00002227 start = sqlite3VdbeCurrentAddr(v);
drh487ab3c2001-11-08 00:45:21 +00002228 if( testOp!=OP_Noop ){
danielk19774adee202004-05-08 08:23:19 +00002229 sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
drh9012bcb2004-12-19 00:11:35 +00002230 sqlite3VdbeAddOp(v, testOp, iIdxCur, brk);
drh85eeb692005-12-21 03:16:42 +00002231 if( (topEq && !bRev) || (!btmEq && bRev) ){
danielk19773d1bfea2004-05-14 11:00:53 +00002232 sqlite3VdbeChangeP3(v, -1, "+", P3_STATIC);
2233 }
drh487ab3c2001-11-08 00:45:21 +00002234 }
drh9012bcb2004-12-19 00:11:35 +00002235 sqlite3VdbeAddOp(v, OP_RowKey, iIdxCur, 0);
drh0b2f3162005-12-21 18:36:45 +00002236 sqlite3VdbeAddOp(v, OP_IdxIsNull, nNotNull, cont);
drhe6f85e72004-12-25 01:03:13 +00002237 if( !omitTable ){
drhf0863fe2005-06-12 21:35:51 +00002238 sqlite3VdbeAddOp(v, OP_IdxRowid, iIdxCur, 0);
drhe6f85e72004-12-25 01:03:13 +00002239 sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
drh487ab3c2001-11-08 00:45:21 +00002240 }
2241
2242 /* Record the instruction used to terminate the loop.
2243 */
drhfe05af82005-07-21 03:14:59 +00002244 pLevel->op = bRev ? OP_Prev : OP_Next;
drh9012bcb2004-12-19 00:11:35 +00002245 pLevel->p1 = iIdxCur;
drh487ab3c2001-11-08 00:45:21 +00002246 pLevel->p2 = start;
drh51147ba2005-07-23 22:59:55 +00002247 }else if( pLevel->flags & WHERE_COLUMN_EQ ){
2248 /* Case 4: There is an index and all terms of the WHERE clause that
2249 ** refer to the index using the "==" or "IN" operators.
2250 */
2251 int start;
2252 int nEq = pLevel->nEq;
2253
2254 /* Generate code to evaluate all constraint terms using == or IN
drh8b3d9902005-08-19 00:14:42 +00002255 ** and leave the values of those terms on the stack.
drh51147ba2005-07-23 22:59:55 +00002256 */
2257 codeAllEqualityTerms(pParse, pLevel, &wc, notReady, brk);
2258
2259 /* Generate a single key that will be used to both start and terminate
2260 ** the search
2261 */
danielk1977327bd592006-01-13 13:01:19 +00002262 buildIndexProbe(v, nEq, 0, brk, pIdx);
drh51147ba2005-07-23 22:59:55 +00002263 sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 0);
2264
2265 /* Generate code (1) to move to the first matching element of the table.
2266 ** Then generate code (2) that jumps to "brk" after the cursor is past
2267 ** the last matching element of the table. The code (1) is executed
2268 ** once to initialize the search, the code (2) is executed before each
2269 ** iteration of the scan to see if the scan has finished. */
2270 if( bRev ){
2271 /* Scan in reverse order */
2272 sqlite3VdbeAddOp(v, OP_MoveLe, iIdxCur, brk);
2273 start = sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
2274 sqlite3VdbeAddOp(v, OP_IdxLT, iIdxCur, brk);
2275 pLevel->op = OP_Prev;
2276 }else{
2277 /* Scan in the forward order */
2278 sqlite3VdbeAddOp(v, OP_MoveGe, iIdxCur, brk);
2279 start = sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
2280 sqlite3VdbeOp3(v, OP_IdxGE, iIdxCur, brk, "+", P3_STATIC);
2281 pLevel->op = OP_Next;
2282 }
2283 sqlite3VdbeAddOp(v, OP_RowKey, iIdxCur, 0);
2284 sqlite3VdbeAddOp(v, OP_IdxIsNull, nEq, cont);
2285 if( !omitTable ){
2286 sqlite3VdbeAddOp(v, OP_IdxRowid, iIdxCur, 0);
2287 sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
2288 }
2289 pLevel->p1 = iIdxCur;
2290 pLevel->p2 = start;
drhfe05af82005-07-21 03:14:59 +00002291 }else{
2292 /* Case 5: There is no usable index. We must do a complete
2293 ** scan of the entire table.
