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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**
shane7bc71e52008-05-28 18:01:44 +000019** $Id: where.c,v 1.305 2008/05/28 18:01:45 shane 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/*
drh51147ba2005-07-23 22:59:55 +000029** Trace output macros
30*/
31#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
mlcreech3a00f902008-03-04 17:45:01 +000032int sqlite3WhereTrace = 0;
33# define WHERETRACE(X) if(sqlite3WhereTrace) sqlite3DebugPrintf X
drh51147ba2005-07-23 22:59:55 +000034#else
drh4f0c5872007-03-26 22:05:01 +000035# define WHERETRACE(X)
drh51147ba2005-07-23 22:59:55 +000036#endif
37
drh0fcef5e2005-07-19 17:38:22 +000038/* Forward reference
39*/
40typedef struct WhereClause WhereClause;
drh7b4fc6a2007-02-06 13:26:32 +000041typedef struct ExprMaskSet ExprMaskSet;
drh0aa74ed2005-07-16 13:33:20 +000042
43/*
drh75897232000-05-29 14:26:00 +000044** The query generator uses an array of instances of this structure to
45** help it analyze the subexpressions of the WHERE clause. Each WHERE
46** clause subexpression is separated from the others by an AND operator.
drh51669862004-12-18 18:40:26 +000047**
drh0fcef5e2005-07-19 17:38:22 +000048** All WhereTerms are collected into a single WhereClause structure.
49** The following identity holds:
drh51669862004-12-18 18:40:26 +000050**
drh0fcef5e2005-07-19 17:38:22 +000051** WhereTerm.pWC->a[WhereTerm.idx] == WhereTerm
drh51669862004-12-18 18:40:26 +000052**
drh0fcef5e2005-07-19 17:38:22 +000053** When a term is of the form:
54**
55** X <op> <expr>
56**
57** where X is a column name and <op> is one of certain operators,
58** then WhereTerm.leftCursor and WhereTerm.leftColumn record the
drh51147ba2005-07-23 22:59:55 +000059** cursor number and column number for X. WhereTerm.operator records
60** the <op> using a bitmask encoding defined by WO_xxx below. The
61** use of a bitmask encoding for the operator allows us to search
62** quickly for terms that match any of several different operators.
drh0fcef5e2005-07-19 17:38:22 +000063**
64** prereqRight and prereqAll record sets of cursor numbers,
drh51669862004-12-18 18:40:26 +000065** but they do so indirectly. A single ExprMaskSet structure translates
66** cursor number into bits and the translated bit is stored in the prereq
67** fields. The translation is used in order to maximize the number of
68** bits that will fit in a Bitmask. The VDBE cursor numbers might be
69** spread out over the non-negative integers. For example, the cursor
70** numbers might be 3, 8, 9, 10, 20, 23, 41, and 45. The ExprMaskSet
71** translates these sparse cursor numbers into consecutive integers
72** beginning with 0 in order to make the best possible use of the available
73** bits in the Bitmask. So, in the example above, the cursor numbers
74** would be mapped into integers 0 through 7.
drh75897232000-05-29 14:26:00 +000075*/
drh0aa74ed2005-07-16 13:33:20 +000076typedef struct WhereTerm WhereTerm;
77struct WhereTerm {
drh0fcef5e2005-07-19 17:38:22 +000078 Expr *pExpr; /* Pointer to the subexpression */
drh45b1ee42005-08-02 17:48:22 +000079 i16 iParent; /* Disable pWC->a[iParent] when this term disabled */
drh0fcef5e2005-07-19 17:38:22 +000080 i16 leftCursor; /* Cursor number of X in "X <op> <expr>" */
81 i16 leftColumn; /* Column number of X in "X <op> <expr>" */
drhb52076c2006-01-23 13:22:09 +000082 u16 eOperator; /* A WO_xx value describing <op> */
drh6c30be82005-07-29 15:10:17 +000083 u8 flags; /* Bit flags. See below */
drh45b1ee42005-08-02 17:48:22 +000084 u8 nChild; /* Number of children that must disable us */
drh0fcef5e2005-07-19 17:38:22 +000085 WhereClause *pWC; /* The clause this term is part of */
86 Bitmask prereqRight; /* Bitmask of tables used by pRight */
drh51669862004-12-18 18:40:26 +000087 Bitmask prereqAll; /* Bitmask of tables referenced by p */
drh75897232000-05-29 14:26:00 +000088};
89
90/*
drh0aa74ed2005-07-16 13:33:20 +000091** Allowed values of WhereTerm.flags
92*/
drh6c30be82005-07-29 15:10:17 +000093#define TERM_DYNAMIC 0x01 /* Need to call sqlite3ExprDelete(pExpr) */
94#define TERM_VIRTUAL 0x02 /* Added by the optimizer. Do not code */
95#define TERM_CODED 0x04 /* This term is already coded */
drh45b1ee42005-08-02 17:48:22 +000096#define TERM_COPIED 0x08 /* Has a child */
drh6c30be82005-07-29 15:10:17 +000097#define TERM_OR_OK 0x10 /* Used during OR-clause processing */
drh0aa74ed2005-07-16 13:33:20 +000098
99/*
100** An instance of the following structure holds all information about a
101** WHERE clause. Mostly this is a container for one or more WhereTerms.
102*/
drh0aa74ed2005-07-16 13:33:20 +0000103struct WhereClause {
drhfe05af82005-07-21 03:14:59 +0000104 Parse *pParse; /* The parser context */
drh7b4fc6a2007-02-06 13:26:32 +0000105 ExprMaskSet *pMaskSet; /* Mapping of table indices to bitmasks */
drh0aa74ed2005-07-16 13:33:20 +0000106 int nTerm; /* Number of terms */
107 int nSlot; /* Number of entries in a[] */
drh51147ba2005-07-23 22:59:55 +0000108 WhereTerm *a; /* Each a[] describes a term of the WHERE cluase */
109 WhereTerm aStatic[10]; /* Initial static space for a[] */
drhe23399f2005-07-22 00:31:39 +0000110};
111
112/*
drh6a3ea0e2003-05-02 14:32:12 +0000113** An instance of the following structure keeps track of a mapping
drh0aa74ed2005-07-16 13:33:20 +0000114** between VDBE cursor numbers and bits of the bitmasks in WhereTerm.
drh51669862004-12-18 18:40:26 +0000115**
116** The VDBE cursor numbers are small integers contained in
117** SrcList_item.iCursor and Expr.iTable fields. For any given WHERE
118** clause, the cursor numbers might not begin with 0 and they might
119** contain gaps in the numbering sequence. But we want to make maximum
120** use of the bits in our bitmasks. This structure provides a mapping
121** from the sparse cursor numbers into consecutive integers beginning
122** with 0.
123**
124** If ExprMaskSet.ix[A]==B it means that The A-th bit of a Bitmask
125** corresponds VDBE cursor number B. The A-th bit of a bitmask is 1<<A.
126**
127** For example, if the WHERE clause expression used these VDBE
128** cursors: 4, 5, 8, 29, 57, 73. Then the ExprMaskSet structure
129** would map those cursor numbers into bits 0 through 5.
130**
131** Note that the mapping is not necessarily ordered. In the example
132** above, the mapping might go like this: 4->3, 5->1, 8->2, 29->0,
133** 57->5, 73->4. Or one of 719 other combinations might be used. It
134** does not really matter. What is important is that sparse cursor
135** numbers all get mapped into bit numbers that begin with 0 and contain
136** no gaps.
drh6a3ea0e2003-05-02 14:32:12 +0000137*/
drh6a3ea0e2003-05-02 14:32:12 +0000138struct ExprMaskSet {
drh1398ad32005-01-19 23:24:50 +0000139 int n; /* Number of assigned cursor values */
140 int ix[sizeof(Bitmask)*8]; /* Cursor assigned to each bit */
drh6a3ea0e2003-05-02 14:32:12 +0000141};
142
drh0aa74ed2005-07-16 13:33:20 +0000143
drh6a3ea0e2003-05-02 14:32:12 +0000144/*
drh51147ba2005-07-23 22:59:55 +0000145** Bitmasks for the operators that indices are able to exploit. An
146** OR-ed combination of these values can be used when searching for
147** terms in the where clause.
148*/
149#define WO_IN 1
drha6110402005-07-28 20:51:19 +0000150#define WO_EQ 2
drh51147ba2005-07-23 22:59:55 +0000151#define WO_LT (WO_EQ<<(TK_LT-TK_EQ))
152#define WO_LE (WO_EQ<<(TK_LE-TK_EQ))
153#define WO_GT (WO_EQ<<(TK_GT-TK_EQ))
154#define WO_GE (WO_EQ<<(TK_GE-TK_EQ))
drh7f375902006-06-13 17:38:59 +0000155#define WO_MATCH 64
drh50b39962006-10-28 00:28:09 +0000156#define WO_ISNULL 128
drh51147ba2005-07-23 22:59:55 +0000157
158/*
drhf2d315d2007-01-25 16:56:06 +0000159** Value for flags returned by bestIndex().
160**
161** The least significant byte is reserved as a mask for WO_ values above.
162** The WhereLevel.flags field is usually set to WO_IN|WO_EQ|WO_ISNULL.
163** But if the table is the right table of a left join, WhereLevel.flags
164** is set to WO_IN|WO_EQ. The WhereLevel.flags field can then be used as
165** the "op" parameter to findTerm when we are resolving equality constraints.
166** ISNULL constraints will then not be used on the right table of a left
167** join. Tickets #2177 and #2189.
drh51147ba2005-07-23 22:59:55 +0000168*/
drhf2d315d2007-01-25 16:56:06 +0000169#define WHERE_ROWID_EQ 0x000100 /* rowid=EXPR or rowid IN (...) */
170#define WHERE_ROWID_RANGE 0x000200 /* rowid<EXPR and/or rowid>EXPR */
171#define WHERE_COLUMN_EQ 0x001000 /* x=EXPR or x IN (...) */
172#define WHERE_COLUMN_RANGE 0x002000 /* x<EXPR and/or x>EXPR */
173#define WHERE_COLUMN_IN 0x004000 /* x IN (...) */
174#define WHERE_TOP_LIMIT 0x010000 /* x<EXPR or x<=EXPR constraint */
175#define WHERE_BTM_LIMIT 0x020000 /* x>EXPR or x>=EXPR constraint */
176#define WHERE_IDX_ONLY 0x080000 /* Use index only - omit table */
177#define WHERE_ORDERBY 0x100000 /* Output will appear in correct order */
178#define WHERE_REVERSE 0x200000 /* Scan in reverse order */
179#define WHERE_UNIQUE 0x400000 /* Selects no more than one row */
180#define WHERE_VIRTUALTABLE 0x800000 /* Use virtual-table processing */
drh51147ba2005-07-23 22:59:55 +0000181
182/*
drh0aa74ed2005-07-16 13:33:20 +0000183** Initialize a preallocated WhereClause structure.
drh75897232000-05-29 14:26:00 +0000184*/
drh7b4fc6a2007-02-06 13:26:32 +0000185static void whereClauseInit(
186 WhereClause *pWC, /* The WhereClause to be initialized */
187 Parse *pParse, /* The parsing context */
188 ExprMaskSet *pMaskSet /* Mapping from table indices to bitmasks */
189){
drhfe05af82005-07-21 03:14:59 +0000190 pWC->pParse = pParse;
drh7b4fc6a2007-02-06 13:26:32 +0000191 pWC->pMaskSet = pMaskSet;
drh0aa74ed2005-07-16 13:33:20 +0000192 pWC->nTerm = 0;
drhcad651e2007-04-20 12:22:01 +0000193 pWC->nSlot = ArraySize(pWC->aStatic);
drh0aa74ed2005-07-16 13:33:20 +0000194 pWC->a = pWC->aStatic;
195}
196
197/*
198** Deallocate a WhereClause structure. The WhereClause structure
199** itself is not freed. This routine is the inverse of whereClauseInit().
200*/
201static void whereClauseClear(WhereClause *pWC){
202 int i;
203 WhereTerm *a;
204 for(i=pWC->nTerm-1, a=pWC->a; i>=0; i--, a++){
205 if( a->flags & TERM_DYNAMIC ){
drh0fcef5e2005-07-19 17:38:22 +0000206 sqlite3ExprDelete(a->pExpr);
drh0aa74ed2005-07-16 13:33:20 +0000207 }
208 }
209 if( pWC->a!=pWC->aStatic ){
drh17435752007-08-16 04:30:38 +0000210 sqlite3_free(pWC->a);
drh0aa74ed2005-07-16 13:33:20 +0000211 }
212}
213
214/*
215** Add a new entries to the WhereClause structure. Increase the allocated
216** space as necessary.
drh9eb20282005-08-24 03:52:18 +0000217**
drhb63a53d2007-03-31 01:34:44 +0000218** If the flags argument includes TERM_DYNAMIC, then responsibility
219** for freeing the expression p is assumed by the WhereClause object.
220**
drh9eb20282005-08-24 03:52:18 +0000221** WARNING: This routine might reallocate the space used to store
222** WhereTerms. All pointers to WhereTerms should be invalided after
223** calling this routine. Such pointers may be reinitialized by referencing
224** the pWC->a[] array.
drh0aa74ed2005-07-16 13:33:20 +0000225*/
drh9eb20282005-08-24 03:52:18 +0000226static int whereClauseInsert(WhereClause *pWC, Expr *p, int flags){
drh0aa74ed2005-07-16 13:33:20 +0000227 WhereTerm *pTerm;
drh9eb20282005-08-24 03:52:18 +0000228 int idx;
drh0aa74ed2005-07-16 13:33:20 +0000229 if( pWC->nTerm>=pWC->nSlot ){
230 WhereTerm *pOld = pWC->a;
drh17435752007-08-16 04:30:38 +0000231 pWC->a = sqlite3_malloc( sizeof(pWC->a[0])*pWC->nSlot*2 );
drhb63a53d2007-03-31 01:34:44 +0000232 if( pWC->a==0 ){
drh17435752007-08-16 04:30:38 +0000233 pWC->pParse->db->mallocFailed = 1;
drhb63a53d2007-03-31 01:34:44 +0000234 if( flags & TERM_DYNAMIC ){
235 sqlite3ExprDelete(p);
236 }
drhf998b732007-11-26 13:36:00 +0000237 pWC->a = pOld;
drhb63a53d2007-03-31 01:34:44 +0000238 return 0;
239 }
drh0aa74ed2005-07-16 13:33:20 +0000240 memcpy(pWC->a, pOld, sizeof(pWC->a[0])*pWC->nTerm);
241 if( pOld!=pWC->aStatic ){
drh17435752007-08-16 04:30:38 +0000242 sqlite3_free(pOld);
drh0aa74ed2005-07-16 13:33:20 +0000243 }
244 pWC->nSlot *= 2;
245 }
drh9eb20282005-08-24 03:52:18 +0000246 pTerm = &pWC->a[idx = pWC->nTerm];
drh0fcef5e2005-07-19 17:38:22 +0000247 pWC->nTerm++;
248 pTerm->pExpr = p;
drh0aa74ed2005-07-16 13:33:20 +0000249 pTerm->flags = flags;
drh0fcef5e2005-07-19 17:38:22 +0000250 pTerm->pWC = pWC;
drh45b1ee42005-08-02 17:48:22 +0000251 pTerm->iParent = -1;
drh9eb20282005-08-24 03:52:18 +0000252 return idx;
drh0aa74ed2005-07-16 13:33:20 +0000253}
drh75897232000-05-29 14:26:00 +0000254
255/*
drh51669862004-12-18 18:40:26 +0000256** This routine identifies subexpressions in the WHERE clause where
drhb6fb62d2005-09-20 08:47:20 +0000257** each subexpression is separated by the AND operator or some other
drh6c30be82005-07-29 15:10:17 +0000258** operator specified in the op parameter. The WhereClause structure
259** is filled with pointers to subexpressions. For example:
drh75897232000-05-29 14:26:00 +0000260**
drh51669862004-12-18 18:40:26 +0000261** WHERE a=='hello' AND coalesce(b,11)<10 AND (c+12!=d OR c==22)
262** \________/ \_______________/ \________________/
263** slot[0] slot[1] slot[2]
264**
265** The original WHERE clause in pExpr is unaltered. All this routine
drh51147ba2005-07-23 22:59:55 +0000266** does is make slot[] entries point to substructure within pExpr.
drh51669862004-12-18 18:40:26 +0000267**
drh51147ba2005-07-23 22:59:55 +0000268** In the previous sentence and in the diagram, "slot[]" refers to
269** the WhereClause.a[] array. This array grows as needed to contain
270** all terms of the WHERE clause.
drh75897232000-05-29 14:26:00 +0000271*/
drh6c30be82005-07-29 15:10:17 +0000272static void whereSplit(WhereClause *pWC, Expr *pExpr, int op){
drh0aa74ed2005-07-16 13:33:20 +0000273 if( pExpr==0 ) return;
drh6c30be82005-07-29 15:10:17 +0000274 if( pExpr->op!=op ){
drh0aa74ed2005-07-16 13:33:20 +0000275 whereClauseInsert(pWC, pExpr, 0);
drh75897232000-05-29 14:26:00 +0000276 }else{
drh6c30be82005-07-29 15:10:17 +0000277 whereSplit(pWC, pExpr->pLeft, op);
278 whereSplit(pWC, pExpr->pRight, op);
drh75897232000-05-29 14:26:00 +0000279 }
drh75897232000-05-29 14:26:00 +0000280}
281
282/*
drh6a3ea0e2003-05-02 14:32:12 +0000283** Initialize an expression mask set
284*/
285#define initMaskSet(P) memset(P, 0, sizeof(*P))
286
287/*
drh1398ad32005-01-19 23:24:50 +0000288** Return the bitmask for the given cursor number. Return 0 if
289** iCursor is not in the set.
drh6a3ea0e2003-05-02 14:32:12 +0000290*/
drh51669862004-12-18 18:40:26 +0000291static Bitmask getMask(ExprMaskSet *pMaskSet, int iCursor){
drh6a3ea0e2003-05-02 14:32:12 +0000292 int i;
293 for(i=0; i<pMaskSet->n; i++){
drh51669862004-12-18 18:40:26 +0000294 if( pMaskSet->ix[i]==iCursor ){
295 return ((Bitmask)1)<<i;
296 }
drh6a3ea0e2003-05-02 14:32:12 +0000297 }
drh6a3ea0e2003-05-02 14:32:12 +0000298 return 0;
299}
300
301/*
drh1398ad32005-01-19 23:24:50 +0000302** Create a new mask for cursor iCursor.
drh0fcef5e2005-07-19 17:38:22 +0000303**
304** There is one cursor per table in the FROM clause. The number of
305** tables in the FROM clause is limited by a test early in the
drhb6fb62d2005-09-20 08:47:20 +0000306** sqlite3WhereBegin() routine. So we know that the pMaskSet->ix[]
drh0fcef5e2005-07-19 17:38:22 +0000307** array will never overflow.
drh1398ad32005-01-19 23:24:50 +0000308*/
309static void createMask(ExprMaskSet *pMaskSet, int iCursor){
drhcad651e2007-04-20 12:22:01 +0000310 assert( pMaskSet->n < ArraySize(pMaskSet->ix) );
drh0fcef5e2005-07-19 17:38:22 +0000311 pMaskSet->ix[pMaskSet->n++] = iCursor;
drh1398ad32005-01-19 23:24:50 +0000312}
313
314/*
drh75897232000-05-29 14:26:00 +0000315** This routine walks (recursively) an expression tree and generates
316** a bitmask indicating which tables are used in that expression
drh6a3ea0e2003-05-02 14:32:12 +0000317** tree.
drh75897232000-05-29 14:26:00 +0000318**
319** In order for this routine to work, the calling function must have
drh626a8792005-01-17 22:08:19 +0000320** previously invoked sqlite3ExprResolveNames() on the expression. See
drh75897232000-05-29 14:26:00 +0000321** the header comment on that routine for additional information.
drh626a8792005-01-17 22:08:19 +0000322** The sqlite3ExprResolveNames() routines looks for column names and
drh6a3ea0e2003-05-02 14:32:12 +0000323** sets their opcodes to TK_COLUMN and their Expr.iTable fields to
drh51147ba2005-07-23 22:59:55 +0000324** the VDBE cursor number of the table. This routine just has to
325** translate the cursor numbers into bitmask values and OR all
326** the bitmasks together.
drh75897232000-05-29 14:26:00 +0000327*/
drhf5b11382005-09-17 13:07:13 +0000328static Bitmask exprListTableUsage(ExprMaskSet*, ExprList*);
329static Bitmask exprSelectTableUsage(ExprMaskSet*, Select*);
drh51669862004-12-18 18:40:26 +0000330static Bitmask exprTableUsage(ExprMaskSet *pMaskSet, Expr *p){
331 Bitmask mask = 0;
drh75897232000-05-29 14:26:00 +0000332 if( p==0 ) return 0;
drh967e8b72000-06-21 13:59:10 +0000333 if( p->op==TK_COLUMN ){
drh8feb4b12004-07-19 02:12:14 +0000334 mask = getMask(pMaskSet, p->iTable);
drh8feb4b12004-07-19 02:12:14 +0000335 return mask;
drh75897232000-05-29 14:26:00 +0000336 }
danielk1977b3bce662005-01-29 08:32:43 +0000337 mask = exprTableUsage(pMaskSet, p->pRight);
338 mask |= exprTableUsage(pMaskSet, p->pLeft);
339 mask |= exprListTableUsage(pMaskSet, p->pList);
drhf5b11382005-09-17 13:07:13 +0000340 mask |= exprSelectTableUsage(pMaskSet, p->pSelect);
danielk1977b3bce662005-01-29 08:32:43 +0000341 return mask;
342}
343static Bitmask exprListTableUsage(ExprMaskSet *pMaskSet, ExprList *pList){
344 int i;
345 Bitmask mask = 0;
346 if( pList ){
347 for(i=0; i<pList->nExpr; i++){
348 mask |= exprTableUsage(pMaskSet, pList->a[i].pExpr);
drhdd579122002-04-02 01:58:57 +0000349 }
350 }
drh75897232000-05-29 14:26:00 +0000351 return mask;
352}
drhf5b11382005-09-17 13:07:13 +0000353static Bitmask exprSelectTableUsage(ExprMaskSet *pMaskSet, Select *pS){
drha430ae82007-09-12 15:41:01 +0000354 Bitmask mask = 0;
355 while( pS ){
356 mask |= exprListTableUsage(pMaskSet, pS->pEList);
drhf5b11382005-09-17 13:07:13 +0000357 mask |= exprListTableUsage(pMaskSet, pS->pGroupBy);
358 mask |= exprListTableUsage(pMaskSet, pS->pOrderBy);
359 mask |= exprTableUsage(pMaskSet, pS->pWhere);
360 mask |= exprTableUsage(pMaskSet, pS->pHaving);
drha430ae82007-09-12 15:41:01 +0000361 pS = pS->pPrior;
drhf5b11382005-09-17 13:07:13 +0000362 }
363 return mask;
364}
drh75897232000-05-29 14:26:00 +0000365
366/*
drh487ab3c2001-11-08 00:45:21 +0000367** Return TRUE if the given operator is one of the operators that is
drh51669862004-12-18 18:40:26 +0000368** allowed for an indexable WHERE clause term. The allowed operators are
drhc27a1ce2002-06-14 20:58:45 +0000369** "=", "<", ">", "<=", ">=", and "IN".
drh487ab3c2001-11-08 00:45:21 +0000370*/
371static int allowedOp(int op){
drhfe05af82005-07-21 03:14:59 +0000372 assert( TK_GT>TK_EQ && TK_GT<TK_GE );
373 assert( TK_LT>TK_EQ && TK_LT<TK_GE );
374 assert( TK_LE>TK_EQ && TK_LE<TK_GE );
375 assert( TK_GE==TK_EQ+4 );
drh50b39962006-10-28 00:28:09 +0000376 return op==TK_IN || (op>=TK_EQ && op<=TK_GE) || op==TK_ISNULL;
drh487ab3c2001-11-08 00:45:21 +0000377}
378
379/*
drh51669862004-12-18 18:40:26 +0000380** Swap two objects of type T.
drh193bd772004-07-20 18:23:14 +0000381*/
382#define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;}
383
384/*
drh0fcef5e2005-07-19 17:38:22 +0000385** Commute a comparision operator. Expressions of the form "X op Y"
386** are converted into "Y op X".
danielk1977eb5453d2007-07-30 14:40:48 +0000387**
388** If a collation sequence is associated with either the left or right
389** side of the comparison, it remains associated with the same side after
390** the commutation. So "Y collate NOCASE op X" becomes
391** "X collate NOCASE op Y". This is because any collation sequence on
392** the left hand side of a comparison overrides any collation sequence
393** attached to the right. For the same reason the EP_ExpCollate flag
394** is not commuted.
drh193bd772004-07-20 18:23:14 +0000395*/
drh0fcef5e2005-07-19 17:38:22 +0000396static void exprCommute(Expr *pExpr){
danielk1977eb5453d2007-07-30 14:40:48 +0000397 u16 expRight = (pExpr->pRight->flags & EP_ExpCollate);
398 u16 expLeft = (pExpr->pLeft->flags & EP_ExpCollate);
drhfe05af82005-07-21 03:14:59 +0000399 assert( allowedOp(pExpr->op) && pExpr->op!=TK_IN );
drh0fcef5e2005-07-19 17:38:22 +0000400 SWAP(CollSeq*,pExpr->pRight->pColl,pExpr->pLeft->pColl);
danielk1977eb5453d2007-07-30 14:40:48 +0000401 pExpr->pRight->flags = (pExpr->pRight->flags & ~EP_ExpCollate) | expLeft;
402 pExpr->pLeft->flags = (pExpr->pLeft->flags & ~EP_ExpCollate) | expRight;
drh0fcef5e2005-07-19 17:38:22 +0000403 SWAP(Expr*,pExpr->pRight,pExpr->pLeft);
404 if( pExpr->op>=TK_GT ){
405 assert( TK_LT==TK_GT+2 );
406 assert( TK_GE==TK_LE+2 );
407 assert( TK_GT>TK_EQ );
408 assert( TK_GT<TK_LE );
409 assert( pExpr->op>=TK_GT && pExpr->op<=TK_GE );
410 pExpr->op = ((pExpr->op-TK_GT)^2)+TK_GT;
drh193bd772004-07-20 18:23:14 +0000411 }
drh193bd772004-07-20 18:23:14 +0000412}
413
414/*
drhfe05af82005-07-21 03:14:59 +0000415** Translate from TK_xx operator to WO_xx bitmask.
416*/
417static int operatorMask(int op){
drh51147ba2005-07-23 22:59:55 +0000418 int c;
drhfe05af82005-07-21 03:14:59 +0000419 assert( allowedOp(op) );
420 if( op==TK_IN ){
drh51147ba2005-07-23 22:59:55 +0000421 c = WO_IN;
drh50b39962006-10-28 00:28:09 +0000422 }else if( op==TK_ISNULL ){
423 c = WO_ISNULL;
drhfe05af82005-07-21 03:14:59 +0000424 }else{
drh51147ba2005-07-23 22:59:55 +0000425 c = WO_EQ<<(op-TK_EQ);
drhfe05af82005-07-21 03:14:59 +0000426 }
drh50b39962006-10-28 00:28:09 +0000427 assert( op!=TK_ISNULL || c==WO_ISNULL );
drh51147ba2005-07-23 22:59:55 +0000428 assert( op!=TK_IN || c==WO_IN );
429 assert( op!=TK_EQ || c==WO_EQ );
430 assert( op!=TK_LT || c==WO_LT );
431 assert( op!=TK_LE || c==WO_LE );
432 assert( op!=TK_GT || c==WO_GT );
433 assert( op!=TK_GE || c==WO_GE );
434 return c;
drhfe05af82005-07-21 03:14:59 +0000435}
436
437/*
438** Search for a term in the WHERE clause that is of the form "X <op> <expr>"
439** where X is a reference to the iColumn of table iCur and <op> is one of
440** the WO_xx operator codes specified by the op parameter.
441** Return a pointer to the term. Return 0 if not found.
442*/
443static WhereTerm *findTerm(
444 WhereClause *pWC, /* The WHERE clause to be searched */
445 int iCur, /* Cursor number of LHS */
446 int iColumn, /* Column number of LHS */
447 Bitmask notReady, /* RHS must not overlap with this mask */
drh51147ba2005-07-23 22:59:55 +0000448 u16 op, /* Mask of WO_xx values describing operator */
drhfe05af82005-07-21 03:14:59 +0000449 Index *pIdx /* Must be compatible with this index, if not NULL */
450){
451 WhereTerm *pTerm;
452 int k;
453 for(pTerm=pWC->a, k=pWC->nTerm; k; k--, pTerm++){
454 if( pTerm->leftCursor==iCur
455 && (pTerm->prereqRight & notReady)==0
456 && pTerm->leftColumn==iColumn
drhb52076c2006-01-23 13:22:09 +0000457 && (pTerm->eOperator & op)!=0
drhfe05af82005-07-21 03:14:59 +0000458 ){
drh50b39962006-10-28 00:28:09 +0000459 if( iCur>=0 && pIdx && pTerm->eOperator!=WO_ISNULL ){
drhfe05af82005-07-21 03:14:59 +0000460 Expr *pX = pTerm->pExpr;
461 CollSeq *pColl;
462 char idxaff;
danielk1977f0113002006-01-24 12:09:17 +0000463 int j;
drhfe05af82005-07-21 03:14:59 +0000464 Parse *pParse = pWC->pParse;
465
466 idxaff = pIdx->pTable->aCol[iColumn].affinity;
467 if( !sqlite3IndexAffinityOk(pX, idxaff) ) continue;
danielk1977bcbb04e2007-05-29 12:11:29 +0000468
469 /* Figure out the collation sequence required from an index for
470 ** it to be useful for optimising expression pX. Store this
471 ** value in variable pColl.
472 */
473 assert(pX->pLeft);
474 pColl = sqlite3BinaryCompareCollSeq(pParse, pX->pLeft, pX->pRight);
drhfe05af82005-07-21 03:14:59 +0000475 if( !pColl ){
danielk1977bcbb04e2007-05-29 12:11:29 +0000476 pColl = pParse->db->pDfltColl;
drhfe05af82005-07-21 03:14:59 +0000477 }
danielk1977bcbb04e2007-05-29 12:11:29 +0000478
danielk1977f0113002006-01-24 12:09:17 +0000479 for(j=0; j<pIdx->nColumn && pIdx->aiColumn[j]!=iColumn; j++){}
480 assert( j<pIdx->nColumn );
481 if( sqlite3StrICmp(pColl->zName, pIdx->azColl[j]) ) continue;
drhfe05af82005-07-21 03:14:59 +0000482 }
483 return pTerm;
484 }
485 }
486 return 0;
487}
488
drh6c30be82005-07-29 15:10:17 +0000489/* Forward reference */
drh7b4fc6a2007-02-06 13:26:32 +0000490static void exprAnalyze(SrcList*, WhereClause*, int);
drh6c30be82005-07-29 15:10:17 +0000491
492/*
493** Call exprAnalyze on all terms in a WHERE clause.
494**
495**
496*/
497static void exprAnalyzeAll(
498 SrcList *pTabList, /* the FROM clause */
drh6c30be82005-07-29 15:10:17 +0000499 WhereClause *pWC /* the WHERE clause to be analyzed */
500){
drh6c30be82005-07-29 15:10:17 +0000501 int i;
drh9eb20282005-08-24 03:52:18 +0000502 for(i=pWC->nTerm-1; i>=0; i--){
drh7b4fc6a2007-02-06 13:26:32 +0000503 exprAnalyze(pTabList, pWC, i);
drh6c30be82005-07-29 15:10:17 +0000504 }
505}
506
drhd2687b72005-08-12 22:56:09 +0000507#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
508/*
509** Check to see if the given expression is a LIKE or GLOB operator that
510** can be optimized using inequality constraints. Return TRUE if it is
511** so and false if not.
512**
513** In order for the operator to be optimizible, the RHS must be a string
514** literal that does not begin with a wildcard.
515*/
516static int isLikeOrGlob(
drh55ef4d92005-08-14 01:20:37 +0000517 sqlite3 *db, /* The database */
drhd2687b72005-08-12 22:56:09 +0000518 Expr *pExpr, /* Test this expression */
519 int *pnPattern, /* Number of non-wildcard prefix characters */
drh9f504ea2008-02-23 21:55:39 +0000520 int *pisComplete, /* True if the only wildcard is % in the last character */
521 int *pnoCase /* True if uppercase is equivalent to lowercase */
drhd2687b72005-08-12 22:56:09 +0000522){
523 const char *z;
524 Expr *pRight, *pLeft;
drh55ef4d92005-08-14 01:20:37 +0000525 ExprList *pList;
drhd2687b72005-08-12 22:56:09 +0000526 int c, cnt;
drh55ef4d92005-08-14 01:20:37 +0000527 char wc[3];
drhd64fe2f2005-08-28 17:00:23 +0000528 CollSeq *pColl;
529
drh9f504ea2008-02-23 21:55:39 +0000530 if( !sqlite3IsLikeFunction(db, pExpr, pnoCase, wc) ){
drhd2687b72005-08-12 22:56:09 +0000531 return 0;
532 }
drh9f504ea2008-02-23 21:55:39 +0000533#ifdef SQLITE_EBCDIC
534 if( *pnoCase ) return 0;
535#endif
drh55ef4d92005-08-14 01:20:37 +0000536 pList = pExpr->pList;
537 pRight = pList->a[0].pExpr;
drh678ccce2008-03-31 18:19:54 +0000538 if( pRight->op!=TK_STRING
539 && (pRight->op!=TK_REGISTER || pRight->iColumn!=TK_STRING) ){
drhd2687b72005-08-12 22:56:09 +0000540 return 0;
541 }
drh55ef4d92005-08-14 01:20:37 +0000542 pLeft = pList->a[1].pExpr;
drhd2687b72005-08-12 22:56:09 +0000543 if( pLeft->op!=TK_COLUMN ){
544 return 0;
545 }
drhd64fe2f2005-08-28 17:00:23 +0000546 pColl = pLeft->pColl;
drh01495b92008-01-23 12:52:40 +0000547 assert( pColl!=0 || pLeft->iColumn==-1 );
drhd64fe2f2005-08-28 17:00:23 +0000548 if( pColl==0 ){
drh01495b92008-01-23 12:52:40 +0000549 /* No collation is defined for the ROWID. Use the default. */
drhd64fe2f2005-08-28 17:00:23 +0000550 pColl = db->pDfltColl;
551 }
drh9f504ea2008-02-23 21:55:39 +0000552 if( (pColl->type!=SQLITE_COLL_BINARY || *pnoCase) &&
553 (pColl->type!=SQLITE_COLL_NOCASE || !*pnoCase) ){
drhd64fe2f2005-08-28 17:00:23 +0000554 return 0;
555 }
drh17435752007-08-16 04:30:38 +0000556 sqlite3DequoteExpr(db, pRight);
danielk197700fd9572005-12-07 06:27:43 +0000557 z = (char *)pRight->token.z;
drhf998b732007-11-26 13:36:00 +0000558 cnt = 0;
559 if( z ){
560 while( (c=z[cnt])!=0 && c!=wc[0] && c!=wc[1] && c!=wc[2] ){ cnt++; }
561 }
drhd2687b72005-08-12 22:56:09 +0000562 if( cnt==0 || 255==(u8)z[cnt] ){
563 return 0;
564 }
drh55ef4d92005-08-14 01:20:37 +0000565 *pisComplete = z[cnt]==wc[0] && z[cnt+1]==0;
drhd2687b72005-08-12 22:56:09 +0000566 *pnPattern = cnt;
567 return 1;
568}
569#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
570
drhedb193b2006-06-27 13:20:21 +0000571
572#ifndef SQLITE_OMIT_VIRTUALTABLE
drhfe05af82005-07-21 03:14:59 +0000573/*
drh7f375902006-06-13 17:38:59 +0000574** Check to see if the given expression is of the form
575**
576** column MATCH expr
577**
578** If it is then return TRUE. If not, return FALSE.
579*/
580static int isMatchOfColumn(
581 Expr *pExpr /* Test this expression */
582){
583 ExprList *pList;
584
585 if( pExpr->op!=TK_FUNCTION ){
586 return 0;
587 }
drhedb193b2006-06-27 13:20:21 +0000588 if( pExpr->token.n!=5 ||
589 sqlite3StrNICmp((const char*)pExpr->token.z,"match",5)!=0 ){
drh7f375902006-06-13 17:38:59 +0000590 return 0;
591 }
592 pList = pExpr->pList;
593 if( pList->nExpr!=2 ){
594 return 0;
595 }
596 if( pList->a[1].pExpr->op != TK_COLUMN ){
597 return 0;
598 }
599 return 1;
600}
drhedb193b2006-06-27 13:20:21 +0000601#endif /* SQLITE_OMIT_VIRTUALTABLE */
drh7f375902006-06-13 17:38:59 +0000602
603/*
drh54a167d2005-11-26 14:08:07 +0000604** If the pBase expression originated in the ON or USING clause of
605** a join, then transfer the appropriate markings over to derived.
606*/
607static void transferJoinMarkings(Expr *pDerived, Expr *pBase){
608 pDerived->flags |= pBase->flags & EP_FromJoin;
609 pDerived->iRightJoinTable = pBase->iRightJoinTable;
610}
611
drh3e355802007-02-23 23:13:33 +0000612#if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY)
613/*
614** Return TRUE if the given term of an OR clause can be converted
615** into an IN clause. The iCursor and iColumn define the left-hand
616** side of the IN clause.
617**
618** The context is that we have multiple OR-connected equality terms
619** like this:
620**
621** a=<expr1> OR a=<expr2> OR b=<expr3> OR ...
622**
623** The pOrTerm input to this routine corresponds to a single term of
624** this OR clause. In order for the term to be a condidate for
625** conversion to an IN operator, the following must be true:
626**
627** * The left-hand side of the term must be the column which
628** is identified by iCursor and iColumn.
629**
630** * If the right-hand side is also a column, then the affinities
631** of both right and left sides must be such that no type
632** conversions are required on the right. (Ticket #2249)
633**
634** If both of these conditions are true, then return true. Otherwise
635** return false.
636*/
637static int orTermIsOptCandidate(WhereTerm *pOrTerm, int iCursor, int iColumn){
638 int affLeft, affRight;
639 assert( pOrTerm->eOperator==WO_EQ );
640 if( pOrTerm->leftCursor!=iCursor ){
641 return 0;
642 }
643 if( pOrTerm->leftColumn!=iColumn ){
644 return 0;
645 }
646 affRight = sqlite3ExprAffinity(pOrTerm->pExpr->pRight);
647 if( affRight==0 ){
648 return 1;
649 }
650 affLeft = sqlite3ExprAffinity(pOrTerm->pExpr->pLeft);
651 if( affRight!=affLeft ){
652 return 0;
653 }
654 return 1;
655}
656
657/*
658** Return true if the given term of an OR clause can be ignored during
659** a check to make sure all OR terms are candidates for optimization.
660** In other words, return true if a call to the orTermIsOptCandidate()
661** above returned false but it is not necessary to disqualify the
662** optimization.
663**
664** Suppose the original OR phrase was this:
665**
666** a=4 OR a=11 OR a=b
667**
668** During analysis, the third term gets flipped around and duplicate
669** so that we are left with this:
670**
671** a=4 OR a=11 OR a=b OR b=a
672**
673** Since the last two terms are duplicates, only one of them
674** has to qualify in order for the whole phrase to qualify. When
675** this routine is called, we know that pOrTerm did not qualify.
676** This routine merely checks to see if pOrTerm has a duplicate that
677** might qualify. If there is a duplicate that has not yet been
678** disqualified, then return true. If there are no duplicates, or
679** the duplicate has also been disqualifed, return false.
680*/
681static int orTermHasOkDuplicate(WhereClause *pOr, WhereTerm *pOrTerm){
682 if( pOrTerm->flags & TERM_COPIED ){
683 /* This is the original term. The duplicate is to the left had
684 ** has not yet been analyzed and thus has not yet been disqualified. */
685 return 1;
686 }
687 if( (pOrTerm->flags & TERM_VIRTUAL)!=0
688 && (pOr->a[pOrTerm->iParent].flags & TERM_OR_OK)!=0 ){
689 /* This is a duplicate term. The original qualified so this one
690 ** does not have to. */
691 return 1;
692 }
693 /* This is either a singleton term or else it is a duplicate for
694 ** which the original did not qualify. Either way we are done for. */
695 return 0;
696}
697#endif /* !SQLITE_OMIT_OR_OPTIMIZATION && !SQLITE_OMIT_SUBQUERY */
drh54a167d2005-11-26 14:08:07 +0000698
699/*
drh0aa74ed2005-07-16 13:33:20 +0000700** The input to this routine is an WhereTerm structure with only the
drh51147ba2005-07-23 22:59:55 +0000701** "pExpr" field filled in. The job of this routine is to analyze the
drh0aa74ed2005-07-16 13:33:20 +0000702** subexpression and populate all the other fields of the WhereTerm
drh75897232000-05-29 14:26:00 +0000703** structure.
drh51147ba2005-07-23 22:59:55 +0000704**
705** If the expression is of the form "<expr> <op> X" it gets commuted
706** to the standard form of "X <op> <expr>". If the expression is of
707** the form "X <op> Y" where both X and Y are columns, then the original
708** expression is unchanged and a new virtual expression of the form
drhb6fb62d2005-09-20 08:47:20 +0000709** "Y <op> X" is added to the WHERE clause and analyzed separately.
drh75897232000-05-29 14:26:00 +0000710*/
drh0fcef5e2005-07-19 17:38:22 +0000711static void exprAnalyze(
712 SrcList *pSrc, /* the FROM clause */
drh9eb20282005-08-24 03:52:18 +0000713 WhereClause *pWC, /* the WHERE clause */
714 int idxTerm /* Index of the term to be analyzed */
drh0fcef5e2005-07-19 17:38:22 +0000715){
drhf998b732007-11-26 13:36:00 +0000716 WhereTerm *pTerm;
717 ExprMaskSet *pMaskSet;
718 Expr *pExpr;
drh0fcef5e2005-07-19 17:38:22 +0000719 Bitmask prereqLeft;
720 Bitmask prereqAll;
drhdafc0ce2008-04-17 19:14:02 +0000721 Bitmask extraRight = 0;
drhd2687b72005-08-12 22:56:09 +0000722 int nPattern;
723 int isComplete;
drh9f504ea2008-02-23 21:55:39 +0000724 int noCase;
drh50b39962006-10-28 00:28:09 +0000725 int op;
danielk19771e536952007-08-16 10:09:01 +0000726 Parse *pParse = pWC->pParse;
727 sqlite3 *db = pParse->db;
drh0fcef5e2005-07-19 17:38:22 +0000728
drhf998b732007-11-26 13:36:00 +0000729 if( db->mallocFailed ){
730 return;
731 }
732 pTerm = &pWC->a[idxTerm];
733 pMaskSet = pWC->pMaskSet;
734 pExpr = pTerm->pExpr;
drh0fcef5e2005-07-19 17:38:22 +0000735 prereqLeft = exprTableUsage(pMaskSet, pExpr->pLeft);
drh50b39962006-10-28 00:28:09 +0000736 op = pExpr->op;
737 if( op==TK_IN ){
drhf5b11382005-09-17 13:07:13 +0000738 assert( pExpr->pRight==0 );
739 pTerm->prereqRight = exprListTableUsage(pMaskSet, pExpr->pList)
740 | exprSelectTableUsage(pMaskSet, pExpr->pSelect);
drh50b39962006-10-28 00:28:09 +0000741 }else if( op==TK_ISNULL ){
742 pTerm->prereqRight = 0;
drhf5b11382005-09-17 13:07:13 +0000743 }else{
744 pTerm->prereqRight = exprTableUsage(pMaskSet, pExpr->pRight);
745 }
drh22d6a532005-09-19 21:05:48 +0000746 prereqAll = exprTableUsage(pMaskSet, pExpr);
747 if( ExprHasProperty(pExpr, EP_FromJoin) ){
drh42165be2008-03-26 14:56:34 +0000748 Bitmask x = getMask(pMaskSet, pExpr->iRightJoinTable);
749 prereqAll |= x;
drhdafc0ce2008-04-17 19:14:02 +0000750 extraRight = x-1; /* ON clause terms may not be used with an index
751 ** on left table of a LEFT JOIN. Ticket #3015 */
drh22d6a532005-09-19 21:05:48 +0000752 }
753 pTerm->prereqAll = prereqAll;
drh0fcef5e2005-07-19 17:38:22 +0000754 pTerm->leftCursor = -1;
drh45b1ee42005-08-02 17:48:22 +0000755 pTerm->iParent = -1;
drhb52076c2006-01-23 13:22:09 +0000756 pTerm->eOperator = 0;
drh50b39962006-10-28 00:28:09 +0000757 if( allowedOp(op) && (pTerm->prereqRight & prereqLeft)==0 ){
drh0fcef5e2005-07-19 17:38:22 +0000758 Expr *pLeft = pExpr->pLeft;
759 Expr *pRight = pExpr->pRight;
760 if( pLeft->op==TK_COLUMN ){
761 pTerm->leftCursor = pLeft->iTable;
762 pTerm->leftColumn = pLeft->iColumn;
drh50b39962006-10-28 00:28:09 +0000763 pTerm->eOperator = operatorMask(op);
drh75897232000-05-29 14:26:00 +0000764 }
drh0fcef5e2005-07-19 17:38:22 +0000765 if( pRight && pRight->op==TK_COLUMN ){
766 WhereTerm *pNew;
767 Expr *pDup;
768 if( pTerm->leftCursor>=0 ){
drh9eb20282005-08-24 03:52:18 +0000769 int idxNew;
drh17435752007-08-16 04:30:38 +0000770 pDup = sqlite3ExprDup(db, pExpr);
771 if( db->mallocFailed ){
drhb63a53d2007-03-31 01:34:44 +0000772 sqlite3ExprDelete(pDup);
drh28f45912006-10-18 23:26:38 +0000773 return;
774 }
drh9eb20282005-08-24 03:52:18 +0000775 idxNew = whereClauseInsert(pWC, pDup, TERM_VIRTUAL|TERM_DYNAMIC);
776 if( idxNew==0 ) return;
777 pNew = &pWC->a[idxNew];
778 pNew->iParent = idxTerm;
779 pTerm = &pWC->a[idxTerm];
drh45b1ee42005-08-02 17:48:22 +0000780 pTerm->nChild = 1;
781 pTerm->flags |= TERM_COPIED;
drh0fcef5e2005-07-19 17:38:22 +0000782 }else{
783 pDup = pExpr;
784 pNew = pTerm;
785 }
786 exprCommute(pDup);
787 pLeft = pDup->pLeft;
788 pNew->leftCursor = pLeft->iTable;
789 pNew->leftColumn = pLeft->iColumn;
790 pNew->prereqRight = prereqLeft;
791 pNew->prereqAll = prereqAll;
drhb52076c2006-01-23 13:22:09 +0000792 pNew->eOperator = operatorMask(pDup->op);
drh75897232000-05-29 14:26:00 +0000793 }
794 }
drhed378002005-07-28 23:12:08 +0000795
drhd2687b72005-08-12 22:56:09 +0000796#ifndef SQLITE_OMIT_BETWEEN_OPTIMIZATION
drhed378002005-07-28 23:12:08 +0000797 /* If a term is the BETWEEN operator, create two new virtual terms
798 ** that define the range that the BETWEEN implements.