2294 */
drhfe05af82005-07-21 03:14:59 +00002295 assert( omitTable==0 );
drha6110402005-07-28 20:51:19 +00002296 assert( bRev==0 );
2297 pLevel->op = OP_Next;
drhfe05af82005-07-21 03:14:59 +00002298 pLevel->p1 = iCur;
drha6110402005-07-28 20:51:19 +00002299 pLevel->p2 = 1 + sqlite3VdbeAddOp(v, OP_Rewind, iCur, brk);
drh75897232000-05-29 14:26:00 +00002300 }
drhfe05af82005-07-21 03:14:59 +00002301 notReady &= ~getMask(&maskSet, iCur);
drh75897232000-05-29 14:26:00 +00002302
2303 /* Insert code to test every subexpression that can be completely
2304 ** computed using the current set of tables.
2305 */
drh0fcef5e2005-07-19 17:38:22 +00002306 for(pTerm=wc.a, j=wc.nTerm; j>0; j--, pTerm++){
2307 Expr *pE;
2308 if( pTerm->flags & (TERM_VIRTUAL|TERM_CODED) ) continue;
drhfe05af82005-07-21 03:14:59 +00002309 if( (pTerm->prereqAll & notReady)!=0 ) continue;
drh0fcef5e2005-07-19 17:38:22 +00002310 pE = pTerm->pExpr;
2311 assert( pE!=0 );
drh392e5972005-07-08 14:14:22 +00002312 if( pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin) ){
drh1f162302002-10-27 19:35:33 +00002313 continue;
2314 }
drh392e5972005-07-08 14:14:22 +00002315 sqlite3ExprIfFalse(pParse, pE, cont, 1);
drh0fcef5e2005-07-19 17:38:22 +00002316 pTerm->flags |= TERM_CODED;
drh75897232000-05-29 14:26:00 +00002317 }
drhad2d8302002-05-24 20:31:36 +00002318
2319 /* For a LEFT OUTER JOIN, generate code that will record the fact that
2320 ** at least one row of the right table has matched the left table.
2321 */
2322 if( pLevel->iLeftJoin ){
danielk19774adee202004-05-08 08:23:19 +00002323 pLevel->top = sqlite3VdbeCurrentAddr(v);
drhd654be82005-09-20 17:42:23 +00002324 sqlite3VdbeAddOp(v, OP_MemInt, 1, pLevel->iLeftJoin);
drhad6d9462004-09-19 02:15:24 +00002325 VdbeComment((v, "# record LEFT JOIN hit"));
drh0aa74ed2005-07-16 13:33:20 +00002326 for(pTerm=wc.a, j=0; j<wc.nTerm; j++, pTerm++){
drh0fcef5e2005-07-19 17:38:22 +00002327 if( pTerm->flags & (TERM_VIRTUAL|TERM_CODED) ) continue;
drhfe05af82005-07-21 03:14:59 +00002328 if( (pTerm->prereqAll & notReady)!=0 ) continue;
drh0fcef5e2005-07-19 17:38:22 +00002329 assert( pTerm->pExpr );
2330 sqlite3ExprIfFalse(pParse, pTerm->pExpr, cont, 1);
2331 pTerm->flags |= TERM_CODED;
drh1cc093c2002-06-24 22:01:57 +00002332 }
drhad2d8302002-05-24 20:31:36 +00002333 }
drh75897232000-05-29 14:26:00 +00002334 }
drh7ec764a2005-07-21 03:48:20 +00002335
2336#ifdef SQLITE_TEST /* For testing and debugging use only */
2337 /* Record in the query plan information about the current table
2338 ** and the index used to access it (if any). If the table itself
2339 ** is not used, its name is just '{}'. If no index is used
2340 ** the index is listed as "{}". If the primary key is used the
2341 ** index name is '*'.
2342 */
2343 for(i=0; i<pTabList->nSrc; i++){
2344 char *z;
2345 int n;
drh7ec764a2005-07-21 03:48:20 +00002346 pLevel = &pWInfo->a[i];
drh29dda4a2005-07-21 18:23:20 +00002347 pTabItem = &pTabList->a[pLevel->iFrom];
drh7ec764a2005-07-21 03:48:20 +00002348 z = pTabItem->zAlias;
2349 if( z==0 ) z = pTabItem->pTab->zName;
2350 n = strlen(z);
2351 if( n+nQPlan < sizeof(sqlite3_query_plan)-10 ){
2352 if( pLevel->flags & WHERE_IDX_ONLY ){
2353 strcpy(&sqlite3_query_plan[nQPlan], "{}");
2354 nQPlan += 2;
2355 }else{
2356 strcpy(&sqlite3_query_plan[nQPlan], z);
2357 nQPlan += n;
2358 }
2359 sqlite3_query_plan[nQPlan++] = ' ';
2360 }
2361 if( pLevel->flags & (WHERE_ROWID_EQ|WHERE_ROWID_RANGE) ){
2362 strcpy(&sqlite3_query_plan[nQPlan], "* ");
2363 nQPlan += 2;
2364 }else if( pLevel->pIdx==0 ){
2365 strcpy(&sqlite3_query_plan[nQPlan], "{} ");
2366 nQPlan += 3;
2367 }else{
2368 n = strlen(pLevel->pIdx->zName);
2369 if( n+nQPlan < sizeof(sqlite3_query_plan)-2 ){
2370 strcpy(&sqlite3_query_plan[nQPlan], pLevel->pIdx->zName);
2371 nQPlan += n;
2372 sqlite3_query_plan[nQPlan++] = ' ';
2373 }
2374 }
2375 }
2376 while( nQPlan>0 && sqlite3_query_plan[nQPlan-1]==' ' ){
2377 sqlite3_query_plan[--nQPlan] = 0;
2378 }
2379 sqlite3_query_plan[nQPlan] = 0;
2380 nQPlan = 0;
2381#endif /* SQLITE_TEST // Testing and debugging use only */
2382
drh29dda4a2005-07-21 18:23:20 +00002383 /* Record the continuation address in the WhereInfo structure. Then
2384 ** clean up and return.