799 */
800 else if( pExpr->op==TK_BETWEEN ){
801 ExprList *pList = pExpr->pList;
802 int i;
803 static const u8 ops[] = {TK_GE, TK_LE};
804 assert( pList!=0 );
805 assert( pList->nExpr==2 );
806 for(i=0; i<2; i++){
807 Expr *pNewExpr;
drh9eb20282005-08-24 03:52:18 +0000808 int idxNew;
danielk1977a1644fd2007-08-29 12:31:25 +0000809 pNewExpr = sqlite3Expr(db, ops[i], sqlite3ExprDup(db, pExpr->pLeft),
drh17435752007-08-16 04:30:38 +0000810 sqlite3ExprDup(db, pList->a[i].pExpr), 0);
drh9eb20282005-08-24 03:52:18 +0000811 idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
drh7b4fc6a2007-02-06 13:26:32 +0000812 exprAnalyze(pSrc, pWC, idxNew);
drh9eb20282005-08-24 03:52:18 +0000813 pTerm = &pWC->a[idxTerm];
814 pWC->a[idxNew].iParent = idxTerm;
drhed378002005-07-28 23:12:08 +0000815 }
drh45b1ee42005-08-02 17:48:22 +0000816 pTerm->nChild = 2;
drhed378002005-07-28 23:12:08 +0000817 }
drhd2687b72005-08-12 22:56:09 +0000818#endif /* SQLITE_OMIT_BETWEEN_OPTIMIZATION */
drhed378002005-07-28 23:12:08 +0000819
danielk19771576cd92006-01-14 08:02:28 +0000820#if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY)
drh6c30be82005-07-29 15:10:17 +0000821 /* Attempt to convert OR-connected terms into an IN operator so that
drhf5b11382005-09-17 13:07:13 +0000822 ** they can make use of indices. Example:
823 **
824 ** x = expr1 OR expr2 = x OR x = expr3
825 **
826 ** is converted into
827 **
828 ** x IN (expr1,expr2,expr3)
danielk19771576cd92006-01-14 08:02:28 +0000829 **
830 ** This optimization must be omitted if OMIT_SUBQUERY is defined because
831 ** the compiler for the the IN operator is part of sub-queries.
drh6c30be82005-07-29 15:10:17 +0000832 */
833 else if( pExpr->op==TK_OR ){
834 int ok;
835 int i, j;
836 int iColumn, iCursor;
837 WhereClause sOr;
838 WhereTerm *pOrTerm;
839
840 assert( (pTerm->flags & TERM_DYNAMIC)==0 );
drh7b4fc6a2007-02-06 13:26:32 +0000841 whereClauseInit(&sOr, pWC->pParse, pMaskSet);
drh6c30be82005-07-29 15:10:17 +0000842 whereSplit(&sOr, pExpr, TK_OR);
drh7b4fc6a2007-02-06 13:26:32 +0000843 exprAnalyzeAll(pSrc, &sOr);
drh3e355802007-02-23 23:13:33 +0000844 assert( sOr.nTerm>=2 );
drh6c30be82005-07-29 15:10:17 +0000845 j = 0;
drha53b9142008-03-17 17:08:33 +0000846 if( db->mallocFailed ) goto or_not_possible;
drh6c30be82005-07-29 15:10:17 +0000847 do{
drh3e355802007-02-23 23:13:33 +0000848 assert( j<sOr.nTerm );
drh6c30be82005-07-29 15:10:17 +0000849 iColumn = sOr.a[j].leftColumn;
850 iCursor = sOr.a[j].leftCursor;
851 ok = iCursor>=0;
852 for(i=sOr.nTerm-1, pOrTerm=sOr.a; i>=0 && ok; i--, pOrTerm++){
drhb52076c2006-01-23 13:22:09 +0000853 if( pOrTerm->eOperator!=WO_EQ ){
drh6c30be82005-07-29 15:10:17 +0000854 goto or_not_possible;
855 }
drh3e355802007-02-23 23:13:33 +0000856 if( orTermIsOptCandidate(pOrTerm, iCursor, iColumn) ){
drh6c30be82005-07-29 15:10:17 +0000857 pOrTerm->flags |= TERM_OR_OK;
drh3e355802007-02-23 23:13:33 +0000858 }else if( orTermHasOkDuplicate(&sOr, pOrTerm) ){
drh6c30be82005-07-29 15:10:17 +0000859 pOrTerm->flags &= ~TERM_OR_OK;
860 }else{
861 ok = 0;
862 }
863 }
drh3e355802007-02-23 23:13:33 +0000864 }while( !ok && (sOr.a[j++].flags & TERM_COPIED)!=0 && j<2 );
drh6c30be82005-07-29 15:10:17 +0000865 if( ok ){
866 ExprList *pList = 0;
867 Expr *pNew, *pDup;
drh38276582006-11-06 15:10:05 +0000868 Expr *pLeft = 0;
drh6c30be82005-07-29 15:10:17 +0000869 for(i=sOr.nTerm-1, pOrTerm=sOr.a; i>=0 && ok; i--, pOrTerm++){
870 if( (pOrTerm->flags & TERM_OR_OK)==0 ) continue;
drh17435752007-08-16 04:30:38 +0000871 pDup = sqlite3ExprDup(db, pOrTerm->pExpr->pRight);
872 pList = sqlite3ExprListAppend(pWC->pParse, pList, pDup, 0);
drh38276582006-11-06 15:10:05 +0000873 pLeft = pOrTerm->pExpr->pLeft;
drh6c30be82005-07-29 15:10:17 +0000874 }
drh38276582006-11-06 15:10:05 +0000875 assert( pLeft!=0 );
drh17435752007-08-16 04:30:38 +0000876 pDup = sqlite3ExprDup(db, pLeft);
danielk1977a1644fd2007-08-29 12:31:25 +0000877 pNew = sqlite3Expr(db, TK_IN, pDup, 0, 0);
drh53f733c2005-09-16 02:38:09 +0000878 if( pNew ){
drh9a5f7472005-11-26 14:24:40 +0000879 int idxNew;
drh54a167d2005-11-26 14:08:07 +0000880 transferJoinMarkings(pNew, pExpr);
drh53f733c2005-09-16 02:38:09 +0000881 pNew->pList = pList;
drh9a5f7472005-11-26 14:24:40 +0000882 idxNew = whereClauseInsert(pWC, pNew, TERM_VIRTUAL|TERM_DYNAMIC);
drh7b4fc6a2007-02-06 13:26:32 +0000883 exprAnalyze(pSrc, pWC, idxNew);
drh9a5f7472005-11-26 14:24:40 +0000884 pTerm = &pWC->a[idxTerm];
885 pWC->a[idxNew].iParent = idxTerm;
886 pTerm->nChild = 1;
drh53f733c2005-09-16 02:38:09 +0000887 }else{
888 sqlite3ExprListDelete(pList);
889 }
drh6c30be82005-07-29 15:10:17 +0000890 }
891or_not_possible:
892 whereClauseClear(&sOr);
893 }
drhd2687b72005-08-12 22:56:09 +0000894#endif /* SQLITE_OMIT_OR_OPTIMIZATION */
895
896#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
897 /* Add constraints to reduce the search space on a LIKE or GLOB
898 ** operator.
drh9f504ea2008-02-23 21:55:39 +0000899 **
900 ** A like pattern of the form "x LIKE 'abc%'" is changed into constraints
901 **
902 ** x>='abc' AND x<'abd' AND x LIKE 'abc%'
903 **
904 ** The last character of the prefix "abc" is incremented to form the
shane7bc71e52008-05-28 18:01:44 +0000905 ** termination condition "abd".
drhd2687b72005-08-12 22:56:09 +0000906 */
drh9f504ea2008-02-23 21:55:39 +0000907 if( isLikeOrGlob(db, pExpr, &nPattern, &isComplete, &noCase) ){
drhd2687b72005-08-12 22:56:09 +0000908 Expr *pLeft, *pRight;
909 Expr *pStr1, *pStr2;
910 Expr *pNewExpr1, *pNewExpr2;
drh9eb20282005-08-24 03:52:18 +0000911 int idxNew1, idxNew2;
912
drhd2687b72005-08-12 22:56:09 +0000913 pLeft = pExpr->pList->a[1].pExpr;
914 pRight = pExpr->pList->a[0].pExpr;
drh17435752007-08-16 04:30:38 +0000915 pStr1 = sqlite3PExpr(pParse, TK_STRING, 0, 0, 0);
drhd2687b72005-08-12 22:56:09 +0000916 if( pStr1 ){
drh17435752007-08-16 04:30:38 +0000917 sqlite3TokenCopy(db, &pStr1->token, &pRight->token);
drhd2687b72005-08-12 22:56:09 +0000918 pStr1->token.n = nPattern;
drh9c86df52007-06-11 12:56:15 +0000919 pStr1->flags = EP_Dequoted;
drhd2687b72005-08-12 22:56:09 +0000920 }
drh17435752007-08-16 04:30:38 +0000921 pStr2 = sqlite3ExprDup(db, pStr1);
drhf998b732007-11-26 13:36:00 +0000922 if( !db->mallocFailed ){
drh9f504ea2008-02-23 21:55:39 +0000923 u8 c, *pC;
drhd2687b72005-08-12 22:56:09 +0000924 assert( pStr2->token.dyn );
drh9f504ea2008-02-23 21:55:39 +0000925 pC = (u8*)&pStr2->token.z[nPattern-1];
926 c = *pC;
drh02a50b72008-05-26 18:33:40 +0000927 if( noCase ){
928 if( c=='@' ) isComplete = 0;
929 c = sqlite3UpperToLower[c];
930 }
drh9f504ea2008-02-23 21:55:39 +0000931 *pC = c + 1;
drhd2687b72005-08-12 22:56:09 +0000932 }
drh17435752007-08-16 04:30:38 +0000933 pNewExpr1 = sqlite3PExpr(pParse, TK_GE, sqlite3ExprDup(db,pLeft), pStr1, 0);
drh9eb20282005-08-24 03:52:18 +0000934 idxNew1 = whereClauseInsert(pWC, pNewExpr1, TERM_VIRTUAL|TERM_DYNAMIC);
drh7b4fc6a2007-02-06 13:26:32 +0000935 exprAnalyze(pSrc, pWC, idxNew1);
drh17435752007-08-16 04:30:38 +0000936 pNewExpr2 = sqlite3PExpr(pParse, TK_LT, sqlite3ExprDup(db,pLeft), pStr2, 0);
drh9eb20282005-08-24 03:52:18 +0000937 idxNew2 = whereClauseInsert(pWC, pNewExpr2, TERM_VIRTUAL|TERM_DYNAMIC);
drh7b4fc6a2007-02-06 13:26:32 +0000938 exprAnalyze(pSrc, pWC, idxNew2);
drh9eb20282005-08-24 03:52:18 +0000939 pTerm = &pWC->a[idxTerm];
drhd2687b72005-08-12 22:56:09 +0000940 if( isComplete ){
drh9eb20282005-08-24 03:52:18 +0000941 pWC->a[idxNew1].iParent = idxTerm;
942 pWC->a[idxNew2].iParent = idxTerm;
drhd2687b72005-08-12 22:56:09 +0000943 pTerm->nChild = 2;
944 }
945 }
946#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
drh7f375902006-06-13 17:38:59 +0000947
948#ifndef SQLITE_OMIT_VIRTUALTABLE
949 /* Add a WO_MATCH auxiliary term to the constraint set if the
950 ** current expression is of the form: column MATCH expr.
951 ** This information is used by the xBestIndex methods of
952 ** virtual tables. The native query optimizer does not attempt
953 ** to do anything with MATCH functions.
954 */
955 if( isMatchOfColumn(pExpr) ){
956 int idxNew;
957 Expr *pRight, *pLeft;
958 WhereTerm *pNewTerm;
959 Bitmask prereqColumn, prereqExpr;
960
961 pRight = pExpr->pList->a[0].pExpr;
962 pLeft = pExpr->pList->a[1].pExpr;
963 prereqExpr = exprTableUsage(pMaskSet, pRight);
964 prereqColumn = exprTableUsage(pMaskSet, pLeft);
965 if( (prereqExpr & prereqColumn)==0 ){
drh1a90e092006-06-14 22:07:10 +0000966 Expr *pNewExpr;
danielk1977a1644fd2007-08-29 12:31:25 +0000967 pNewExpr = sqlite3Expr(db, TK_MATCH, 0, sqlite3ExprDup(db, pRight), 0);
drh1a90e092006-06-14 22:07:10 +0000968 idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
drh7f375902006-06-13 17:38:59 +0000969 pNewTerm = &pWC->a[idxNew];
970 pNewTerm->prereqRight = prereqExpr;
971 pNewTerm->leftCursor = pLeft->iTable;
972 pNewTerm->leftColumn = pLeft->iColumn;
973 pNewTerm->eOperator = WO_MATCH;
974 pNewTerm->iParent = idxTerm;
drhd2ca60d2006-06-27 02:36:58 +0000975 pTerm = &pWC->a[idxTerm];
drh7f375902006-06-13 17:38:59 +0000976 pTerm->nChild = 1;
977 pTerm->flags |= TERM_COPIED;
978 pNewTerm->prereqAll = pTerm->prereqAll;
979 }
980 }
981#endif /* SQLITE_OMIT_VIRTUALTABLE */
drhdafc0ce2008-04-17 19:14:02 +0000982
983 /* Prevent ON clause terms of a LEFT JOIN from being used to drive
984 ** an index for tables to the left of the join.
985 */
986 pTerm->prereqRight |= extraRight;
drh75897232000-05-29 14:26:00 +0000987}
988
drh7b4fc6a2007-02-06 13:26:32 +0000989/*
990** Return TRUE if any of the expressions in pList->a[iFirst...] contain
991** a reference to any table other than the iBase table.
992*/
993static int referencesOtherTables(
994 ExprList *pList, /* Search expressions in ths list */
995 ExprMaskSet *pMaskSet, /* Mapping from tables to bitmaps */
996 int iFirst, /* Be searching with the iFirst-th expression */
997 int iBase /* Ignore references to this table */
998){
999 Bitmask allowed = ~getMask(pMaskSet, iBase);
1000 while( iFirst<pList->nExpr ){
1001 if( (exprTableUsage(pMaskSet, pList->a[iFirst++].pExpr)&allowed)!=0 ){
1002 return 1;
1003 }
1004 }
1005 return 0;
1006}
1007
drh0fcef5e2005-07-19 17:38:22 +00001008
drh75897232000-05-29 14:26:00 +00001009/*
drh51669862004-12-18 18:40:26 +00001010** This routine decides if pIdx can be used to satisfy the ORDER BY
1011** clause. If it can, it returns 1. If pIdx cannot satisfy the
1012** ORDER BY clause, this routine returns 0.
1013**
1014** pOrderBy is an ORDER BY clause from a SELECT statement. pTab is the
1015** left-most table in the FROM clause of that same SELECT statement and
1016** the table has a cursor number of "base". pIdx is an index on pTab.
1017**
1018** nEqCol is the number of columns of pIdx that are used as equality
1019** constraints. Any of these columns may be missing from the ORDER BY
1020** clause and the match can still be a success.
1021**
drh51669862004-12-18 18:40:26 +00001022** All terms of the ORDER BY that match against the index must be either
1023** ASC or DESC. (Terms of the ORDER BY clause past the end of a UNIQUE
1024** index do not need to satisfy this constraint.) The *pbRev value is
1025** set to 1 if the ORDER BY clause is all DESC and it is set to 0 if
1026** the ORDER BY clause is all ASC.
1027*/
1028static int isSortingIndex(
1029 Parse *pParse, /* Parsing context */
drh7b4fc6a2007-02-06 13:26:32 +00001030 ExprMaskSet *pMaskSet, /* Mapping from table indices to bitmaps */
drh51669862004-12-18 18:40:26 +00001031 Index *pIdx, /* The index we are testing */
drh74161702006-02-24 02:53:49 +00001032 int base, /* Cursor number for the table to be sorted */
drh51669862004-12-18 18:40:26 +00001033 ExprList *pOrderBy, /* The ORDER BY clause */
1034 int nEqCol, /* Number of index columns with == constraints */
1035 int *pbRev /* Set to 1 if ORDER BY is DESC */
1036){
drhb46b5772005-08-29 16:40:52 +00001037 int i, j; /* Loop counters */
drh85eeb692005-12-21 03:16:42 +00001038 int sortOrder = 0; /* XOR of index and ORDER BY sort direction */
drhb46b5772005-08-29 16:40:52 +00001039 int nTerm; /* Number of ORDER BY terms */
1040 struct ExprList_item *pTerm; /* A term of the ORDER BY clause */
drh51669862004-12-18 18:40:26 +00001041 sqlite3 *db = pParse->db;
1042
1043 assert( pOrderBy!=0 );
1044 nTerm = pOrderBy->nExpr;
1045 assert( nTerm>0 );
1046
1047 /* Match terms of the ORDER BY clause against columns of
1048 ** the index.
drhcc192542006-12-20 03:24:19 +00001049 **
1050 ** Note that indices have pIdx->nColumn regular columns plus
1051 ** one additional column containing the rowid. The rowid column
1052 ** of the index is also allowed to match against the ORDER BY
1053 ** clause.
drh51669862004-12-18 18:40:26 +00001054 */
drhcc192542006-12-20 03:24:19 +00001055 for(i=j=0, pTerm=pOrderBy->a; j<nTerm && i<=pIdx->nColumn; i++){
drh51669862004-12-18 18:40:26 +00001056 Expr *pExpr; /* The expression of the ORDER BY pTerm */
1057 CollSeq *pColl; /* The collating sequence of pExpr */
drh85eeb692005-12-21 03:16:42 +00001058 int termSortOrder; /* Sort order for this term */
drhcc192542006-12-20 03:24:19 +00001059 int iColumn; /* The i-th column of the index. -1 for rowid */
1060 int iSortOrder; /* 1 for DESC, 0 for ASC on the i-th index term */
1061 const char *zColl; /* Name of the collating sequence for i-th index term */
drh51669862004-12-18 18:40:26 +00001062
1063 pExpr = pTerm->pExpr;
1064 if( pExpr->op!=TK_COLUMN || pExpr->iTable!=base ){
1065 /* Can not use an index sort on anything that is not a column in the
1066 ** left-most table of the FROM clause */
drh7b4fc6a2007-02-06 13:26:32 +00001067 break;
drh51669862004-12-18 18:40:26 +00001068 }
1069 pColl = sqlite3ExprCollSeq(pParse, pExpr);
drhcc192542006-12-20 03:24:19 +00001070 if( !pColl ){
1071 pColl = db->pDfltColl;
1072 }
1073 if( i<pIdx->nColumn ){
1074 iColumn = pIdx->aiColumn[i];
1075 if( iColumn==pIdx->pTable->iPKey ){
1076 iColumn = -1;
1077 }
1078 iSortOrder = pIdx->aSortOrder[i];
1079 zColl = pIdx->azColl[i];
1080 }else{
1081 iColumn = -1;
1082 iSortOrder = 0;
1083 zColl = pColl->zName;
1084 }
1085 if( pExpr->iColumn!=iColumn || sqlite3StrICmp(pColl->zName, zColl) ){
drh9012bcb2004-12-19 00:11:35 +00001086 /* Term j of the ORDER BY clause does not match column i of the index */
1087 if( i<nEqCol ){
drh51669862004-12-18 18:40:26 +00001088 /* If an index column that is constrained by == fails to match an
1089 ** ORDER BY term, that is OK. Just ignore that column of the index
1090 */
1091 continue;
1092 }else{
1093 /* If an index column fails to match and is not constrained by ==
1094 ** then the index cannot satisfy the ORDER BY constraint.
1095 */
1096 return 0;
1097 }
1098 }
danielk1977b3bf5562006-01-10 17:58:23 +00001099 assert( pIdx->aSortOrder!=0 );
drh85eeb692005-12-21 03:16:42 +00001100 assert( pTerm->sortOrder==0 || pTerm->sortOrder==1 );
drhcc192542006-12-20 03:24:19 +00001101 assert( iSortOrder==0 || iSortOrder==1 );
1102 termSortOrder = iSortOrder ^ pTerm->sortOrder;
drh51669862004-12-18 18:40:26 +00001103 if( i>nEqCol ){
drh85eeb692005-12-21 03:16:42 +00001104 if( termSortOrder!=sortOrder ){
drh51669862004-12-18 18:40:26 +00001105 /* Indices can only be used if all ORDER BY terms past the
1106 ** equality constraints are all either DESC or ASC. */
1107 return 0;
1108 }
1109 }else{
drh85eeb692005-12-21 03:16:42 +00001110 sortOrder = termSortOrder;
drh51669862004-12-18 18:40:26 +00001111 }
1112 j++;
1113 pTerm++;
drh7b4fc6a2007-02-06 13:26:32 +00001114 if( iColumn<0 && !referencesOtherTables(pOrderBy, pMaskSet, j, base) ){
drhcc192542006-12-20 03:24:19 +00001115 /* If the indexed column is the primary key and everything matches
drh7b4fc6a2007-02-06 13:26:32 +00001116 ** so far and none of the ORDER BY terms to the right reference other
1117 ** tables in the join, then we are assured that the index can be used
1118 ** to sort because the primary key is unique and so none of the other
1119 ** columns will make any difference
drhcc192542006-12-20 03:24:19 +00001120 */
1121 j = nTerm;
1122 }
drh51669862004-12-18 18:40:26 +00001123 }
1124
drhcc192542006-12-20 03:24:19 +00001125 *pbRev = sortOrder!=0;
drh8718f522005-08-13 16:13:04 +00001126 if( j>=nTerm ){
drhcc192542006-12-20 03:24:19 +00001127 /* All terms of the ORDER BY clause are covered by this index so
1128 ** this index can be used for sorting. */
1129 return 1;
1130 }
drh7b4fc6a2007-02-06 13:26:32 +00001131 if( pIdx->onError!=OE_None && i==pIdx->nColumn
1132 && !referencesOtherTables(pOrderBy, pMaskSet, j, base) ){
drhcc192542006-12-20 03:24:19 +00001133 /* All terms of this index match some prefix of the ORDER BY clause
drh7b4fc6a2007-02-06 13:26:32 +00001134 ** and the index is UNIQUE and no terms on the tail of the ORDER BY
1135 ** clause reference other tables in a join. If this is all true then
1136 ** the order by clause is superfluous. */
drh51669862004-12-18 18:40:26 +00001137 return 1;
1138 }
1139 return 0;
1140}
1141
1142/*
drhb6c29892004-11-22 19:12:19 +00001143** Check table to see if the ORDER BY clause in pOrderBy can be satisfied
1144** by sorting in order of ROWID. Return true if so and set *pbRev to be
1145** true for reverse ROWID and false for forward ROWID order.