2385 */
drh75897232000-05-29 14:26:00 +00002386 pWInfo->iContinue = cont;
drh0aa74ed2005-07-16 13:33:20 +00002387 whereClauseClear(&wc);
drh75897232000-05-29 14:26:00 +00002388 return pWInfo;
drhe23399f2005-07-22 00:31:39 +00002389
2390 /* Jump here if malloc fails */
2391whereBeginNoMem:
2392 whereClauseClear(&wc);
drh9eff6162006-06-12 21:59:13 +00002393 whereInfoFree(pWInfo);
drhe23399f2005-07-22 00:31:39 +00002394 return 0;
drh75897232000-05-29 14:26:00 +00002395}
2396
2397/*
drhc27a1ce2002-06-14 20:58:45 +00002398** Generate the end of the WHERE loop. See comments on
danielk19774adee202004-05-08 08:23:19 +00002399** sqlite3WhereBegin() for additional information.
drh75897232000-05-29 14:26:00 +00002400*/
danielk19774adee202004-05-08 08:23:19 +00002401void sqlite3WhereEnd(WhereInfo *pWInfo){
drh75897232000-05-29 14:26:00 +00002402 Vdbe *v = pWInfo->pParse->pVdbe;
drh19a775c2000-06-05 18:54:46 +00002403 int i;
drh6b563442001-11-07 16:48:26 +00002404 WhereLevel *pLevel;
drhad3cab52002-05-24 02:04:32 +00002405 SrcList *pTabList = pWInfo->pTabList;
drh19a775c2000-06-05 18:54:46 +00002406
drh9012bcb2004-12-19 00:11:35 +00002407 /* Generate loop termination code.
2408 */
drhad3cab52002-05-24 02:04:32 +00002409 for(i=pTabList->nSrc-1; i>=0; i--){
drh6b563442001-11-07 16:48:26 +00002410 pLevel = &pWInfo->a[i];
danielk19774adee202004-05-08 08:23:19 +00002411 sqlite3VdbeResolveLabel(v, pLevel->cont);
drh6b563442001-11-07 16:48:26 +00002412 if( pLevel->op!=OP_Noop ){
danielk19774adee202004-05-08 08:23:19 +00002413 sqlite3VdbeAddOp(v, pLevel->op, pLevel->p1, pLevel->p2);
drh19a775c2000-06-05 18:54:46 +00002414 }
danielk19774adee202004-05-08 08:23:19 +00002415 sqlite3VdbeResolveLabel(v, pLevel->brk);
drhe23399f2005-07-22 00:31:39 +00002416 if( pLevel->nIn ){
2417 int *a;
2418 int j;
drhffe0f892006-05-11 13:26:25 +00002419 for(j=pLevel->nIn, a=&pLevel->aInLoop[j*2-2]; j>0; j--, a-=2){
2420 sqlite3VdbeAddOp(v, OP_Next, a[0], a[1]);
2421 sqlite3VdbeJumpHere(v, a[1]-1);
drhe23399f2005-07-22 00:31:39 +00002422 }
2423 sqliteFree(pLevel->aInLoop);
drhd99f7062002-06-08 23:25:08 +00002424 }
drhad2d8302002-05-24 20:31:36 +00002425 if( pLevel->iLeftJoin ){
2426 int addr;
drhd654be82005-09-20 17:42:23 +00002427 addr = sqlite3VdbeAddOp(v, OP_IfMemPos, pLevel->iLeftJoin, 0);
danielk19774adee202004-05-08 08:23:19 +00002428 sqlite3VdbeAddOp(v, OP_NullRow, pTabList->a[i].iCursor, 0);
drh9012bcb2004-12-19 00:11:35 +00002429 if( pLevel->iIdxCur>=0 ){
2430 sqlite3VdbeAddOp(v, OP_NullRow, pLevel->iIdxCur, 0);
drh7f09b3e2002-08-13 13:15:49 +00002431 }
danielk19774adee202004-05-08 08:23:19 +00002432 sqlite3VdbeAddOp(v, OP_Goto, 0, pLevel->top);
drhd654be82005-09-20 17:42:23 +00002433 sqlite3VdbeJumpHere(v, addr);
drhad2d8302002-05-24 20:31:36 +00002434 }
drh19a775c2000-06-05 18:54:46 +00002435 }
drh9012bcb2004-12-19 00:11:35 +00002436
2437 /* The "break" point is here, just past the end of the outer loop.