1146*/
1147static int sortableByRowid(
1148 int base, /* Cursor number for table to be sorted */
1149 ExprList *pOrderBy, /* The ORDER BY clause */
drh7b4fc6a2007-02-06 13:26:32 +00001150 ExprMaskSet *pMaskSet, /* Mapping from tables to bitmaps */
drhb6c29892004-11-22 19:12:19 +00001151 int *pbRev /* Set to 1 if ORDER BY is DESC */
1152){
1153 Expr *p;
1154
1155 assert( pOrderBy!=0 );
1156 assert( pOrderBy->nExpr>0 );
1157 p = pOrderBy->a[0].pExpr;
drh7b4fc6a2007-02-06 13:26:32 +00001158 if( p->op==TK_COLUMN && p->iTable==base && p->iColumn==-1
1159 && !referencesOtherTables(pOrderBy, pMaskSet, 1, base) ){
drhb6c29892004-11-22 19:12:19 +00001160 *pbRev = pOrderBy->a[0].sortOrder;
1161 return 1;
1162 }
1163 return 0;
1164}
1165
drhfe05af82005-07-21 03:14:59 +00001166/*
drhb6fb62d2005-09-20 08:47:20 +00001167** Prepare a crude estimate of the logarithm of the input value.
drh28c4cf42005-07-27 20:41:43 +00001168** The results need not be exact. This is only used for estimating
1169** the total cost of performing operatings with O(logN) or O(NlogN)
1170** complexity. Because N is just a guess, it is no great tragedy if
1171** logN is a little off.
drh28c4cf42005-07-27 20:41:43 +00001172*/
1173static double estLog(double N){
drhb37df7b2005-10-13 02:09:49 +00001174 double logN = 1;
1175 double x = 10;
drh28c4cf42005-07-27 20:41:43 +00001176 while( N>x ){
drhb37df7b2005-10-13 02:09:49 +00001177 logN += 1;
drh28c4cf42005-07-27 20:41:43 +00001178 x *= 10;
1179 }
1180 return logN;
1181}
1182
drh6d209d82006-06-27 01:54:26 +00001183/*
1184** Two routines for printing the content of an sqlite3_index_info
1185** structure. Used for testing and debugging only. If neither
1186** SQLITE_TEST or SQLITE_DEBUG are defined, then these routines
1187** are no-ops.
1188*/
drh77a2a5e2007-04-06 01:04:39 +00001189#if !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(SQLITE_DEBUG)
drh6d209d82006-06-27 01:54:26 +00001190static void TRACE_IDX_INPUTS(sqlite3_index_info *p){
1191 int i;
mlcreech3a00f902008-03-04 17:45:01 +00001192 if( !sqlite3WhereTrace ) return;
drh6d209d82006-06-27 01:54:26 +00001193 for(i=0; i<p->nConstraint; i++){
1194 sqlite3DebugPrintf(" constraint[%d]: col=%d termid=%d op=%d usabled=%d\n",
1195 i,
1196 p->aConstraint[i].iColumn,
1197 p->aConstraint[i].iTermOffset,
1198 p->aConstraint[i].op,
1199 p->aConstraint[i].usable);
1200 }
1201 for(i=0; i<p->nOrderBy; i++){
1202 sqlite3DebugPrintf(" orderby[%d]: col=%d desc=%d\n",
1203 i,
1204 p->aOrderBy[i].iColumn,
1205 p->aOrderBy[i].desc);
1206 }
1207}
1208static void TRACE_IDX_OUTPUTS(sqlite3_index_info *p){
1209 int i;
mlcreech3a00f902008-03-04 17:45:01 +00001210 if( !sqlite3WhereTrace ) return;
drh6d209d82006-06-27 01:54:26 +00001211 for(i=0; i<p->nConstraint; i++){
1212 sqlite3DebugPrintf(" usage[%d]: argvIdx=%d omit=%d\n",
1213 i,
1214 p->aConstraintUsage[i].argvIndex,
1215 p->aConstraintUsage[i].omit);
1216 }
1217 sqlite3DebugPrintf(" idxNum=%d\n", p->idxNum);
1218 sqlite3DebugPrintf(" idxStr=%s\n", p->idxStr);
1219 sqlite3DebugPrintf(" orderByConsumed=%d\n", p->orderByConsumed);
1220 sqlite3DebugPrintf(" estimatedCost=%g\n", p->estimatedCost);
1221}
1222#else
1223#define TRACE_IDX_INPUTS(A)
1224#define TRACE_IDX_OUTPUTS(A)
1225#endif
1226
drh9eff6162006-06-12 21:59:13 +00001227#ifndef SQLITE_OMIT_VIRTUALTABLE
1228/*
drh7f375902006-06-13 17:38:59 +00001229** Compute the best index for a virtual table.
1230**
1231** The best index is computed by the xBestIndex method of the virtual
1232** table module. This routine is really just a wrapper that sets up
1233** the sqlite3_index_info structure that is used to communicate with
1234** xBestIndex.
1235**
1236** In a join, this routine might be called multiple times for the
1237** same virtual table. The sqlite3_index_info structure is created
1238** and initialized on the first invocation and reused on all subsequent
1239** invocations. The sqlite3_index_info structure is also used when
1240** code is generated to access the virtual table. The whereInfoDelete()
1241** routine takes care of freeing the sqlite3_index_info structure after
1242** everybody has finished with it.
drh9eff6162006-06-12 21:59:13 +00001243*/
1244static double bestVirtualIndex(
1245 Parse *pParse, /* The parsing context */
1246 WhereClause *pWC, /* The WHERE clause */
1247 struct SrcList_item *pSrc, /* The FROM clause term to search */
1248 Bitmask notReady, /* Mask of cursors that are not available */
1249 ExprList *pOrderBy, /* The order by clause */
1250 int orderByUsable, /* True if we can potential sort */
1251 sqlite3_index_info **ppIdxInfo /* Index information passed to xBestIndex */
1252){
1253 Table *pTab = pSrc->pTab;
1254 sqlite3_index_info *pIdxInfo;
1255 struct sqlite3_index_constraint *pIdxCons;
1256 struct sqlite3_index_orderby *pIdxOrderBy;
1257 struct sqlite3_index_constraint_usage *pUsage;
1258 WhereTerm *pTerm;
1259 int i, j;
1260 int nOrderBy;
danielk197774cdba42006-06-19 12:02:58 +00001261 int rc;
drh9eff6162006-06-12 21:59:13 +00001262
1263 /* If the sqlite3_index_info structure has not been previously
1264 ** allocated and initialized for this virtual table, then allocate
1265 ** and initialize it now
1266 */
1267 pIdxInfo = *ppIdxInfo;
1268 if( pIdxInfo==0 ){
1269 WhereTerm *pTerm;
1270 int nTerm;
drh4f0c5872007-03-26 22:05:01 +00001271 WHERETRACE(("Recomputing index info for %s...\n", pTab->zName));
drh9eff6162006-06-12 21:59:13 +00001272
1273 /* Count the number of possible WHERE clause constraints referring
1274 ** to this virtual table */
1275 for(i=nTerm=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
1276 if( pTerm->leftCursor != pSrc->iCursor ) continue;
drh981642f2008-04-19 14:40:43 +00001277 if( (pTerm->eOperator&(pTerm->eOperator-1))==0 );
1278 testcase( pTerm->eOperator==WO_IN );
1279 testcase( pTerm->eOperator==WO_ISNULL );
1280 if( pTerm->eOperator & (WO_IN|WO_ISNULL) ) continue;
drh9eff6162006-06-12 21:59:13 +00001281 nTerm++;
1282 }
1283
1284 /* If the ORDER BY clause contains only columns in the current
1285 ** virtual table then allocate space for the aOrderBy part of
1286 ** the sqlite3_index_info structure.
1287 */
1288 nOrderBy = 0;
1289 if( pOrderBy ){
1290 for(i=0; i<pOrderBy->nExpr; i++){
1291 Expr *pExpr = pOrderBy->a[i].pExpr;
1292 if( pExpr->op!=TK_COLUMN || pExpr->iTable!=pSrc->iCursor ) break;
1293 }
1294 if( i==pOrderBy->nExpr ){
1295 nOrderBy = pOrderBy->nExpr;
1296 }
1297 }
1298
1299 /* Allocate the sqlite3_index_info structure
1300 */
danielk197726783a52007-08-29 14:06:22 +00001301 pIdxInfo = sqlite3DbMallocZero(pParse->db, sizeof(*pIdxInfo)
drh9eff6162006-06-12 21:59:13 +00001302 + (sizeof(*pIdxCons) + sizeof(*pUsage))*nTerm
1303 + sizeof(*pIdxOrderBy)*nOrderBy );
1304 if( pIdxInfo==0 ){
1305 sqlite3ErrorMsg(pParse, "out of memory");
1306 return 0.0;
1307 }
1308 *ppIdxInfo = pIdxInfo;
1309
1310 /* Initialize the structure. The sqlite3_index_info structure contains
1311 ** many fields that are declared "const" to prevent xBestIndex from
1312 ** changing them. We have to do some funky casting in order to
1313 ** initialize those fields.
1314 */
1315 pIdxCons = (struct sqlite3_index_constraint*)&pIdxInfo[1];
1316 pIdxOrderBy = (struct sqlite3_index_orderby*)&pIdxCons[nTerm];
1317 pUsage = (struct sqlite3_index_constraint_usage*)&pIdxOrderBy[nOrderBy];
1318 *(int*)&pIdxInfo->nConstraint = nTerm;
1319 *(int*)&pIdxInfo->nOrderBy = nOrderBy;
1320 *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint = pIdxCons;
1321 *(struct sqlite3_index_orderby**)&pIdxInfo->aOrderBy = pIdxOrderBy;
1322 *(struct sqlite3_index_constraint_usage**)&pIdxInfo->aConstraintUsage =
1323 pUsage;
1324
1325 for(i=j=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
1326 if( pTerm->leftCursor != pSrc->iCursor ) continue;
drh981642f2008-04-19 14:40:43 +00001327 if( (pTerm->eOperator&(pTerm->eOperator-1))==0 );
1328 testcase( pTerm->eOperator==WO_IN );
1329 testcase( pTerm->eOperator==WO_ISNULL );
1330 if( pTerm->eOperator & (WO_IN|WO_ISNULL) ) continue;
drh9eff6162006-06-12 21:59:13 +00001331 pIdxCons[j].iColumn = pTerm->leftColumn;
1332 pIdxCons[j].iTermOffset = i;
1333 pIdxCons[j].op = pTerm->eOperator;
drh7f375902006-06-13 17:38:59 +00001334 /* The direct assignment in the previous line is possible only because
1335 ** the WO_ and SQLITE_INDEX_CONSTRAINT_ codes are identical. The
1336 ** following asserts verify this fact. */
drh9eff6162006-06-12 21:59:13 +00001337 assert( WO_EQ==SQLITE_INDEX_CONSTRAINT_EQ );
1338 assert( WO_LT==SQLITE_INDEX_CONSTRAINT_LT );
1339 assert( WO_LE==SQLITE_INDEX_CONSTRAINT_LE );
1340 assert( WO_GT==SQLITE_INDEX_CONSTRAINT_GT );
1341 assert( WO_GE==SQLITE_INDEX_CONSTRAINT_GE );
drh7f375902006-06-13 17:38:59 +00001342 assert( WO_MATCH==SQLITE_INDEX_CONSTRAINT_MATCH );
1343 assert( pTerm->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE|WO_MATCH) );
drh9eff6162006-06-12 21:59:13 +00001344 j++;
1345 }
1346 for(i=0; i<nOrderBy; i++){
1347 Expr *pExpr = pOrderBy->a[i].pExpr;
1348 pIdxOrderBy[i].iColumn = pExpr->iColumn;
1349 pIdxOrderBy[i].desc = pOrderBy->a[i].sortOrder;
1350 }
1351 }
1352
drh7f375902006-06-13 17:38:59 +00001353 /* At this point, the sqlite3_index_info structure that pIdxInfo points
1354 ** to will have been initialized, either during the current invocation or
1355 ** during some prior invocation. Now we just have to customize the
1356 ** details of pIdxInfo for the current invocation and pass it to
1357 ** xBestIndex.
1358 */
1359
danielk1977935ed5e2007-03-30 09:13:13 +00001360 /* The module name must be defined. Also, by this point there must
1361 ** be a pointer to an sqlite3_vtab structure. Otherwise
1362 ** sqlite3ViewGetColumnNames() would have picked up the error.
1363 */
drh9eff6162006-06-12 21:59:13 +00001364 assert( pTab->azModuleArg && pTab->azModuleArg[0] );
danielk1977935ed5e2007-03-30 09:13:13 +00001365 assert( pTab->pVtab );
1366#if 0
drh9eff6162006-06-12 21:59:13 +00001367 if( pTab->pVtab==0 ){
1368 sqlite3ErrorMsg(pParse, "undefined module %s for table %s",
1369 pTab->azModuleArg[0], pTab->zName);
1370 return 0.0;
1371 }
danielk1977935ed5e2007-03-30 09:13:13 +00001372#endif
drh9eff6162006-06-12 21:59:13 +00001373
1374 /* Set the aConstraint[].usable fields and initialize all
drh7f375902006-06-13 17:38:59 +00001375 ** output variables to zero.
1376 **
1377 ** aConstraint[].usable is true for constraints where the right-hand
1378 ** side contains only references to tables to the left of the current
1379 ** table. In other words, if the constraint is of the form:
1380 **
1381 ** column = expr
1382 **
1383 ** and we are evaluating a join, then the constraint on column is
1384 ** only valid if all tables referenced in expr occur to the left
1385 ** of the table containing column.
1386 **
1387 ** The aConstraints[] array contains entries for all constraints
1388 ** on the current table. That way we only have to compute it once
1389 ** even though we might try to pick the best index multiple times.
1390 ** For each attempt at picking an index, the order of tables in the
1391 ** join might be different so we have to recompute the usable flag
1392 ** each time.
drh9eff6162006-06-12 21:59:13 +00001393 */
1394 pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint;
1395 pUsage = pIdxInfo->aConstraintUsage;
1396 for(i=0; i<pIdxInfo->nConstraint; i++, pIdxCons++){
1397 j = pIdxCons->iTermOffset;
1398 pTerm = &pWC->a[j];
1399 pIdxCons->usable = (pTerm->prereqRight & notReady)==0;
1400 }
1401 memset(pUsage, 0, sizeof(pUsage[0])*pIdxInfo->nConstraint);
drh4be8b512006-06-13 23:51:34 +00001402 if( pIdxInfo->needToFreeIdxStr ){
1403 sqlite3_free(pIdxInfo->idxStr);
1404 }
1405 pIdxInfo->idxStr = 0;
1406 pIdxInfo->idxNum = 0;
1407 pIdxInfo->needToFreeIdxStr = 0;
drh9eff6162006-06-12 21:59:13 +00001408 pIdxInfo->orderByConsumed = 0;
danielk197793626f42006-06-20 13:07:27 +00001409 pIdxInfo->estimatedCost = SQLITE_BIG_DBL / 2.0;
drh9eff6162006-06-12 21:59:13 +00001410 nOrderBy = pIdxInfo->nOrderBy;
1411 if( pIdxInfo->nOrderBy && !orderByUsable ){
drha967e882006-06-13 01:04:52 +00001412 *(int*)&pIdxInfo->nOrderBy = 0;
drh9eff6162006-06-12 21:59:13 +00001413 }
danielk197774cdba42006-06-19 12:02:58 +00001414
drh7e8b8482008-01-23 03:03:05 +00001415 (void)sqlite3SafetyOff(pParse->db);
drh4f0c5872007-03-26 22:05:01 +00001416 WHERETRACE(("xBestIndex for %s\n", pTab->zName));
drh6d209d82006-06-27 01:54:26 +00001417 TRACE_IDX_INPUTS(pIdxInfo);
danielk1977be718892006-06-23 08:05:19 +00001418 rc = pTab->pVtab->pModule->xBestIndex(pTab->pVtab, pIdxInfo);
drh6d209d82006-06-27 01:54:26 +00001419 TRACE_IDX_OUTPUTS(pIdxInfo);
danielk197739359dc2008-03-17 09:36:44 +00001420 (void)sqlite3SafetyOn(pParse->db);
1421
1422 for(i=0; i<pIdxInfo->nConstraint; i++){
1423 if( !pIdxInfo->aConstraint[i].usable && pUsage[i].argvIndex>0 ){
1424 sqlite3ErrorMsg(pParse,
1425 "table %s: xBestIndex returned an invalid plan", pTab->zName);
1426 return 0.0;
1427 }
1428 }
1429
danielk197774cdba42006-06-19 12:02:58 +00001430 if( rc!=SQLITE_OK ){
danielk1977be718892006-06-23 08:05:19 +00001431 if( rc==SQLITE_NOMEM ){
drh17435752007-08-16 04:30:38 +00001432 pParse->db->mallocFailed = 1;
danielk1977be718892006-06-23 08:05:19 +00001433 }else {
1434 sqlite3ErrorMsg(pParse, "%s", sqlite3ErrStr(rc));
1435 }
danielk197774cdba42006-06-19 12:02:58 +00001436 }
drha967e882006-06-13 01:04:52 +00001437 *(int*)&pIdxInfo->nOrderBy = nOrderBy;
danielk19778efe5412007-03-02 08:12:22 +00001438
drh9eff6162006-06-12 21:59:13 +00001439 return pIdxInfo->estimatedCost;
1440}
1441#endif /* SQLITE_OMIT_VIRTUALTABLE */
1442
drh28c4cf42005-07-27 20:41:43 +00001443/*
drh51147ba2005-07-23 22:59:55 +00001444** Find the best index for accessing a particular table. Return a pointer
1445** to the index, flags that describe how the index should be used, the
drha6110402005-07-28 20:51:19 +00001446** number of equality constraints, and the "cost" for this index.
drh51147ba2005-07-23 22:59:55 +00001447**
1448** The lowest cost index wins. The cost is an estimate of the amount of
1449** CPU and disk I/O need to process the request using the selected index.
1450** Factors that influence cost include:
1451**
1452** * The estimated number of rows that will be retrieved. (The
1453** fewer the better.)
1454**
1455** * Whether or not sorting must occur.
1456**
1457** * Whether or not there must be separate lookups in the
1458** index and in the main table.
1459**
drhfe05af82005-07-21 03:14:59 +00001460*/
1461static double bestIndex(
1462 Parse *pParse, /* The parsing context */
1463 WhereClause *pWC, /* The WHERE clause */
1464 struct SrcList_item *pSrc, /* The FROM clause term to search */
1465 Bitmask notReady, /* Mask of cursors that are not available */
1466 ExprList *pOrderBy, /* The order by clause */
1467 Index **ppIndex, /* Make *ppIndex point to the best index */
drh51147ba2005-07-23 22:59:55 +00001468 int *pFlags, /* Put flags describing this choice in *pFlags */
1469 int *pnEq /* Put the number of == or IN constraints here */
drhfe05af82005-07-21 03:14:59 +00001470){
1471 WhereTerm *pTerm;
drh51147ba2005-07-23 22:59:55 +00001472 Index *bestIdx = 0; /* Index that gives the lowest cost */
drhb37df7b2005-10-13 02:09:49 +00001473 double lowestCost; /* The cost of using bestIdx */
drh51147ba2005-07-23 22:59:55 +00001474 int bestFlags = 0; /* Flags associated with bestIdx */
1475 int bestNEq = 0; /* Best value for nEq */
1476 int iCur = pSrc->iCursor; /* The cursor of the table to be accessed */
1477 Index *pProbe; /* An index we are evaluating */
1478 int rev; /* True to scan in reverse order */
1479 int flags; /* Flags associated with pProbe */
1480 int nEq; /* Number of == or IN constraints */
drhc49de5d2007-01-19 01:06:01 +00001481 int eqTermMask; /* Mask of valid equality operators */
drh51147ba2005-07-23 22:59:55 +00001482 double cost; /* Cost of using pProbe */
drhfe05af82005-07-21 03:14:59 +00001483
shane7bc71e52008-05-28 18:01:44 +00001484 WHERETRACE(("bestIndex: tbl=%s notReady=%llx\n", pSrc->pTab->zName, notReady));
drhb37df7b2005-10-13 02:09:49 +00001485 lowestCost = SQLITE_BIG_DBL;
drh4dd238a2006-03-28 23:55:57 +00001486 pProbe = pSrc->pTab->pIndex;
1487
1488 /* If the table has no indices and there are no terms in the where
1489 ** clause that refer to the ROWID, then we will never be able to do
1490 ** anything other than a full table scan on this table. We might as
1491 ** well put it first in the join order. That way, perhaps it can be
1492 ** referenced by other tables in the join.
1493 */
1494 if( pProbe==0 &&
1495 findTerm(pWC, iCur, -1, 0, WO_EQ|WO_IN|WO_LT|WO_LE|WO_GT|WO_GE,0)==0 &&
drh7b4fc6a2007-02-06 13:26:32 +00001496 (pOrderBy==0 || !sortableByRowid(iCur, pOrderBy, pWC->pMaskSet, &rev)) ){
drh4dd238a2006-03-28 23:55:57 +00001497 *pFlags = 0;
1498 *ppIndex = 0;
1499 *pnEq = 0;
1500 return 0.0;
1501 }
drh51147ba2005-07-23 22:59:55 +00001502
1503 /* Check for a rowid=EXPR or rowid IN (...) constraints
drhfe05af82005-07-21 03:14:59 +00001504 */
1505 pTerm = findTerm(pWC, iCur, -1, notReady, WO_EQ|WO_IN, 0);
1506 if( pTerm ){
drha6110402005-07-28 20:51:19 +00001507 Expr *pExpr;
drhfe05af82005-07-21 03:14:59 +00001508 *ppIndex = 0;
drh51147ba2005-07-23 22:59:55 +00001509 bestFlags = WHERE_ROWID_EQ;
drhb52076c2006-01-23 13:22:09 +00001510 if( pTerm->eOperator & WO_EQ ){
drh28c4cf42005-07-27 20:41:43 +00001511 /* Rowid== is always the best pick. Look no further. Because only
1512 ** a single row is generated, output is always in sorted order */
drh943af3c2005-07-29 19:43:58 +00001513 *pFlags = WHERE_ROWID_EQ | WHERE_UNIQUE;
drh51147ba2005-07-23 22:59:55 +00001514 *pnEq = 1;
drh4f0c5872007-03-26 22:05:01 +00001515 WHERETRACE(("... best is rowid\n"));
drh51147ba2005-07-23 22:59:55 +00001516 return 0.0;
drha6110402005-07-28 20:51:19 +00001517 }else if( (pExpr = pTerm->pExpr)->pList!=0 ){
drh28c4cf42005-07-27 20:41:43 +00001518 /* Rowid IN (LIST): cost is NlogN where N is the number of list
1519 ** elements. */
drha6110402005-07-28 20:51:19 +00001520 lowestCost = pExpr->pList->nExpr;
drh28c4cf42005-07-27 20:41:43 +00001521 lowestCost *= estLog(lowestCost);
drhfe05af82005-07-21 03:14:59 +00001522 }else{
drh28c4cf42005-07-27 20:41:43 +00001523 /* Rowid IN (SELECT): cost is NlogN where N is the number of rows
1524 ** in the result of the inner select. We have no way to estimate
1525 ** that value so make a wild guess. */
drhb37df7b2005-10-13 02:09:49 +00001526 lowestCost = 200;
drhfe05af82005-07-21 03:14:59 +00001527 }
drh4f0c5872007-03-26 22:05:01 +00001528 WHERETRACE(("... rowid IN cost: %.9g\n", lowestCost));
drhfe05af82005-07-21 03:14:59 +00001529 }
1530
drh28c4cf42005-07-27 20:41:43 +00001531 /* Estimate the cost of a table scan. If we do not know how many
1532 ** entries are in the table, use 1 million as a guess.
drhfe05af82005-07-21 03:14:59 +00001533 */
drhb37df7b2005-10-13 02:09:49 +00001534 cost = pProbe ? pProbe->aiRowEst[0] : 1000000;
drh4f0c5872007-03-26 22:05:01 +00001535 WHERETRACE(("... table scan base cost: %.9g\n", cost));
drh28c4cf42005-07-27 20:41:43 +00001536 flags = WHERE_ROWID_RANGE;
1537
1538 /* Check for constraints on a range of rowids in a table scan.
1539 */
drhfe05af82005-07-21 03:14:59 +00001540 pTerm = findTerm(pWC, iCur, -1, notReady, WO_LT|WO_LE|WO_GT|WO_GE, 0);
1541 if( pTerm ){
drh51147ba2005-07-23 22:59:55 +00001542 if( findTerm(pWC, iCur, -1, notReady, WO_LT|WO_LE, 0) ){
1543 flags |= WHERE_TOP_LIMIT;
drhb37df7b2005-10-13 02:09:49 +00001544 cost /= 3; /* Guess that rowid<EXPR eliminates two-thirds or rows */
drhfe05af82005-07-21 03:14:59 +00001545 }
drh51147ba2005-07-23 22:59:55 +00001546 if( findTerm(pWC, iCur, -1, notReady, WO_GT|WO_GE, 0) ){
1547 flags |= WHERE_BTM_LIMIT;
drhb37df7b2005-10-13 02:09:49 +00001548 cost /= 3; /* Guess that rowid>EXPR eliminates two-thirds of rows */
drhfe05af82005-07-21 03:14:59 +00001549 }
drh4f0c5872007-03-26 22:05:01 +00001550 WHERETRACE(("... rowid range reduces cost to %.9g\n", cost));
drh51147ba2005-07-23 22:59:55 +00001551 }else{
1552 flags = 0;
1553 }
drh28c4cf42005-07-27 20:41:43 +00001554
1555 /* If the table scan does not satisfy the ORDER BY clause, increase
1556 ** the cost by NlogN to cover the expense of sorting. */
1557 if( pOrderBy ){
drh7b4fc6a2007-02-06 13:26:32 +00001558 if( sortableByRowid(iCur, pOrderBy, pWC->pMaskSet, &rev) ){
drh28c4cf42005-07-27 20:41:43 +00001559 flags |= WHERE_ORDERBY|WHERE_ROWID_RANGE;
1560 if( rev ){
1561 flags |= WHERE_REVERSE;
1562 }
1563 }else{
1564 cost += cost*estLog(cost);
drh4f0c5872007-03-26 22:05:01 +00001565 WHERETRACE(("... sorting increases cost to %.9g\n", cost));
drh51147ba2005-07-23 22:59:55 +00001566 }
drh51147ba2005-07-23 22:59:55 +00001567 }
1568 if( cost<lowestCost ){
1569 lowestCost = cost;
drhfe05af82005-07-21 03:14:59 +00001570 bestFlags = flags;
1571 }
1572
drhc49de5d2007-01-19 01:06:01 +00001573 /* If the pSrc table is the right table of a LEFT JOIN then we may not
1574 ** use an index to satisfy IS NULL constraints on that table. This is
1575 ** because columns might end up being NULL if the table does not match -
1576 ** a circumstance which the index cannot help us discover. Ticket #2177.
1577 */
1578 if( (pSrc->jointype & JT_LEFT)!=0 ){
1579 eqTermMask = WO_EQ|WO_IN;
1580 }else{
1581 eqTermMask = WO_EQ|WO_IN|WO_ISNULL;
1582 }
1583
drhfe05af82005-07-21 03:14:59 +00001584 /* Look at each index.
1585 */
drh51147ba2005-07-23 22:59:55 +00001586 for(; pProbe; pProbe=pProbe->pNext){
1587 int i; /* Loop counter */
drhb37df7b2005-10-13 02:09:49 +00001588 double inMultiplier = 1;
drh51147ba2005-07-23 22:59:55 +00001589
drh4f0c5872007-03-26 22:05:01 +00001590 WHERETRACE(("... index %s:\n", pProbe->zName));
drhfe05af82005-07-21 03:14:59 +00001591
1592 /* Count the number of columns in the index that are satisfied
1593 ** by x=EXPR constraints or x IN (...) constraints.
1594 */
drh51147ba2005-07-23 22:59:55 +00001595 flags = 0;
drhfe05af82005-07-21 03:14:59 +00001596 for(i=0; i<pProbe->nColumn; i++){
1597 int j = pProbe->aiColumn[i];
drhc49de5d2007-01-19 01:06:01 +00001598 pTerm = findTerm(pWC, iCur, j, notReady, eqTermMask, pProbe);
drhfe05af82005-07-21 03:14:59 +00001599 if( pTerm==0 ) break;
drh51147ba2005-07-23 22:59:55 +00001600 flags |= WHERE_COLUMN_EQ;
drhb52076c2006-01-23 13:22:09 +00001601 if( pTerm->eOperator & WO_IN ){
drha6110402005-07-28 20:51:19 +00001602 Expr *pExpr = pTerm->pExpr;
drh51147ba2005-07-23 22:59:55 +00001603 flags |= WHERE_COLUMN_IN;
drha6110402005-07-28 20:51:19 +00001604 if( pExpr->pSelect!=0 ){
drhffe0f892006-05-11 13:26:25 +00001605 inMultiplier *= 25;
drha6110402005-07-28 20:51:19 +00001606 }else if( pExpr->pList!=0 ){
drhb37df7b2005-10-13 02:09:49 +00001607 inMultiplier *= pExpr->pList->nExpr + 1;
drhfe05af82005-07-21 03:14:59 +00001608 }
1609 }
1610 }
drh28c4cf42005-07-27 20:41:43 +00001611 cost = pProbe->aiRowEst[i] * inMultiplier * estLog(inMultiplier);
drh51147ba2005-07-23 22:59:55 +00001612 nEq = i;
drh943af3c2005-07-29 19:43:58 +00001613 if( pProbe->onError!=OE_None && (flags & WHERE_COLUMN_IN)==0
1614 && nEq==pProbe->nColumn ){
1615 flags |= WHERE_UNIQUE;
1616 }
drh8e70e342007-09-13 17:54:40 +00001617 WHERETRACE(("...... nEq=%d inMult=%.9g cost=%.9g\n",nEq,inMultiplier,cost));
drhfe05af82005-07-21 03:14:59 +00001618
drh51147ba2005-07-23 22:59:55 +00001619 /* Look for range constraints
drhfe05af82005-07-21 03:14:59 +00001620 */
drh51147ba2005-07-23 22:59:55 +00001621 if( nEq<pProbe->nColumn ){
1622 int j = pProbe->aiColumn[nEq];
1623 pTerm = findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE|WO_GT|WO_GE, pProbe);
1624 if( pTerm ){
drha6110402005-07-28 20:51:19 +00001625 flags |= WHERE_COLUMN_RANGE;
drh51147ba2005-07-23 22:59:55 +00001626 if( findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE, pProbe) ){
1627 flags |= WHERE_TOP_LIMIT;
drhb37df7b2005-10-13 02:09:49 +00001628 cost /= 3;
drh51147ba2005-07-23 22:59:55 +00001629 }
1630 if( findTerm(pWC, iCur, j, notReady, WO_GT|WO_GE, pProbe) ){
1631 flags |= WHERE_BTM_LIMIT;
drhb37df7b2005-10-13 02:09:49 +00001632 cost /= 3;
drh51147ba2005-07-23 22:59:55 +00001633 }
drh4f0c5872007-03-26 22:05:01 +00001634 WHERETRACE(("...... range reduces cost to %.9g\n", cost));
drh51147ba2005-07-23 22:59:55 +00001635 }
1636 }
1637
drh28c4cf42005-07-27 20:41:43 +00001638 /* Add the additional cost of sorting if that is a factor.
drh51147ba2005-07-23 22:59:55 +00001639 */
drh28c4cf42005-07-27 20:41:43 +00001640 if( pOrderBy ){
1641 if( (flags & WHERE_COLUMN_IN)==0 &&
drh7b4fc6a2007-02-06 13:26:32 +00001642 isSortingIndex(pParse,pWC->pMaskSet,pProbe,iCur,pOrderBy,nEq,&rev) ){
drh28c4cf42005-07-27 20:41:43 +00001643 if( flags==0 ){
1644 flags = WHERE_COLUMN_RANGE;
1645 }
1646 flags |= WHERE_ORDERBY;
1647 if( rev ){
1648 flags |= WHERE_REVERSE;
1649 }
1650 }else{
1651 cost += cost*estLog(cost);
drh4f0c5872007-03-26 22:05:01 +00001652 WHERETRACE(("...... orderby increases cost to %.9g\n", cost));
drh51147ba2005-07-23 22:59:55 +00001653 }
drhfe05af82005-07-21 03:14:59 +00001654 }
1655
1656 /* Check to see if we can get away with using just the index without
drh51147ba2005-07-23 22:59:55 +00001657 ** ever reading the table. If that is the case, then halve the
1658 ** cost of this index.
drhfe05af82005-07-21 03:14:59 +00001659 */
drh51147ba2005-07-23 22:59:55 +00001660 if( flags && pSrc->colUsed < (((Bitmask)1)<<(BMS-1)) ){
drhfe05af82005-07-21 03:14:59 +00001661 Bitmask m = pSrc->colUsed;
1662 int j;
1663 for(j=0; j<pProbe->nColumn; j++){
1664 int x = pProbe->aiColumn[j];
1665 if( x<BMS-1 ){
1666 m &= ~(((Bitmask)1)<<x);
1667 }
1668 }
1669 if( m==0 ){
1670 flags |= WHERE_IDX_ONLY;
drhb37df7b2005-10-13 02:09:49 +00001671 cost /= 2;
drh4f0c5872007-03-26 22:05:01 +00001672 WHERETRACE(("...... idx-only reduces cost to %.9g\n", cost));
drhfe05af82005-07-21 03:14:59 +00001673 }
1674 }
1675
drh51147ba2005-07-23 22:59:55 +00001676 /* If this index has achieved the lowest cost so far, then use it.
drhfe05af82005-07-21 03:14:59 +00001677 */
drh8e70e342007-09-13 17:54:40 +00001678 if( flags && cost < lowestCost ){
drhfe05af82005-07-21 03:14:59 +00001679 bestIdx = pProbe;
drh51147ba2005-07-23 22:59:55 +00001680 lowestCost = cost;
drhfe05af82005-07-21 03:14:59 +00001681 bestFlags = flags;
drh51147ba2005-07-23 22:59:55 +00001682 bestNEq = nEq;
drhfe05af82005-07-21 03:14:59 +00001683 }
1684 }
1685
drhfe05af82005-07-21 03:14:59 +00001686 /* Report the best result
1687 */
1688 *ppIndex = bestIdx;
drh4f0c5872007-03-26 22:05:01 +00001689 WHERETRACE(("best index is %s, cost=%.9g, flags=%x, nEq=%d\n",
drh51147ba2005-07-23 22:59:55 +00001690 bestIdx ? bestIdx->zName : "(none)", lowestCost, bestFlags, bestNEq));
drhf2d315d2007-01-25 16:56:06 +00001691 *pFlags = bestFlags | eqTermMask;
drh51147ba2005-07-23 22:59:55 +00001692 *pnEq = bestNEq;
1693 return lowestCost;
drhfe05af82005-07-21 03:14:59 +00001694}
1695
drhb6c29892004-11-22 19:12:19 +00001696
1697/*
drh2ffb1182004-07-19 19:14:01 +00001698** Disable a term in the WHERE clause. Except, do not disable the term
1699** if it controls a LEFT OUTER JOIN and it did not originate in the ON
1700** or USING clause of that join.
1701**
1702** Consider the term t2.z='ok' in the following queries:
1703**
1704** (1) SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x WHERE t2.z='ok'
1705** (2) SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x AND t2.z='ok'
1706** (3) SELECT * FROM t1, t2 WHERE t1.a=t2.x AND t2.z='ok'
1707**
drh23bf66d2004-12-14 03:34:34 +00001708** The t2.z='ok' is disabled in the in (2) because it originates
drh2ffb1182004-07-19 19:14:01 +00001709** in the ON clause. The term is disabled in (3) because it is not part
1710** of a LEFT OUTER JOIN. In (1), the term is not disabled.
1711**
1712** Disabling a term causes that term to not be tested in the inner loop
drhb6fb62d2005-09-20 08:47:20 +00001713** of the join. Disabling is an optimization. When terms are satisfied
1714** by indices, we disable them to prevent redundant tests in the inner
1715** loop. We would get the correct results if nothing were ever disabled,
1716** but joins might run a little slower. The trick is to disable as much
1717** as we can without disabling too much. If we disabled in (1), we'd get
1718** the wrong answer. See ticket #813.
drh2ffb1182004-07-19 19:14:01 +00001719*/
drh0fcef5e2005-07-19 17:38:22 +00001720static void disableTerm(WhereLevel *pLevel, WhereTerm *pTerm){
1721 if( pTerm
1722 && (pTerm->flags & TERM_CODED)==0
1723 && (pLevel->iLeftJoin==0 || ExprHasProperty(pTerm->pExpr, EP_FromJoin))
1724 ){
1725 pTerm->flags |= TERM_CODED;
drh45b1ee42005-08-02 17:48:22 +00001726 if( pTerm->iParent>=0 ){
1727 WhereTerm *pOther = &pTerm->pWC->a[pTerm->iParent];
1728 if( (--pOther->nChild)==0 ){
drhed378002005-07-28 23:12:08 +00001729 disableTerm(pLevel, pOther);
1730 }
drh0fcef5e2005-07-19 17:38:22 +00001731 }
drh2ffb1182004-07-19 19:14:01 +00001732 }
1733}
1734
1735/*
danielk1977b790c6c2008-04-18 10:25:24 +00001736** Apply the affinities associated with the first n columns of index
1737** pIdx to the values in the n registers starting at base.
drh94a11212004-09-25 13:12:14 +00001738*/
danielk1977b790c6c2008-04-18 10:25:24 +00001739static void codeApplyAffinity(Parse *pParse, int base, int n, Index *pIdx){
1740 if( n>0 ){
1741 Vdbe *v = pParse->pVdbe;
1742 assert( v!=0 );
1743 sqlite3VdbeAddOp2(v, OP_Affinity, base, n);
1744 sqlite3IndexAffinityStr(v, pIdx);
1745 sqlite3ExprCacheAffinityChange(pParse, base, n);
1746 }
drh94a11212004-09-25 13:12:14 +00001747}
1748
drhe8b97272005-07-19 22:22:12 +00001749
1750/*
drh51147ba2005-07-23 22:59:55 +00001751** Generate code for a single equality term of the WHERE clause. An equality
1752** term can be either X=expr or X IN (...). pTerm is the term to be
1753** coded.
1754**
drh1db639c2008-01-17 02:36:28 +00001755** The current value for the constraint is left in register iReg.
drh51147ba2005-07-23 22:59:55 +00001756**
1757** For a constraint of the form X=expr, the expression is evaluated and its
1758** result is left on the stack. For constraints of the form X IN (...)
1759** this routine sets up a loop that will iterate over all values of X.
drh94a11212004-09-25 13:12:14 +00001760*/
drh678ccce2008-03-31 18:19:54 +00001761static int codeEqualityTerm(
drh94a11212004-09-25 13:12:14 +00001762 Parse *pParse, /* The parsing context */
drhe23399f2005-07-22 00:31:39 +00001763 WhereTerm *pTerm, /* The term of the WHERE clause to be coded */
drh1db639c2008-01-17 02:36:28 +00001764 WhereLevel *pLevel, /* When level of the FROM clause we are working on */
drh678ccce2008-03-31 18:19:54 +00001765 int iTarget /* Attempt to leave results in this register */
drh94a11212004-09-25 13:12:14 +00001766){
drh0fcef5e2005-07-19 17:38:22 +00001767 Expr *pX = pTerm->pExpr;
drh50b39962006-10-28 00:28:09 +00001768 Vdbe *v = pParse->pVdbe;
drh678ccce2008-03-31 18:19:54 +00001769 int iReg; /* Register holding results */
drh1db639c2008-01-17 02:36:28 +00001770
drh678ccce2008-03-31 18:19:54 +00001771 if( iTarget<=0 ){
1772 iReg = iTarget = sqlite3GetTempReg(pParse);
1773 }
drh50b39962006-10-28 00:28:09 +00001774 if( pX->op==TK_EQ ){
drh678ccce2008-03-31 18:19:54 +00001775 iReg = sqlite3ExprCodeTarget(pParse, pX->pRight, iTarget);
drh50b39962006-10-28 00:28:09 +00001776 }else if( pX->op==TK_ISNULL ){
drh678ccce2008-03-31 18:19:54 +00001777 iReg = iTarget;
drh1db639c2008-01-17 02:36:28 +00001778 sqlite3VdbeAddOp2(v, OP_Null, 0, iReg);
danielk1977b3bce662005-01-29 08:32:43 +00001779#ifndef SQLITE_OMIT_SUBQUERY
drh94a11212004-09-25 13:12:14 +00001780 }else{
danielk19779a96b662007-11-29 17:05:18 +00001781 int eType;
danielk1977b3bce662005-01-29 08:32:43 +00001782 int iTab;
drh72e8fa42007-03-28 14:30:06 +00001783 struct InLoop *pIn;
danielk1977b3bce662005-01-29 08:32:43 +00001784
drh50b39962006-10-28 00:28:09 +00001785 assert( pX->op==TK_IN );
drh678ccce2008-03-31 18:19:54 +00001786 iReg = iTarget;
danielk19779a96b662007-11-29 17:05:18 +00001787 eType = sqlite3FindInIndex(pParse, pX, 1);
danielk1977b3bce662005-01-29 08:32:43 +00001788 iTab = pX->iTable;
drh66a51672008-01-03 00:01:23 +00001789 sqlite3VdbeAddOp2(v, OP_Rewind, iTab, 0);
drhd4e70eb2008-01-02 00:34:36 +00001790 VdbeComment((v, "%.*s", pX->span.n, pX->span.z));
drh72e8fa42007-03-28 14:30:06 +00001791 if( pLevel->nIn==0 ){
1792 pLevel->nxt = sqlite3VdbeMakeLabel(v);
1793 }
drhe23399f2005-07-22 00:31:39 +00001794 pLevel->nIn++;
drh17435752007-08-16 04:30:38 +00001795 pLevel->aInLoop = sqlite3DbReallocOrFree(pParse->db, pLevel->aInLoop,
drh72e8fa42007-03-28 14:30:06 +00001796 sizeof(pLevel->aInLoop[0])*pLevel->nIn);
1797 pIn = pLevel->aInLoop;
1798 if( pIn ){
1799 pIn += pLevel->nIn - 1;
1800 pIn->iCur = iTab;
drh1db639c2008-01-17 02:36:28 +00001801 if( eType==IN_INDEX_ROWID ){
1802 pIn->topAddr = sqlite3VdbeAddOp2(v, OP_Rowid, iTab, iReg);
1803 }else{
1804 pIn->topAddr = sqlite3VdbeAddOp3(v, OP_Column, iTab, 0, iReg);
1805 }
1806 sqlite3VdbeAddOp1(v, OP_IsNull, iReg);
drha6110402005-07-28 20:51:19 +00001807 }else{
1808 pLevel->nIn = 0;
drhe23399f2005-07-22 00:31:39 +00001809 }
danielk1977b3bce662005-01-29 08:32:43 +00001810#endif
drh94a11212004-09-25 13:12:14 +00001811 }
drh0fcef5e2005-07-19 17:38:22 +00001812 disableTerm(pLevel, pTerm);
drh678ccce2008-03-31 18:19:54 +00001813 return iReg;
drh94a11212004-09-25 13:12:14 +00001814}
1815
drh51147ba2005-07-23 22:59:55 +00001816/*
1817** Generate code that will evaluate all == and IN constraints for an
1818** index. The values for all constraints are left on the stack.
1819**
1820** For example, consider table t1(a,b,c,d,e,f) with index i1(a,b,c).
1821** Suppose the WHERE clause is this: a==5 AND b IN (1,2,3) AND c>5 AND c<10
1822** The index has as many as three equality constraints, but in this
1823** example, the third "c" value is an inequality. So only two
1824** constraints are coded. This routine will generate code to evaluate
1825** a==5 and b IN (1,2,3). The current values for a and b will be left
1826** on the stack - a is the deepest and b the shallowest.
1827**
1828** In the example above nEq==2. But this subroutine works for any value
1829** of nEq including 0. If nEq==0, this routine is nearly a no-op.
1830** The only thing it does is allocate the pLevel->iMem memory cell.
1831**
1832** This routine always allocates at least one memory cell and puts
1833** the address of that memory cell in pLevel->iMem. The code that
1834** calls this routine will use pLevel->iMem to store the termination
1835** key value of the loop. If one or more IN operators appear, then
1836** this routine allocates an additional nEq memory cells for internal
1837** use.
1838*/
drh1db639c2008-01-17 02:36:28 +00001839static int codeAllEqualityTerms(
drh51147ba2005-07-23 22:59:55 +00001840 Parse *pParse, /* Parsing context */
1841 WhereLevel *pLevel, /* Which nested loop of the FROM we are coding */
1842 WhereClause *pWC, /* The WHERE clause */
drh1db639c2008-01-17 02:36:28 +00001843 Bitmask notReady, /* Which parts of FROM have not yet been coded */
1844 int nExtraReg /* Number of extra registers to allocate */
drh51147ba2005-07-23 22:59:55 +00001845){
1846 int nEq = pLevel->nEq; /* The number of == or IN constraints to code */
drh51147ba2005-07-23 22:59:55 +00001847 Vdbe *v = pParse->pVdbe; /* The virtual machine under construction */
1848 Index *pIdx = pLevel->pIdx; /* The index being used for this loop */
1849 int iCur = pLevel->iTabCur; /* The cursor of the table */
1850 WhereTerm *pTerm; /* A single constraint term */
1851 int j; /* Loop counter */
drh1db639c2008-01-17 02:36:28 +00001852 int regBase; /* Base register */
drh51147ba2005-07-23 22:59:55 +00001853
1854 /* Figure out how many memory cells we will need then allocate them.
1855 ** We always need at least one used to store the loop terminator
1856 ** value. If there are IN operators we'll need one for each == or
1857 ** IN constraint.