2438 ** Set it.
2439 */
danielk19774adee202004-05-08 08:23:19 +00002440 sqlite3VdbeResolveLabel(v, pWInfo->iBreak);
drh9012bcb2004-12-19 00:11:35 +00002441
drh29dda4a2005-07-21 18:23:20 +00002442 /* Close all of the cursors that were opened by sqlite3WhereBegin.
drh9012bcb2004-12-19 00:11:35 +00002443 */
drh29dda4a2005-07-21 18:23:20 +00002444 for(i=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){
2445 struct SrcList_item *pTabItem = &pTabList->a[pLevel->iFrom];
drh9012bcb2004-12-19 00:11:35 +00002446 Table *pTab = pTabItem->pTab;
drh5cf590c2003-04-24 01:45:04 +00002447 assert( pTab!=0 );
drhb9bb7c12006-06-11 23:41:55 +00002448 if( pTab->isEphem || pTab->pSelect ) continue;
drhfe05af82005-07-21 03:14:59 +00002449 if( (pLevel->flags & WHERE_IDX_ONLY)==0 ){
drh9012bcb2004-12-19 00:11:35 +00002450 sqlite3VdbeAddOp(v, OP_Close, pTabItem->iCursor, 0);
2451 }
drh6b563442001-11-07 16:48:26 +00002452 if( pLevel->pIdx!=0 ){
drh9012bcb2004-12-19 00:11:35 +00002453 sqlite3VdbeAddOp(v, OP_Close, pLevel->iIdxCur, 0);
2454 }
2455
drhacf3b982005-01-03 01:27:18 +00002456 /* Make cursor substitutions for cases where we want to use
drh9012bcb2004-12-19 00:11:35 +00002457 ** just the index and never reference the table.
2458 **
2459 ** Calls to the code generator in between sqlite3WhereBegin and
2460 ** sqlite3WhereEnd will have created code that references the table
2461 ** directly. This loop scans all that code looking for opcodes
2462 ** that reference the table and converts them into opcodes that
2463 ** reference the index.
2464 */
drhfe05af82005-07-21 03:14:59 +00002465 if( pLevel->flags & WHERE_IDX_ONLY ){
danielk1977f0113002006-01-24 12:09:17 +00002466 int k, j, last;
drh9012bcb2004-12-19 00:11:35 +00002467 VdbeOp *pOp;
2468 Index *pIdx = pLevel->pIdx;
2469
2470 assert( pIdx!=0 );
2471 pOp = sqlite3VdbeGetOp(v, pWInfo->iTop);
2472 last = sqlite3VdbeCurrentAddr(v);
danielk1977f0113002006-01-24 12:09:17 +00002473 for(k=pWInfo->iTop; k<last; k++, pOp++){
drh9012bcb2004-12-19 00:11:35 +00002474 if( pOp->p1!=pLevel->iTabCur ) continue;
2475 if( pOp->opcode==OP_Column ){
2476 pOp->p1 = pLevel->iIdxCur;
2477 for(j=0; j<pIdx->nColumn; j++){
2478 if( pOp->p2==pIdx->aiColumn[j] ){
2479 pOp->p2 = j;
2480 break;
2481 }
2482 }
drhf0863fe2005-06-12 21:35:51 +00002483 }else if( pOp->opcode==OP_Rowid ){
drh9012bcb2004-12-19 00:11:35 +00002484 pOp->p1 = pLevel->iIdxCur;
drhf0863fe2005-06-12 21:35:51 +00002485 pOp->opcode = OP_IdxRowid;
danielk19776c18b6e2005-01-30 09:17:58 +00002486 }else if( pOp->opcode==OP_NullRow ){
2487 pOp->opcode = OP_Noop;
drh9012bcb2004-12-19 00:11:35 +00002488 }
2489 }
drh6b563442001-11-07 16:48:26 +00002490 }
drh19a775c2000-06-05 18:54:46 +00002491 }
drh9012bcb2004-12-19 00:11:35 +00002492
2493 /* Final cleanup
2494 */
drh9eff6162006-06-12 21:59:13 +00002495 whereInfoFree(pWInfo);
drh75897232000-05-29 14:26:00 +00002496 return;
2497}