1858 */
drh1db639c2008-01-17 02:36:28 +00001859 pLevel->iMem = pParse->nMem + 1;
1860 regBase = pParse->nMem + 2;
1861 pParse->nMem += pLevel->nEq + 2 + nExtraReg;
drh51147ba2005-07-23 22:59:55 +00001862
1863 /* Evaluate the equality constraints
1864 */
drhc49de5d2007-01-19 01:06:01 +00001865 assert( pIdx->nColumn>=nEq );
1866 for(j=0; j<nEq; j++){
drh678ccce2008-03-31 18:19:54 +00001867 int r1;
drh51147ba2005-07-23 22:59:55 +00001868 int k = pIdx->aiColumn[j];
drhf2d315d2007-01-25 16:56:06 +00001869 pTerm = findTerm(pWC, iCur, k, notReady, pLevel->flags, pIdx);
drh51147ba2005-07-23 22:59:55 +00001870 if( pTerm==0 ) break;
1871 assert( (pTerm->flags & TERM_CODED)==0 );
drh678ccce2008-03-31 18:19:54 +00001872 r1 = codeEqualityTerm(pParse, pTerm, pLevel, regBase+j);
1873 if( r1!=regBase+j ){
1874 sqlite3VdbeAddOp2(v, OP_SCopy, r1, regBase+j);
1875 }
drh981642f2008-04-19 14:40:43 +00001876 testcase( pTerm->eOperator & WO_ISNULL );
1877 testcase( pTerm->eOperator & WO_IN );
drh72e8fa42007-03-28 14:30:06 +00001878 if( (pTerm->eOperator & (WO_ISNULL|WO_IN))==0 ){
drh1db639c2008-01-17 02:36:28 +00001879 sqlite3VdbeAddOp2(v, OP_IsNull, regBase+j, pLevel->brk);
drh51147ba2005-07-23 22:59:55 +00001880 }
1881 }
drh1db639c2008-01-17 02:36:28 +00001882 return regBase;
drh51147ba2005-07-23 22:59:55 +00001883}
1884
drh549c8b62005-09-19 13:15:23 +00001885#if defined(SQLITE_TEST)
drh84bfda42005-07-15 13:05:21 +00001886/*
1887** The following variable holds a text description of query plan generated
1888** by the most recent call to sqlite3WhereBegin(). Each call to WhereBegin
1889** overwrites the previous. This information is used for testing and
1890** analysis only.
1891*/
1892char sqlite3_query_plan[BMS*2*40]; /* Text of the join */
1893static int nQPlan = 0; /* Next free slow in _query_plan[] */
1894
1895#endif /* SQLITE_TEST */
1896
1897
drh9eff6162006-06-12 21:59:13 +00001898/*
1899** Free a WhereInfo structure
1900*/
1901static void whereInfoFree(WhereInfo *pWInfo){
1902 if( pWInfo ){
1903 int i;
1904 for(i=0; i<pWInfo->nLevel; i++){
drh4be8b512006-06-13 23:51:34 +00001905 sqlite3_index_info *pInfo = pWInfo->a[i].pIdxInfo;
1906 if( pInfo ){
drh01495b92008-01-23 12:52:40 +00001907 assert( pInfo->needToFreeIdxStr==0 );
drh17435752007-08-16 04:30:38 +00001908 sqlite3_free(pInfo);
danielk1977be8a7832006-06-13 15:00:54 +00001909 }
drh9eff6162006-06-12 21:59:13 +00001910 }
drh17435752007-08-16 04:30:38 +00001911 sqlite3_free(pWInfo);
drh9eff6162006-06-12 21:59:13 +00001912 }
1913}
1914
drh94a11212004-09-25 13:12:14 +00001915
1916/*
drhe3184742002-06-19 14:27:05 +00001917** Generate the beginning of the loop used for WHERE clause processing.
drhacf3b982005-01-03 01:27:18 +00001918** The return value is a pointer to an opaque structure that contains
drh75897232000-05-29 14:26:00 +00001919** information needed to terminate the loop. Later, the calling routine
danielk19774adee202004-05-08 08:23:19 +00001920** should invoke sqlite3WhereEnd() with the return value of this function
drh75897232000-05-29 14:26:00 +00001921** in order to complete the WHERE clause processing.
1922**
1923** If an error occurs, this routine returns NULL.
drhc27a1ce2002-06-14 20:58:45 +00001924**
1925** The basic idea is to do a nested loop, one loop for each table in
1926** the FROM clause of a select. (INSERT and UPDATE statements are the
1927** same as a SELECT with only a single table in the FROM clause.) For
1928** example, if the SQL is this:
1929**
1930** SELECT * FROM t1, t2, t3 WHERE ...;
1931**
1932** Then the code generated is conceptually like the following:
1933**
1934** foreach row1 in t1 do \ Code generated
danielk19774adee202004-05-08 08:23:19 +00001935** foreach row2 in t2 do |-- by sqlite3WhereBegin()
drhc27a1ce2002-06-14 20:58:45 +00001936** foreach row3 in t3 do /
1937** ...
1938** end \ Code generated
danielk19774adee202004-05-08 08:23:19 +00001939** end |-- by sqlite3WhereEnd()
drhc27a1ce2002-06-14 20:58:45 +00001940** end /
1941**
drh29dda4a2005-07-21 18:23:20 +00001942** Note that the loops might not be nested in the order in which they
1943** appear in the FROM clause if a different order is better able to make
drh51147ba2005-07-23 22:59:55 +00001944** use of indices. Note also that when the IN operator appears in
1945** the WHERE clause, it might result in additional nested loops for
1946** scanning through all values on the right-hand side of the IN.
drh29dda4a2005-07-21 18:23:20 +00001947**
drhc27a1ce2002-06-14 20:58:45 +00001948** There are Btree cursors associated with each table. t1 uses cursor
drh6a3ea0e2003-05-02 14:32:12 +00001949** number pTabList->a[0].iCursor. t2 uses the cursor pTabList->a[1].iCursor.
1950** And so forth. This routine generates code to open those VDBE cursors
danielk19774adee202004-05-08 08:23:19 +00001951** and sqlite3WhereEnd() generates the code to close them.
drhc27a1ce2002-06-14 20:58:45 +00001952**
drhe6f85e72004-12-25 01:03:13 +00001953** The code that sqlite3WhereBegin() generates leaves the cursors named
1954** in pTabList pointing at their appropriate entries. The [...] code
drhf0863fe2005-06-12 21:35:51 +00001955** can use OP_Column and OP_Rowid opcodes on these cursors to extract
drhe6f85e72004-12-25 01:03:13 +00001956** data from the various tables of the loop.
1957**
drhc27a1ce2002-06-14 20:58:45 +00001958** If the WHERE clause is empty, the foreach loops must each scan their
1959** entire tables. Thus a three-way join is an O(N^3) operation. But if
1960** the tables have indices and there are terms in the WHERE clause that
1961** refer to those indices, a complete table scan can be avoided and the
1962** code will run much faster. Most of the work of this routine is checking
1963** to see if there are indices that can be used to speed up the loop.
1964**
1965** Terms of the WHERE clause are also used to limit which rows actually
1966** make it to the "..." in the middle of the loop. After each "foreach",
1967** terms of the WHERE clause that use only terms in that loop and outer
1968** loops are evaluated and if false a jump is made around all subsequent
1969** inner loops (or around the "..." if the test occurs within the inner-
1970** most loop)
1971**
1972** OUTER JOINS
1973**
1974** An outer join of tables t1 and t2 is conceptally coded as follows:
1975**
1976** foreach row1 in t1 do
1977** flag = 0
1978** foreach row2 in t2 do
1979** start:
1980** ...
1981** flag = 1
1982** end
drhe3184742002-06-19 14:27:05 +00001983** if flag==0 then
1984** move the row2 cursor to a null row
1985** goto start
1986** fi
drhc27a1ce2002-06-14 20:58:45 +00001987** end
1988**
drhe3184742002-06-19 14:27:05 +00001989** ORDER BY CLAUSE PROCESSING
1990**
1991** *ppOrderBy is a pointer to the ORDER BY clause of a SELECT statement,
1992** if there is one. If there is no ORDER BY clause or if this routine
1993** is called from an UPDATE or DELETE statement, then ppOrderBy is NULL.
1994**
1995** If an index can be used so that the natural output order of the table
1996** scan is correct for the ORDER BY clause, then that index is used and
1997** *ppOrderBy is set to NULL. This is an optimization that prevents an
1998** unnecessary sort of the result set if an index appropriate for the
1999** ORDER BY clause already exists.
2000**
2001** If the where clause loops cannot be arranged to provide the correct
2002** output order, then the *ppOrderBy is unchanged.
drh75897232000-05-29 14:26:00 +00002003*/
danielk19774adee202004-05-08 08:23:19 +00002004WhereInfo *sqlite3WhereBegin(
danielk1977ed326d72004-11-16 15:50:19 +00002005 Parse *pParse, /* The parser context */
2006 SrcList *pTabList, /* A list of all tables to be scanned */
2007 Expr *pWhere, /* The WHERE clause */
danielk1977a9d1ccb2008-01-05 17:39:29 +00002008 ExprList **ppOrderBy, /* An ORDER BY clause, or NULL */
drh08c88eb2008-04-10 13:33:18 +00002009 u8 wflags /* One of the WHERE_* flags defined in sqliteInt.h */
drh75897232000-05-29 14:26:00 +00002010){
2011 int i; /* Loop counter */
2012 WhereInfo *pWInfo; /* Will become the return value of this function */
2013 Vdbe *v = pParse->pVdbe; /* The virtual database engine */
drhd4f5ee22003-07-16 00:54:31 +00002014 int brk, cont = 0; /* Addresses used during code generation */
drhfe05af82005-07-21 03:14:59 +00002015 Bitmask notReady; /* Cursors that are not yet positioned */
drh0aa74ed2005-07-16 13:33:20 +00002016 WhereTerm *pTerm; /* A single term in the WHERE clause */
2017 ExprMaskSet maskSet; /* The expression mask set */
drh0aa74ed2005-07-16 13:33:20 +00002018 WhereClause wc; /* The WHERE clause is divided into these terms */
drh9012bcb2004-12-19 00:11:35 +00002019 struct SrcList_item *pTabItem; /* A single entry from pTabList */
2020 WhereLevel *pLevel; /* A single level in the pWInfo list */
drh29dda4a2005-07-21 18:23:20 +00002021 int iFrom; /* First unused FROM clause element */
drh943af3c2005-07-29 19:43:58 +00002022 int andFlags; /* AND-ed combination of all wc.a[].flags */
drh17435752007-08-16 04:30:38 +00002023 sqlite3 *db; /* Database connection */
danielk1977a9d1ccb2008-01-05 17:39:29 +00002024 ExprList *pOrderBy = 0;
drh75897232000-05-29 14:26:00 +00002025
drh29dda4a2005-07-21 18:23:20 +00002026 /* The number of tables in the FROM clause is limited by the number of
drh1398ad32005-01-19 23:24:50 +00002027 ** bits in a Bitmask
2028 */
drh29dda4a2005-07-21 18:23:20 +00002029 if( pTabList->nSrc>BMS ){
2030 sqlite3ErrorMsg(pParse, "at most %d tables in a join", BMS);
drh1398ad32005-01-19 23:24:50 +00002031 return 0;
2032 }
2033
danielk1977a9d1ccb2008-01-05 17:39:29 +00002034 if( ppOrderBy ){
2035 pOrderBy = *ppOrderBy;
2036 }
2037
drh83dcb1a2002-06-28 01:02:38 +00002038 /* Split the WHERE clause into separate subexpressions where each
drh29dda4a2005-07-21 18:23:20 +00002039 ** subexpression is separated by an AND operator.
drh83dcb1a2002-06-28 01:02:38 +00002040 */
drh6a3ea0e2003-05-02 14:32:12 +00002041 initMaskSet(&maskSet);
drh7b4fc6a2007-02-06 13:26:32 +00002042 whereClauseInit(&wc, pParse, &maskSet);
drh678ccce2008-03-31 18:19:54 +00002043 sqlite3ExprCodeConstants(pParse, pWhere);
drh6c30be82005-07-29 15:10:17 +00002044 whereSplit(&wc, pWhere, TK_AND);
drh1398ad32005-01-19 23:24:50 +00002045
drh75897232000-05-29 14:26:00 +00002046 /* Allocate and initialize the WhereInfo structure that will become the
2047 ** return value.
2048 */
drh17435752007-08-16 04:30:38 +00002049 db = pParse->db;
2050 pWInfo = sqlite3DbMallocZero(db,
2051 sizeof(WhereInfo) + pTabList->nSrc*sizeof(WhereLevel));
2052 if( db->mallocFailed ){
drhe23399f2005-07-22 00:31:39 +00002053 goto whereBeginNoMem;
drh75897232000-05-29 14:26:00 +00002054 }
danielk197770b6d572006-06-19 04:49:34 +00002055 pWInfo->nLevel = pTabList->nSrc;
drh75897232000-05-29 14:26:00 +00002056 pWInfo->pParse = pParse;
2057 pWInfo->pTabList = pTabList;
danielk19774adee202004-05-08 08:23:19 +00002058 pWInfo->iBreak = sqlite3VdbeMakeLabel(v);
drh08192d52002-04-30 19:20:28 +00002059
2060 /* Special case: a WHERE clause that is constant. Evaluate the
2061 ** expression and either jump over all of the code or fall thru.
2062 */
drh0a168372007-06-08 00:20:47 +00002063 if( pWhere && (pTabList->nSrc==0 || sqlite3ExprIsConstantNotJoin(pWhere)) ){
drh35573352008-01-08 23:54:25 +00002064 sqlite3ExprIfFalse(pParse, pWhere, pWInfo->iBreak, SQLITE_JUMPIFNULL);
drhdf199a22002-06-14 22:38:41 +00002065 pWhere = 0;
drh08192d52002-04-30 19:20:28 +00002066 }
drh75897232000-05-29 14:26:00 +00002067
drh42165be2008-03-26 14:56:34 +00002068 /* Assign a bit from the bitmask to every term in the FROM clause.
2069 **
2070 ** When assigning bitmask values to FROM clause cursors, it must be
2071 ** the case that if X is the bitmask for the N-th FROM clause term then
2072 ** the bitmask for all FROM clause terms to the left of the N-th term
2073 ** is (X-1). An expression from the ON clause of a LEFT JOIN can use
2074 ** its Expr.iRightJoinTable value to find the bitmask of the right table
2075 ** of the join. Subtracting one from the right table bitmask gives a
2076 ** bitmask for all tables to the left of the join. Knowing the bitmask
2077 ** for all tables to the left of a left join is important. Ticket #3015.
2078 */
2079 for(i=0; i<pTabList->nSrc; i++){
2080 createMask(&maskSet, pTabList->a[i].iCursor);
2081 }
2082#ifndef NDEBUG
2083 {
2084 Bitmask toTheLeft = 0;
2085 for(i=0; i<pTabList->nSrc; i++){
2086 Bitmask m = getMask(&maskSet, pTabList->a[i].iCursor);
2087 assert( (m-1)==toTheLeft );
2088 toTheLeft |= m;
2089 }
2090 }
2091#endif
2092
drh29dda4a2005-07-21 18:23:20 +00002093 /* Analyze all of the subexpressions. Note that exprAnalyze() might
2094 ** add new virtual terms onto the end of the WHERE clause. We do not
2095 ** want to analyze these virtual terms, so start analyzing at the end
drhb6fb62d2005-09-20 08:47:20 +00002096 ** and work forward so that the added virtual terms are never processed.
drh75897232000-05-29 14:26:00 +00002097 */
drh7b4fc6a2007-02-06 13:26:32 +00002098 exprAnalyzeAll(pTabList, &wc);
drh17435752007-08-16 04:30:38 +00002099 if( db->mallocFailed ){
drh0bbaa1b2005-08-19 19:14:12 +00002100 goto whereBeginNoMem;
2101 }
drh75897232000-05-29 14:26:00 +00002102
drh29dda4a2005-07-21 18:23:20 +00002103 /* Chose the best index to use for each table in the FROM clause.
2104 **
drh51147ba2005-07-23 22:59:55 +00002105 ** This loop fills in the following fields:
2106 **
2107 ** pWInfo->a[].pIdx The index to use for this level of the loop.
2108 ** pWInfo->a[].flags WHERE_xxx flags associated with pIdx
2109 ** pWInfo->a[].nEq The number of == and IN constraints
2110 ** pWInfo->a[].iFrom When term of the FROM clause is being coded
2111 ** pWInfo->a[].iTabCur The VDBE cursor for the database table
2112 ** pWInfo->a[].iIdxCur The VDBE cursor for the index
2113 **
2114 ** This loop also figures out the nesting order of tables in the FROM
2115 ** clause.
drh75897232000-05-29 14:26:00 +00002116 */
drhfe05af82005-07-21 03:14:59 +00002117 notReady = ~(Bitmask)0;
drh9012bcb2004-12-19 00:11:35 +00002118 pTabItem = pTabList->a;
2119 pLevel = pWInfo->a;
drh943af3c2005-07-29 19:43:58 +00002120 andFlags = ~0;
drh4f0c5872007-03-26 22:05:01 +00002121 WHERETRACE(("*** Optimizer Start ***\n"));
drh29dda4a2005-07-21 18:23:20 +00002122 for(i=iFrom=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){
2123 Index *pIdx; /* Index for FROM table at pTabItem */
2124 int flags; /* Flags asssociated with pIdx */
drh51147ba2005-07-23 22:59:55 +00002125 int nEq; /* Number of == or IN constraints */
2126 double cost; /* The cost for pIdx */
drh29dda4a2005-07-21 18:23:20 +00002127 int j; /* For looping over FROM tables */
2128 Index *pBest = 0; /* The best index seen so far */
2129 int bestFlags = 0; /* Flags associated with pBest */
drh51147ba2005-07-23 22:59:55 +00002130 int bestNEq = 0; /* nEq associated with pBest */
drhb37df7b2005-10-13 02:09:49 +00002131 double lowestCost; /* Cost of the pBest */
drh02afc862006-01-20 18:10:57 +00002132 int bestJ = 0; /* The value of j */
drh29dda4a2005-07-21 18:23:20 +00002133 Bitmask m; /* Bitmask value for j or bestJ */
drh570b9352006-02-01 02:45:02 +00002134 int once = 0; /* True when first table is seen */
drh6d209d82006-06-27 01:54:26 +00002135 sqlite3_index_info *pIndex; /* Current virtual index */
drh29dda4a2005-07-21 18:23:20 +00002136
drhb37df7b2005-10-13 02:09:49 +00002137 lowestCost = SQLITE_BIG_DBL;
drh29dda4a2005-07-21 18:23:20 +00002138 for(j=iFrom, pTabItem=&pTabList->a[j]; j<pTabList->nSrc; j++, pTabItem++){
drhdf26fd52006-06-06 11:45:54 +00002139 int doNotReorder; /* True if this table should not be reordered */
2140
drh61dfc312006-12-16 16:25:15 +00002141 doNotReorder = (pTabItem->jointype & (JT_LEFT|JT_CROSS))!=0;
drhdf26fd52006-06-06 11:45:54 +00002142 if( once && doNotReorder ) break;
drh29dda4a2005-07-21 18:23:20 +00002143 m = getMask(&maskSet, pTabItem->iCursor);
2144 if( (m & notReady)==0 ){
2145 if( j==iFrom ) iFrom++;
2146 continue;
2147 }
drh9eff6162006-06-12 21:59:13 +00002148 assert( pTabItem->pTab );
2149#ifndef SQLITE_OMIT_VIRTUALTABLE
drh4cbdda92006-06-14 19:00:20 +00002150 if( IsVirtual(pTabItem->pTab) ){
drh6d209d82006-06-27 01:54:26 +00002151 sqlite3_index_info **ppIdxInfo = &pWInfo->a[j].pIdxInfo;
drh9eff6162006-06-12 21:59:13 +00002152 cost = bestVirtualIndex(pParse, &wc, pTabItem, notReady,
2153 ppOrderBy ? *ppOrderBy : 0, i==0,
drh6d209d82006-06-27 01:54:26 +00002154 ppIdxInfo);
drh9eff6162006-06-12 21:59:13 +00002155 flags = WHERE_VIRTUALTABLE;
drh6d209d82006-06-27 01:54:26 +00002156 pIndex = *ppIdxInfo;
danielk197793626f42006-06-20 13:07:27 +00002157 if( pIndex && pIndex->orderByConsumed ){
drh1a90e092006-06-14 22:07:10 +00002158 flags = WHERE_VIRTUALTABLE | WHERE_ORDERBY;
2159 }
drh9eff6162006-06-12 21:59:13 +00002160 pIdx = 0;
2161 nEq = 0;
danielk19778efe5412007-03-02 08:12:22 +00002162 if( (SQLITE_BIG_DBL/2.0)<cost ){
2163 /* The cost is not allowed to be larger than SQLITE_BIG_DBL (the
2164 ** inital value of lowestCost in this loop. If it is, then
2165 ** the (cost<lowestCost) test below will never be true and
2166 ** pLevel->pBestIdx never set.
2167 */
2168 cost = (SQLITE_BIG_DBL/2.0);
2169 }
drh9eff6162006-06-12 21:59:13 +00002170 }else
2171#endif
2172 {
2173 cost = bestIndex(pParse, &wc, pTabItem, notReady,
2174 (i==0 && ppOrderBy) ? *ppOrderBy : 0,
2175 &pIdx, &flags, &nEq);
drh9861a9f2006-06-27 02:33:40 +00002176 pIndex = 0;
drh9eff6162006-06-12 21:59:13 +00002177 }
drh51147ba2005-07-23 22:59:55 +00002178 if( cost<lowestCost ){
drh570b9352006-02-01 02:45:02 +00002179 once = 1;
drh51147ba2005-07-23 22:59:55 +00002180 lowestCost = cost;
drh29dda4a2005-07-21 18:23:20 +00002181 pBest = pIdx;
2182 bestFlags = flags;
drh51147ba2005-07-23 22:59:55 +00002183 bestNEq = nEq;
drh29dda4a2005-07-21 18:23:20 +00002184 bestJ = j;
drh6d209d82006-06-27 01:54:26 +00002185 pLevel->pBestIdx = pIndex;
drh29dda4a2005-07-21 18:23:20 +00002186 }
drhdf26fd52006-06-06 11:45:54 +00002187 if( doNotReorder ) break;
drh29dda4a2005-07-21 18:23:20 +00002188 }
drh4f0c5872007-03-26 22:05:01 +00002189 WHERETRACE(("*** Optimizer choose table %d for loop %d\n", bestJ,
drh3dec2232005-09-10 15:28:09 +00002190 pLevel-pWInfo->a));
drh943af3c2005-07-29 19:43:58 +00002191 if( (bestFlags & WHERE_ORDERBY)!=0 ){
drhfe05af82005-07-21 03:14:59 +00002192 *ppOrderBy = 0;
drhc4a3c772001-04-04 11:48:57 +00002193 }
drh943af3c2005-07-29 19:43:58 +00002194 andFlags &= bestFlags;
drh29dda4a2005-07-21 18:23:20 +00002195 pLevel->flags = bestFlags;
drhfe05af82005-07-21 03:14:59 +00002196 pLevel->pIdx = pBest;
drh51147ba2005-07-23 22:59:55 +00002197 pLevel->nEq = bestNEq;
drhe23399f2005-07-22 00:31:39 +00002198 pLevel->aInLoop = 0;
2199 pLevel->nIn = 0;
drhfe05af82005-07-21 03:14:59 +00002200 if( pBest ){
drh9012bcb2004-12-19 00:11:35 +00002201 pLevel->iIdxCur = pParse->nTab++;
drhfe05af82005-07-21 03:14:59 +00002202 }else{
2203 pLevel->iIdxCur = -1;
drh6b563442001-11-07 16:48:26 +00002204 }
drh29dda4a2005-07-21 18:23:20 +00002205 notReady &= ~getMask(&maskSet, pTabList->a[bestJ].iCursor);
2206 pLevel->iFrom = bestJ;
drh75897232000-05-29 14:26:00 +00002207 }
drh4f0c5872007-03-26 22:05:01 +00002208 WHERETRACE(("*** Optimizer Finished ***\n"));
drh75897232000-05-29 14:26:00 +00002209
drh943af3c2005-07-29 19:43:58 +00002210 /* If the total query only selects a single row, then the ORDER BY
2211 ** clause is irrelevant.
2212 */
2213 if( (andFlags & WHERE_UNIQUE)!=0 && ppOrderBy ){
2214 *ppOrderBy = 0;
2215 }
2216
drh08c88eb2008-04-10 13:33:18 +00002217 /* If the caller is an UPDATE or DELETE statement that is requesting
2218 ** to use a one-pass algorithm, determine if this is appropriate.
2219 ** The one-pass algorithm only works if the WHERE clause constraints
2220 ** the statement to update a single row.
2221 */
2222 assert( (wflags & WHERE_ONEPASS_DESIRED)==0 || pWInfo->nLevel==1 );
2223 if( (wflags & WHERE_ONEPASS_DESIRED)!=0 && (andFlags & WHERE_UNIQUE)!=0 ){
2224 pWInfo->okOnePass = 1;
2225 pWInfo->a[0].flags &= ~WHERE_IDX_ONLY;
2226 }
2227
drh9012bcb2004-12-19 00:11:35 +00002228 /* Open all tables in the pTabList and any indices selected for
2229 ** searching those tables.
2230 */
2231 sqlite3CodeVerifySchema(pParse, -1); /* Insert the cookie verifier Goto */
drh29dda4a2005-07-21 18:23:20 +00002232 for(i=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){
danielk1977da184232006-01-05 11:34:32 +00002233 Table *pTab; /* Table to open */
2234 Index *pIx; /* Index used to access pTab (if any) */
2235 int iDb; /* Index of database containing table/index */
drh9012bcb2004-12-19 00:11:35 +00002236 int iIdxCur = pLevel->iIdxCur;
2237
drhecc92422005-09-10 16:46:12 +00002238#ifndef SQLITE_OMIT_EXPLAIN
2239 if( pParse->explain==2 ){
2240 char *zMsg;
2241 struct SrcList_item *pItem = &pTabList->a[pLevel->iFrom];
danielk19771e536952007-08-16 10:09:01 +00002242 zMsg = sqlite3MPrintf(db, "TABLE %s", pItem->zName);
drhecc92422005-09-10 16:46:12 +00002243 if( pItem->zAlias ){
danielk19771e536952007-08-16 10:09:01 +00002244 zMsg = sqlite3MPrintf(db, "%z AS %s", zMsg, pItem->zAlias);
drhecc92422005-09-10 16:46:12 +00002245 }
2246 if( (pIx = pLevel->pIdx)!=0 ){
danielk19771e536952007-08-16 10:09:01 +00002247 zMsg = sqlite3MPrintf(db, "%z WITH INDEX %s", zMsg, pIx->zName);
drh36d64932005-11-21 12:46:27 +00002248 }else if( pLevel->flags & (WHERE_ROWID_EQ|WHERE_ROWID_RANGE) ){
danielk19771e536952007-08-16 10:09:01 +00002249 zMsg = sqlite3MPrintf(db, "%z USING PRIMARY KEY", zMsg);
drhecc92422005-09-10 16:46:12 +00002250 }
drh9eff6162006-06-12 21:59:13 +00002251#ifndef SQLITE_OMIT_VIRTUALTABLE
drh6d209d82006-06-27 01:54:26 +00002252 else if( pLevel->pBestIdx ){
2253 sqlite3_index_info *pBestIdx = pLevel->pBestIdx;
danielk19771e536952007-08-16 10:09:01 +00002254 zMsg = sqlite3MPrintf(db, "%z VIRTUAL TABLE INDEX %d:%s", zMsg,
drh6d209d82006-06-27 01:54:26 +00002255 pBestIdx->idxNum, pBestIdx->idxStr);
drh9eff6162006-06-12 21:59:13 +00002256 }
2257#endif
drhe2b39092006-04-21 09:38:36 +00002258 if( pLevel->flags & WHERE_ORDERBY ){
danielk19771e536952007-08-16 10:09:01 +00002259 zMsg = sqlite3MPrintf(db, "%z ORDER BY", zMsg);
drhe2b39092006-04-21 09:38:36 +00002260 }
drh66a51672008-01-03 00:01:23 +00002261 sqlite3VdbeAddOp4(v, OP_Explain, i, pLevel->iFrom, 0, zMsg, P4_DYNAMIC);
drhecc92422005-09-10 16:46:12 +00002262 }
2263#endif /* SQLITE_OMIT_EXPLAIN */
drh29dda4a2005-07-21 18:23:20 +00002264 pTabItem = &pTabList->a[pLevel->iFrom];
drh9012bcb2004-12-19 00:11:35 +00002265 pTab = pTabItem->pTab;
danielk1977da184232006-01-05 11:34:32 +00002266 iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
drhb9bb7c12006-06-11 23:41:55 +00002267 if( pTab->isEphem || pTab->pSelect ) continue;
drh9eff6162006-06-12 21:59:13 +00002268#ifndef SQLITE_OMIT_VIRTUALTABLE
drh6d209d82006-06-27 01:54:26 +00002269 if( pLevel->pBestIdx ){
danielk197793626f42006-06-20 13:07:27 +00002270 int iCur = pTabItem->iCursor;
drh66a51672008-01-03 00:01:23 +00002271 sqlite3VdbeAddOp4(v, OP_VOpen, iCur, 0, 0,
2272 (const char*)pTab->pVtab, P4_VTAB);
drh9eff6162006-06-12 21:59:13 +00002273 }else
2274#endif
drhfe05af82005-07-21 03:14:59 +00002275 if( (pLevel->flags & WHERE_IDX_ONLY)==0 ){
drh08c88eb2008-04-10 13:33:18 +00002276 int op = pWInfo->okOnePass ? OP_OpenWrite : OP_OpenRead;
2277 sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, op);
2278 if( !pWInfo->okOnePass && pTab->nCol<(sizeof(Bitmask)*8) ){
danielk19779792eef2006-01-13 15:58:43 +00002279 Bitmask b = pTabItem->colUsed;
2280 int n = 0;
drh74161702006-02-24 02:53:49 +00002281 for(; b; b=b>>1, n++){}
danielk1977cd3e8f72008-03-25 09:47:35 +00002282 sqlite3VdbeChangeP2(v, sqlite3VdbeCurrentAddr(v)-2, n);
danielk19779792eef2006-01-13 15:58:43 +00002283 assert( n<=pTab->nCol );
2284 }
danielk1977c00da102006-01-07 13:21:04 +00002285 }else{
2286 sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
drh9012bcb2004-12-19 00:11:35 +00002287 }
2288 pLevel->iTabCur = pTabItem->iCursor;
2289 if( (pIx = pLevel->pIdx)!=0 ){
danielk1977b3bf5562006-01-10 17:58:23 +00002290 KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIx);
danielk1977da184232006-01-05 11:34:32 +00002291 assert( pIx->pSchema==pTab->pSchema );
danielk1977cd3e8f72008-03-25 09:47:35 +00002292 sqlite3VdbeAddOp2(v, OP_SetNumColumns, 0, pIx->nColumn+1);
danielk1977207872a2008-01-03 07:54:23 +00002293 sqlite3VdbeAddOp4(v, OP_OpenRead, iIdxCur, pIx->tnum, iDb,
drh66a51672008-01-03 00:01:23 +00002294 (char*)pKey, P4_KEYINFO_HANDOFF);
danielk1977207872a2008-01-03 07:54:23 +00002295 VdbeComment((v, "%s", pIx->zName));
drh9012bcb2004-12-19 00:11:35 +00002296 }
danielk1977da184232006-01-05 11:34:32 +00002297 sqlite3CodeVerifySchema(pParse, iDb);
drh9012bcb2004-12-19 00:11:35 +00002298 }
2299 pWInfo->iTop = sqlite3VdbeCurrentAddr(v);
2300
drh29dda4a2005-07-21 18:23:20 +00002301 /* Generate the code to do the search. Each iteration of the for
2302 ** loop below generates code for a single nested loop of the VM
2303 ** program.
drh75897232000-05-29 14:26:00 +00002304 */
drhfe05af82005-07-21 03:14:59 +00002305 notReady = ~(Bitmask)0;
drh29dda4a2005-07-21 18:23:20 +00002306 for(i=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){
drhfe05af82005-07-21 03:14:59 +00002307 int j;
drh9012bcb2004-12-19 00:11:35 +00002308 int iCur = pTabItem->iCursor; /* The VDBE cursor for the table */
2309 Index *pIdx; /* The index we will be using */
drh72e8fa42007-03-28 14:30:06 +00002310 int nxt; /* Where to jump to continue with the next IN case */
drh9012bcb2004-12-19 00:11:35 +00002311 int iIdxCur; /* The VDBE cursor for the index */
2312 int omitTable; /* True if we use the index only */
drh29dda4a2005-07-21 18:23:20 +00002313 int bRev; /* True if we need to scan in reverse order */
drh9012bcb2004-12-19 00:11:35 +00002314
drh29dda4a2005-07-21 18:23:20 +00002315 pTabItem = &pTabList->a[pLevel->iFrom];
2316 iCur = pTabItem->iCursor;
drh9012bcb2004-12-19 00:11:35 +00002317 pIdx = pLevel->pIdx;
2318 iIdxCur = pLevel->iIdxCur;
drh29dda4a2005-07-21 18:23:20 +00002319 bRev = (pLevel->flags & WHERE_REVERSE)!=0;
drhfe05af82005-07-21 03:14:59 +00002320 omitTable = (pLevel->flags & WHERE_IDX_ONLY)!=0;
drh75897232000-05-29 14:26:00 +00002321
drh29dda4a2005-07-21 18:23:20 +00002322 /* Create labels for the "break" and "continue" instructions
2323 ** for the current loop. Jump to brk to break out of a loop.
2324 ** Jump to cont to go immediately to the next iteration of the
2325 ** loop.
drh72e8fa42007-03-28 14:30:06 +00002326 **
2327 ** When there is an IN operator, we also have a "nxt" label that
2328 ** means to continue with the next IN value combination. When
2329 ** there are no IN operators in the constraints, the "nxt" label
2330 ** is the same as "brk".
drh29dda4a2005-07-21 18:23:20 +00002331 */
drh72e8fa42007-03-28 14:30:06 +00002332 brk = pLevel->brk = pLevel->nxt = sqlite3VdbeMakeLabel(v);
drh29dda4a2005-07-21 18:23:20 +00002333 cont = pLevel->cont = sqlite3VdbeMakeLabel(v);
2334
drhad2d8302002-05-24 20:31:36 +00002335 /* If this is the right table of a LEFT OUTER JOIN, allocate and
drh174b6192002-12-03 02:22:52 +00002336 ** initialize a memory cell that records if this table matches any
drhc27a1ce2002-06-14 20:58:45 +00002337 ** row of the left table of the join.
drhad2d8302002-05-24 20:31:36 +00002338 */
drh61dfc312006-12-16 16:25:15 +00002339 if( pLevel->iFrom>0 && (pTabItem[0].jointype & JT_LEFT)!=0 ){
drh0a07c102008-01-03 18:03:08 +00002340 pLevel->iLeftJoin = ++pParse->nMem;
drh4c583122008-01-04 22:01:03 +00002341 sqlite3VdbeAddOp2(v, OP_Integer, 0, pLevel->iLeftJoin);
drhd4e70eb2008-01-02 00:34:36 +00002342 VdbeComment((v, "init LEFT JOIN no-match flag"));
drhad2d8302002-05-24 20:31:36 +00002343 }
2344
drh9eff6162006-06-12 21:59:13 +00002345#ifndef SQLITE_OMIT_VIRTUALTABLE
drh6d209d82006-06-27 01:54:26 +00002346 if( pLevel->pBestIdx ){
drh7f375902006-06-13 17:38:59 +00002347 /* Case 0: The table is a virtual-table. Use the VFilter and VNext
2348 ** to access the data.
2349 */
drh9861a9f2006-06-27 02:33:40 +00002350 int j;
danielk19776dbee812008-01-03 18:39:41 +00002351 int iReg; /* P3 Value for OP_VFilter */
drh6d209d82006-06-27 01:54:26 +00002352 sqlite3_index_info *pBestIdx = pLevel->pBestIdx;
2353 int nConstraint = pBestIdx->nConstraint;
drh4be8b512006-06-13 23:51:34 +00002354 struct sqlite3_index_constraint_usage *aUsage =
drh6d209d82006-06-27 01:54:26 +00002355 pBestIdx->aConstraintUsage;
drh4be8b512006-06-13 23:51:34 +00002356 const struct sqlite3_index_constraint *aConstraint =
drh6d209d82006-06-27 01:54:26 +00002357 pBestIdx->aConstraint;
drh4be8b512006-06-13 23:51:34 +00002358
drh1db639c2008-01-17 02:36:28 +00002359 iReg = sqlite3GetTempRange(pParse, nConstraint+2);
danielk19772d1a8d22008-05-16 15:40:40 +00002360 pParse->disableColCache++;
drh9861a9f2006-06-27 02:33:40 +00002361 for(j=1; j<=nConstraint; j++){
2362 int k;
2363 for(k=0; k<nConstraint; k++){
2364 if( aUsage[k].argvIndex==j ){
danielk19773851a652006-06-27 12:16:56 +00002365 int iTerm = aConstraint[k].iTermOffset;
drh1db639c2008-01-17 02:36:28 +00002366 sqlite3ExprCode(pParse, wc.a[iTerm].pExpr->pRight, iReg+j+1);
drh9eff6162006-06-12 21:59:13 +00002367 break;
2368 }
2369 }
drh9861a9f2006-06-27 02:33:40 +00002370 if( k==nConstraint ) break;
drh9eff6162006-06-12 21:59:13 +00002371 }
danielk19772d1a8d22008-05-16 15:40:40 +00002372 pParse->disableColCache--;
drh4c583122008-01-04 22:01:03 +00002373 sqlite3VdbeAddOp2(v, OP_Integer, pBestIdx->idxNum, iReg);
2374 sqlite3VdbeAddOp2(v, OP_Integer, j-1, iReg+1);
danielk19776dbee812008-01-03 18:39:41 +00002375 sqlite3VdbeAddOp4(v, OP_VFilter, iCur, brk, iReg, pBestIdx->idxStr,
drh66a51672008-01-03 00:01:23 +00002376 pBestIdx->needToFreeIdxStr ? P4_MPRINTF : P4_STATIC);
drh1db639c2008-01-17 02:36:28 +00002377 sqlite3ReleaseTempRange(pParse, iReg, nConstraint+2);
drh6d209d82006-06-27 01:54:26 +00002378 pBestIdx->needToFreeIdxStr = 0;
drh9861a9f2006-06-27 02:33:40 +00002379 for(j=0; j<pBestIdx->nConstraint; j++){
2380 if( aUsage[j].omit ){
2381 int iTerm = aConstraint[j].iTermOffset;
2382 disableTerm(pLevel, &wc.a[iTerm]);
drh9eff6162006-06-12 21:59:13 +00002383 }
2384 }
2385 pLevel->op = OP_VNext;
drha967e882006-06-13 01:04:52 +00002386 pLevel->p1 = iCur;
2387 pLevel->p2 = sqlite3VdbeCurrentAddr(v);
drh9eff6162006-06-12 21:59:13 +00002388 }else
2389#endif /* SQLITE_OMIT_VIRTUALTABLE */
2390
drhfe05af82005-07-21 03:14:59 +00002391 if( pLevel->flags & WHERE_ROWID_EQ ){
drh8aff1012001-12-22 14:49:24 +00002392 /* Case 1: We can directly reference a single row using an
drhc27a1ce2002-06-14 20:58:45 +00002393 ** equality comparison against the ROWID field. Or
2394 ** we reference multiple rows using a "rowid IN (...)"
2395 ** construct.
drhc4a3c772001-04-04 11:48:57 +00002396 */
drh1db639c2008-01-17 02:36:28 +00002397 int r1;
drhfe05af82005-07-21 03:14:59 +00002398 pTerm = findTerm(&wc, iCur, -1, notReady, WO_EQ|WO_IN, 0);
2399 assert( pTerm!=0 );
drh0fcef5e2005-07-19 17:38:22 +00002400 assert( pTerm->pExpr!=0 );
2401 assert( pTerm->leftCursor==iCur );
drh9012bcb2004-12-19 00:11:35 +00002402 assert( omitTable==0 );
drh678ccce2008-03-31 18:19:54 +00002403 r1 = codeEqualityTerm(pParse, pTerm, pLevel, 0);
drh72e8fa42007-03-28 14:30:06 +00002404 nxt = pLevel->nxt;
drh678ccce2008-03-31 18:19:54 +00002405 sqlite3VdbeAddOp2(v, OP_MustBeInt, r1, nxt);
drh1db639c2008-01-17 02:36:28 +00002406 sqlite3VdbeAddOp3(v, OP_NotExists, iCur, nxt, r1);
tpoindex7a9b1612005-01-03 18:13:18 +00002407 VdbeComment((v, "pk"));
drh6b563442001-11-07 16:48:26 +00002408 pLevel->op = OP_Noop;
drhfe05af82005-07-21 03:14:59 +00002409 }else if( pLevel->flags & WHERE_ROWID_RANGE ){
drh51147ba2005-07-23 22:59:55 +00002410 /* Case 2: We have an inequality comparison against the ROWID field.
drh8aff1012001-12-22 14:49:24 +00002411 */
2412 int testOp = OP_Noop;
2413 int start;
drhfe05af82005-07-21 03:14:59 +00002414 WhereTerm *pStart, *pEnd;
drh8aff1012001-12-22 14:49:24 +00002415
drh9012bcb2004-12-19 00:11:35 +00002416 assert( omitTable==0 );
drha6110402005-07-28 20:51:19 +00002417 pStart = findTerm(&wc, iCur, -1, notReady, WO_GT|WO_GE, 0);
2418 pEnd = findTerm(&wc, iCur, -1, notReady, WO_LT|WO_LE, 0);
drhfe05af82005-07-21 03:14:59 +00002419 if( bRev ){
2420 pTerm = pStart;
2421 pStart = pEnd;
2422 pEnd = pTerm;
2423 }
2424 if( pStart ){
drh94a11212004-09-25 13:12:14 +00002425 Expr *pX;
drh1db639c2008-01-17 02:36:28 +00002426 int r1, regFree1;
drhfe05af82005-07-21 03:14:59 +00002427 pX = pStart->pExpr;
drh94a11212004-09-25 13:12:14 +00002428 assert( pX!=0 );
drhfe05af82005-07-21 03:14:59 +00002429 assert( pStart->leftCursor==iCur );
drh1db639c2008-01-17 02:36:28 +00002430 r1 = sqlite3ExprCodeTemp(pParse, pX->pRight, &regFree1);
2431 sqlite3VdbeAddOp3(v, OP_ForceInt, r1, brk,
drh41c2bf02008-01-05 05:38:21 +00002432 pX->op==TK_LE || pX->op==TK_GT);
drh1db639c2008-01-17 02:36:28 +00002433 sqlite3VdbeAddOp3(v, bRev ? OP_MoveLt : OP_MoveGe, iCur, brk, r1);
tpoindex7a9b1612005-01-03 18:13:18 +00002434 VdbeComment((v, "pk"));
drh1db639c2008-01-17 02:36:28 +00002435 sqlite3ReleaseTempReg(pParse, regFree1);
drhfe05af82005-07-21 03:14:59 +00002436 disableTerm(pLevel, pStart);
drh8aff1012001-12-22 14:49:24 +00002437 }else{
drh66a51672008-01-03 00:01:23 +00002438 sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iCur, brk);
drh8aff1012001-12-22 14:49:24 +00002439 }
drhfe05af82005-07-21 03:14:59 +00002440 if( pEnd ){
drh94a11212004-09-25 13:12:14 +00002441 Expr *pX;
drhfe05af82005-07-21 03:14:59 +00002442 pX = pEnd->pExpr;
drh94a11212004-09-25 13:12:14 +00002443 assert( pX!=0 );
drhfe05af82005-07-21 03:14:59 +00002444 assert( pEnd->leftCursor==iCur );
drh0a07c102008-01-03 18:03:08 +00002445 pLevel->iMem = ++pParse->nMem;
drh1db639c2008-01-17 02:36:28 +00002446 sqlite3ExprCode(pParse, pX->pRight, pLevel->iMem);
drh94a11212004-09-25 13:12:14 +00002447 if( pX->op==TK_LT || pX->op==TK_GT ){
drhb6c29892004-11-22 19:12:19 +00002448 testOp = bRev ? OP_Le : OP_Ge;
drh8aff1012001-12-22 14:49:24 +00002449 }else{
drhb6c29892004-11-22 19:12:19 +00002450 testOp = bRev ? OP_Lt : OP_Gt;
drh8aff1012001-12-22 14:49:24 +00002451 }
drhfe05af82005-07-21 03:14:59 +00002452 disableTerm(pLevel, pEnd);
drh8aff1012001-12-22 14:49:24 +00002453 }
danielk19774adee202004-05-08 08:23:19 +00002454 start = sqlite3VdbeCurrentAddr(v);
drhb6c29892004-11-22 19:12:19 +00002455 pLevel->op = bRev ? OP_Prev : OP_Next;
drh6a3ea0e2003-05-02 14:32:12 +00002456 pLevel->p1 = iCur;
drh8aff1012001-12-22 14:49:24 +00002457 pLevel->p2 = start;
2458 if( testOp!=OP_Noop ){
drh1db639c2008-01-17 02:36:28 +00002459 int r1 = sqlite3GetTempReg(pParse);
2460 sqlite3VdbeAddOp2(v, OP_Rowid, iCur, r1);
2461 /* sqlite3VdbeAddOp2(v, OP_SCopy, pLevel->iMem, 0); */
2462 sqlite3VdbeAddOp3(v, testOp, pLevel->iMem, brk, r1);
drh35573352008-01-08 23:54:25 +00002463 sqlite3VdbeChangeP5(v, SQLITE_AFF_NUMERIC | SQLITE_JUMPIFNULL);
drh1db639c2008-01-17 02:36:28 +00002464 sqlite3ReleaseTempReg(pParse, r1);
drh8aff1012001-12-22 14:49:24 +00002465 }
danielk1977b790c6c2008-04-18 10:25:24 +00002466 }else if( pLevel->flags & (WHERE_COLUMN_RANGE|WHERE_COLUMN_EQ) ){
2467 /* Case 3: A scan using an index.
2468 **
drh981642f2008-04-19 14:40:43 +00002469 ** The WHERE clause may contain zero or more equality
danielk1977b790c6c2008-04-18 10:25:24 +00002470 ** terms ("==" or "IN" operators) that refer to the N
2471 ** left-most columns of the index. It may also contain
2472 ** inequality constraints (>, <, >= or <=) on the indexed
2473 ** column that immediately follows the N equalities. Only
2474 ** the right-most column can be an inequality - the rest must
2475 ** use the "==" and "IN" operators. For example, if the
2476 ** index is on (x,y,z), then the following clauses are all
2477 ** optimized:
2478 **
2479 ** x=5
2480 ** x=5 AND y=10
2481 ** x=5 AND y<10
2482 ** x=5 AND y>5 AND y<10
2483 ** x=5 AND y=5 AND z<=10
2484 **
drh981642f2008-04-19 14:40:43 +00002485 ** The z<10 term of the following cannot be used, only
2486 ** the x=5 term:
danielk1977b790c6c2008-04-18 10:25:24 +00002487 **
2488 ** x=5 AND z<10
drhe3184742002-06-19 14:27:05 +00002489 **
drh981642f2008-04-19 14:40:43 +00002490 ** N may be zero if there are inequality constraints.
2491 ** If there are no inequality constraints, then N is at
2492 ** least one.
2493 **
drhe3184742002-06-19 14:27:05 +00002494 ** This case is also used when there are no WHERE clause
2495 ** constraints but an index is selected anyway, in order
2496 ** to force the output order to conform to an ORDER BY.
danielk1977b790c6c2008-04-18 10:25:24 +00002497 */
danielk1977751de562008-04-18 09:01:15 +00002498 int aStartOp[] = {
2499 0,
2500 0,
danielk1977b790c6c2008-04-18 10:25:24 +00002501 OP_Rewind, /* 2: (!start_constraints && startEq && !bRev) */
2502 OP_Last, /* 3: (!start_constraints && startEq && bRev) */
danielk1977751de562008-04-18 09:01:15 +00002503 OP_MoveGt, /* 4: (start_constraints && !startEq && !bRev) */
danielk1977b790c6c2008-04-18 10:25:24 +00002504 OP_MoveLt, /* 5: (start_constraints && !startEq && bRev) */
danielk1977751de562008-04-18 09:01:15 +00002505 OP_MoveGe, /* 6: (start_constraints && startEq && !bRev) */
danielk1977b790c6c2008-04-18 10:25:24 +00002506 OP_MoveLe /* 7: (start_constraints && startEq && bRev) */
danielk1977751de562008-04-18 09:01:15 +00002507 };
2508 int aEndOp[] = {
danielk1977b790c6c2008-04-18 10:25:24 +00002509 OP_Noop, /* 0: (!end_constraints) */
danielk1977751de562008-04-18 09:01:15 +00002510 OP_IdxGE, /* 1: (end_constraints && !bRev) */
2511 OP_IdxLT /* 2: (end_constraints && bRev) */
2512 };
drh51147ba2005-07-23 22:59:55 +00002513 int nEq = pLevel->nEq;
danielk1977751de562008-04-18 09:01:15 +00002514 int isMinQuery = 0; /* If this is an optimized SELECT min(x).. */
2515 int regBase; /* Base register holding constraint values */
2516 int r1; /* Temp register */
2517 WhereTerm *pRangeStart = 0; /* Inequality constraint at range start */
2518 WhereTerm *pRangeEnd = 0; /* Inequality constraint at range end */
2519 int startEq; /* True if range start uses ==, >= or <= */
2520 int endEq; /* True if range end uses ==, >= or <= */
2521 int start_constraints; /* Start of range is constrained */
2522 int k = pIdx->aiColumn[nEq]; /* Column for inequality constraints */
drh981642f2008-04-19 14:40:43 +00002523 int nConstraint; /* Number of constraint terms */
danielk1977751de562008-04-18 09:01:15 +00002524 int op;
drh487ab3c2001-11-08 00:45:21 +00002525
drh51147ba2005-07-23 22:59:55 +00002526 /* Generate code to evaluate all constraint terms using == or IN
danielk1977751de562008-04-18 09:01:15 +00002527 ** and store the values of those terms in an array of registers
2528 ** starting at regBase.
drh487ab3c2001-11-08 00:45:21 +00002529 */
drh1db639c2008-01-17 02:36:28 +00002530 regBase = codeAllEqualityTerms(pParse, pLevel, &wc, notReady, 2);
danielk1977751de562008-04-18 09:01:15 +00002531 nxt = pLevel->nxt;
drh85eeb692005-12-21 03:16:42 +00002532
danielk1977a9d1ccb2008-01-05 17:39:29 +00002533 /* If this loop satisfies a sort order (pOrderBy) request that
2534 ** was passed to this function to implement a "SELECT min(x) ..."
2535 ** query, then the caller will only allow the loop to run for
2536 ** a single iteration. This means that the first row returned
2537 ** should not have a NULL value stored in 'x'. If column 'x' is
2538 ** the first one after the nEq equality constraints in the index,
2539 ** this requires some special handling.
2540 */
drh08c88eb2008-04-10 13:33:18 +00002541 if( (wflags&WHERE_ORDERBY_MIN)!=0
danielk1977a9d1ccb2008-01-05 17:39:29 +00002542 && (pLevel->flags&WHERE_ORDERBY)
2543 && (pIdx->nColumn>nEq)
2544 && (pOrderBy->a[0].pExpr->iColumn==pIdx->aiColumn[nEq])
2545 ){
2546 isMinQuery = 1;
2547 }
2548
danielk1977b790c6c2008-04-18 10:25:24 +00002549 /* Find any inequality constraint terms for the start and end
danielk1977751de562008-04-18 09:01:15 +00002550 ** of the range.
drh487ab3c2001-11-08 00:45:21 +00002551 */
danielk1977751de562008-04-18 09:01:15 +00002552 if( pLevel->flags & WHERE_TOP_LIMIT ){
2553 pRangeEnd = findTerm(&wc, iCur, k, notReady, (WO_LT|WO_LE), pIdx);
drh487ab3c2001-11-08 00:45:21 +00002554 }
danielk1977751de562008-04-18 09:01:15 +00002555 if( pLevel->flags & WHERE_BTM_LIMIT ){
2556 pRangeStart = findTerm(&wc, iCur, k, notReady, (WO_GT|WO_GE), pIdx);
drh487ab3c2001-11-08 00:45:21 +00002557 }
2558
danielk1977751de562008-04-18 09:01:15 +00002559 /* If we are doing a reverse order scan on an ascending index, or
2560 ** a forward order scan on a descending index, interchange the
2561 ** start and end terms (pRangeStart and pRangeEnd).
drh487ab3c2001-11-08 00:45:21 +00002562 */
drh981642f2008-04-19 14:40:43 +00002563 if( bRev==(pIdx->aSortOrder[nEq]==SQLITE_SO_ASC) ){
danielk1977751de562008-04-18 09:01:15 +00002564 SWAP(WhereTerm *, pRangeEnd, pRangeStart);
drh487ab3c2001-11-08 00:45:21 +00002565 }
danielk1977751de562008-04-18 09:01:15 +00002566
drh981642f2008-04-19 14:40:43 +00002567 testcase( pRangeStart && pRangeStart->eOperator & WO_LE );
2568 testcase( pRangeStart && pRangeStart->eOperator & WO_GE );
2569 testcase( pRangeEnd && pRangeEnd->eOperator & WO_LE );
2570 testcase( pRangeEnd && pRangeEnd->eOperator & WO_GE );
2571 startEq = !pRangeStart || pRangeStart->eOperator & (WO_LE|WO_GE);
2572 endEq = !pRangeEnd || pRangeEnd->eOperator & (WO_LE|WO_GE);
2573 start_constraints = pRangeStart || nEq>0;
danielk1977751de562008-04-18 09:01:15 +00002574
2575 /* Seek the index cursor to the start of the range. */
drh981642f2008-04-19 14:40:43 +00002576 nConstraint = nEq;
danielk1977751de562008-04-18 09:01:15 +00002577 if( pRangeStart ){
2578 int dcc = pParse->disableColCache;
2579 if( pRangeEnd ){
2580 pParse->disableColCache = 1;
2581 }
2582 sqlite3ExprCode(pParse, pRangeStart->pExpr->pRight, regBase+nEq);
2583 pParse->disableColCache = dcc;
2584 sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, nxt);
drh981642f2008-04-19 14:40:43 +00002585 nConstraint++;
danielk1977751de562008-04-18 09:01:15 +00002586 }else if( isMinQuery ){
2587 sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
drh981642f2008-04-19 14:40:43 +00002588 nConstraint++;
danielk1977751de562008-04-18 09:01:15 +00002589 startEq = 0;
2590 start_constraints = 1;
2591 }
drh981642f2008-04-19 14:40:43 +00002592 codeApplyAffinity(pParse, regBase, nConstraint, pIdx);
danielk1977751de562008-04-18 09:01:15 +00002593 op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev];
drh981642f2008-04-19 14:40:43 +00002594 assert( op!=0 );
2595 testcase( op==OP_Rewind );
2596 testcase( op==OP_Last );
2597 testcase( op==OP_MoveGt );
2598 testcase( op==OP_MoveGe );
2599 testcase( op==OP_MoveLe );
2600 testcase( op==OP_MoveLt );
2601 sqlite3VdbeAddOp4(v, op, iIdxCur, nxt, regBase,
2602 (char*)nConstraint, P4_INT32);
danielk1977751de562008-04-18 09:01:15 +00002603
2604 /* Load the value for the inequality constraint at the end of the
2605 ** range (if any).
2606 */
drh981642f2008-04-19 14:40:43 +00002607 nConstraint = nEq;
danielk1977751de562008-04-18 09:01:15 +00002608 if( pRangeEnd ){
2609 sqlite3ExprCode(pParse, pRangeEnd->pExpr->pRight, regBase+nEq);
2610 sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, nxt);
danielk1977b790c6c2008-04-18 10:25:24 +00002611 codeApplyAffinity(pParse, regBase, nEq+1, pIdx);
drh981642f2008-04-19 14:40:43 +00002612 nConstraint++;
danielk1977751de562008-04-18 09:01:15 +00002613 }
danielk1977751de562008-04-18 09:01:15 +00002614
2615 /* Top of the loop body */
2616 pLevel->p2 = sqlite3VdbeCurrentAddr(v);
2617
2618 /* Check if the index cursor is past the end of the range. */
drh981642f2008-04-19 14:40:43 +00002619 op = aEndOp[(pRangeEnd || nEq) * (1 + bRev)];
2620 testcase( op==OP_Noop );
2621 testcase( op==OP_IdxGE );
2622 testcase( op==OP_IdxLT );
2623 sqlite3VdbeAddOp4(v, op, iIdxCur, nxt, regBase,
2624 (char*)nConstraint, P4_INT32);
danielk1977751de562008-04-18 09:01:15 +00002625 sqlite3VdbeChangeP5(v, endEq!=bRev);
2626
drh981642f2008-04-19 14:40:43 +00002627 /* If there are inequality constraints, check that the value
2628 ** of the table column that the inequality contrains is not NULL.
danielk1977751de562008-04-18 09:01:15 +00002629 ** If it is, jump to the next iteration of the loop.
2630 */
drh1db639c2008-01-17 02:36:28 +00002631 r1 = sqlite3GetTempReg(pParse);
drh981642f2008-04-19 14:40:43 +00002632 testcase( pLevel->flags & WHERE_BTM_LIMIT );
2633 testcase( pLevel->flags & WHERE_TOP_LIMIT );
danielk1977751de562008-04-18 09:01:15 +00002634 if( pLevel->flags & (WHERE_BTM_LIMIT|WHERE_TOP_LIMIT) ){
drh1db639c2008-01-17 02:36:28 +00002635 sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, nEq, r1);
2636 sqlite3VdbeAddOp2(v, OP_IsNull, r1, cont);
drh50b39962006-10-28 00:28:09 +00002637 }
danielk1977751de562008-04-18 09:01:15 +00002638
2639 /* Seek the table cursor, if required */
drhe6f85e72004-12-25 01:03:13 +00002640 if( !omitTable ){
drh1db639c2008-01-17 02:36:28 +00002641 sqlite3VdbeAddOp2(v, OP_IdxRowid, iIdxCur, r1);
drh91fd4d42008-01-19 20:11:25 +00002642 sqlite3VdbeAddOp3(v, OP_MoveGe, iCur, 0, r1); /* Deferred seek */
drh487ab3c2001-11-08 00:45:21 +00002643 }
drh1db639c2008-01-17 02:36:28 +00002644 sqlite3ReleaseTempReg(pParse, r1);
drh487ab3c2001-11-08 00:45:21 +00002645
danielk1977751de562008-04-18 09:01:15 +00002646 /* Record the instruction used to terminate the loop. Disable
2647 ** WHERE clause terms made redundant by the index range scan.
drh487ab3c2001-11-08 00:45:21 +00002648 */
drhfe05af82005-07-21 03:14:59 +00002649 pLevel->op = bRev ? OP_Prev : OP_Next;
drh9012bcb2004-12-19 00:11:35 +00002650 pLevel->p1 = iIdxCur;
danielk1977751de562008-04-18 09:01:15 +00002651 disableTerm(pLevel, pRangeStart);
2652 disableTerm(pLevel, pRangeEnd);
drhfe05af82005-07-21 03:14:59 +00002653 }else{
drh981642f2008-04-19 14:40:43 +00002654 /* Case 4: There is no usable index. We must do a complete
drhfe05af82005-07-21 03:14:59 +00002655 ** scan of the entire table.
2656 */
drhfe05af82005-07-21 03:14:59 +00002657 assert( omitTable==0 );
drha6110402005-07-28 20:51:19 +00002658 assert( bRev==0 );
2659 pLevel->op = OP_Next;
drhfe05af82005-07-21 03:14:59 +00002660 pLevel->p1 = iCur;
drh66a51672008-01-03 00:01:23 +00002661 pLevel->p2 = 1 + sqlite3VdbeAddOp2(v, OP_Rewind, iCur, brk);
drh75897232000-05-29 14:26:00 +00002662 }
drhfe05af82005-07-21 03:14:59 +00002663 notReady &= ~getMask(&maskSet, iCur);
drh75897232000-05-29 14:26:00 +00002664
2665 /* Insert code to test every subexpression that can be completely
2666 ** computed using the current set of tables.
2667 */
drh0fcef5e2005-07-19 17:38:22 +00002668 for(pTerm=wc.a, j=wc.nTerm; j>0; j--, pTerm++){
2669 Expr *pE;
drh981642f2008-04-19 14:40:43 +00002670 testcase( pTerm->flags & TERM_VIRTUAL );
2671 testcase( pTerm->flags & TERM_CODED );
drh0fcef5e2005-07-19 17:38:22 +00002672 if( pTerm->flags & (TERM_VIRTUAL|TERM_CODED) ) continue;
drhfe05af82005-07-21 03:14:59 +00002673 if( (pTerm->prereqAll & notReady)!=0 ) continue;
drh0fcef5e2005-07-19 17:38:22 +00002674 pE = pTerm->pExpr;
2675 assert( pE!=0 );
drh392e5972005-07-08 14:14:22 +00002676 if( pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin) ){
drh1f162302002-10-27 19:35:33 +00002677 continue;
2678 }
drh35573352008-01-08 23:54:25 +00002679 sqlite3ExprIfFalse(pParse, pE, cont, SQLITE_JUMPIFNULL);
drh0fcef5e2005-07-19 17:38:22 +00002680 pTerm->flags |= TERM_CODED;
drh75897232000-05-29 14:26:00 +00002681 }
drhad2d8302002-05-24 20:31:36 +00002682
2683 /* For a LEFT OUTER JOIN, generate code that will record the fact that
2684 ** at least one row of the right table has matched the left table.
2685 */
2686 if( pLevel->iLeftJoin ){
danielk19774adee202004-05-08 08:23:19 +00002687 pLevel->top = sqlite3VdbeCurrentAddr(v);
drh4c583122008-01-04 22:01:03 +00002688 sqlite3VdbeAddOp2(v, OP_Integer, 1, pLevel->iLeftJoin);
drhd4e70eb2008-01-02 00:34:36 +00002689 VdbeComment((v, "record LEFT JOIN hit"));
drhe55cbd72008-03-31 23:48:03 +00002690 sqlite3ExprClearColumnCache(pParse, pLevel->iTabCur);
2691 sqlite3ExprClearColumnCache(pParse, pLevel->iIdxCur);
drh0aa74ed2005-07-16 13:33:20 +00002692 for(pTerm=wc.a, j=0; j<wc.nTerm; j++, pTerm++){
drh981642f2008-04-19 14:40:43 +00002693 testcase( pTerm->flags & TERM_VIRTUAL );
2694 testcase( pTerm->flags & TERM_CODED );
drh0fcef5e2005-07-19 17:38:22 +00002695 if( pTerm->flags & (TERM_VIRTUAL|TERM_CODED) ) continue;
drhfe05af82005-07-21 03:14:59 +00002696 if( (pTerm->prereqAll & notReady)!=0 ) continue;
drh0fcef5e2005-07-19 17:38:22 +00002697 assert( pTerm->pExpr );
drh35573352008-01-08 23:54:25 +00002698 sqlite3ExprIfFalse(pParse, pTerm->pExpr, cont, SQLITE_JUMPIFNULL);
drh0fcef5e2005-07-19 17:38:22 +00002699 pTerm->flags |= TERM_CODED;
drh1cc093c2002-06-24 22:01:57 +00002700 }
drhad2d8302002-05-24 20:31:36 +00002701 }
drh75897232000-05-29 14:26:00 +00002702 }
drh7ec764a2005-07-21 03:48:20 +00002703
2704#ifdef SQLITE_TEST /* For testing and debugging use only */
2705 /* Record in the query plan information about the current table
2706 ** and the index used to access it (if any). If the table itself
2707 ** is not used, its name is just '{}'. If no index is used
2708 ** the index is listed as "{}". If the primary key is used the
2709 ** index name is '*'.
2710 */
2711 for(i=0; i<pTabList->nSrc; i++){
2712 char *z;
2713 int n;
drh7ec764a2005-07-21 03:48:20 +00002714 pLevel = &pWInfo->a[i];
drh29dda4a2005-07-21 18:23:20 +00002715 pTabItem = &pTabList->a[pLevel->iFrom];
drh7ec764a2005-07-21 03:48:20 +00002716 z = pTabItem->zAlias;
2717 if( z==0 ) z = pTabItem->pTab->zName;
2718 n = strlen(z);
2719 if( n+nQPlan < sizeof(sqlite3_query_plan)-10 ){
2720 if( pLevel->flags & WHERE_IDX_ONLY ){
drh5bb3eb92007-05-04 13:15:55 +00002721 memcpy(&sqlite3_query_plan[nQPlan], "{}", 2);
drh7ec764a2005-07-21 03:48:20 +00002722 nQPlan += 2;
2723 }else{
drh5bb3eb92007-05-04 13:15:55 +00002724 memcpy(&sqlite3_query_plan[nQPlan], z, n);
drh7ec764a2005-07-21 03:48:20 +00002725 nQPlan += n;
2726 }
2727 sqlite3_query_plan[nQPlan++] = ' ';
2728 }
drh981642f2008-04-19 14:40:43 +00002729 testcase( pLevel->flags & WHERE_ROWID_EQ );
2730 testcase( pLevel->flags & WHERE_ROWID_RANGE );
drh7ec764a2005-07-21 03:48:20 +00002731 if( pLevel->flags & (WHERE_ROWID_EQ|WHERE_ROWID_RANGE) ){
drh5bb3eb92007-05-04 13:15:55 +00002732 memcpy(&sqlite3_query_plan[nQPlan], "* ", 2);
drh7ec764a2005-07-21 03:48:20 +00002733 nQPlan += 2;
2734 }else if( pLevel->pIdx==0 ){
drh5bb3eb92007-05-04 13:15:55 +00002735 memcpy(&sqlite3_query_plan[nQPlan], "{} ", 3);
drh7ec764a2005-07-21 03:48:20 +00002736 nQPlan += 3;
2737 }else{
2738 n = strlen(pLevel->pIdx->zName);
2739 if( n+nQPlan < sizeof(sqlite3_query_plan)-2 ){
drh5bb3eb92007-05-04 13:15:55 +00002740 memcpy(&sqlite3_query_plan[nQPlan], pLevel->pIdx->zName, n);
drh7ec764a2005-07-21 03:48:20 +00002741 nQPlan += n;
2742 sqlite3_query_plan[nQPlan++] = ' ';
2743 }
2744 }
2745 }
2746 while( nQPlan>0 && sqlite3_query_plan[nQPlan-1]==' ' ){
2747 sqlite3_query_plan[--nQPlan] = 0;
2748 }
2749 sqlite3_query_plan[nQPlan] = 0;
2750 nQPlan = 0;
2751#endif /* SQLITE_TEST // Testing and debugging use only */
2752
drh29dda4a2005-07-21 18:23:20 +00002753 /* Record the continuation address in the WhereInfo structure. Then
2754 ** clean up and return.
2755 */
drh75897232000-05-29 14:26:00 +00002756 pWInfo->iContinue = cont;
drh0aa74ed2005-07-16 13:33:20 +00002757 whereClauseClear(&wc);
drh75897232000-05-29 14:26:00 +00002758 return pWInfo;
drhe23399f2005-07-22 00:31:39 +00002759
2760 /* Jump here if malloc fails */
2761whereBeginNoMem:
2762 whereClauseClear(&wc);
drh9eff6162006-06-12 21:59:13 +00002763 whereInfoFree(pWInfo);
drhe23399f2005-07-22 00:31:39 +00002764 return 0;
drh75897232000-05-29 14:26:00 +00002765}
2766
2767/*
drhc27a1ce2002-06-14 20:58:45 +00002768** Generate the end of the WHERE loop. See comments on
danielk19774adee202004-05-08 08:23:19 +00002769** sqlite3WhereBegin() for additional information.
drh75897232000-05-29 14:26:00 +00002770*/
danielk19774adee202004-05-08 08:23:19 +00002771void sqlite3WhereEnd(WhereInfo *pWInfo){
drh75897232000-05-29 14:26:00 +00002772 Vdbe *v = pWInfo->pParse->pVdbe;
drh19a775c2000-06-05 18:54:46 +00002773 int i;
drh6b563442001-11-07 16:48:26 +00002774 WhereLevel *pLevel;
drhad3cab52002-05-24 02:04:32 +00002775 SrcList *pTabList = pWInfo->pTabList;
drh19a775c2000-06-05 18:54:46 +00002776
drh9012bcb2004-12-19 00:11:35 +00002777 /* Generate loop termination code.
2778 */
drhe55cbd72008-03-31 23:48:03 +00002779 sqlite3ExprClearColumnCache(pWInfo->pParse, -1);
drhad3cab52002-05-24 02:04:32 +00002780 for(i=pTabList->nSrc-1; i>=0; i--){
drh6b563442001-11-07 16:48:26 +00002781 pLevel = &pWInfo->a[i];
danielk19774adee202004-05-08 08:23:19 +00002782 sqlite3VdbeResolveLabel(v, pLevel->cont);
drh6b563442001-11-07 16:48:26 +00002783 if( pLevel->op!=OP_Noop ){
drh66a51672008-01-03 00:01:23 +00002784 sqlite3VdbeAddOp2(v, pLevel->op, pLevel->p1, pLevel->p2);
drh19a775c2000-06-05 18:54:46 +00002785 }
drhe23399f2005-07-22 00:31:39 +00002786 if( pLevel->nIn ){
drh72e8fa42007-03-28 14:30:06 +00002787 struct InLoop *pIn;
drhe23399f2005-07-22 00:31:39 +00002788 int j;
drh72e8fa42007-03-28 14:30:06 +00002789 sqlite3VdbeResolveLabel(v, pLevel->nxt);
2790 for(j=pLevel->nIn, pIn=&pLevel->aInLoop[j-1]; j>0; j--, pIn--){
2791 sqlite3VdbeJumpHere(v, pIn->topAddr+1);
drh66a51672008-01-03 00:01:23 +00002792 sqlite3VdbeAddOp2(v, OP_Next, pIn->iCur, pIn->topAddr);
drh72e8fa42007-03-28 14:30:06 +00002793 sqlite3VdbeJumpHere(v, pIn->topAddr-1);
drhe23399f2005-07-22 00:31:39 +00002794 }
drh17435752007-08-16 04:30:38 +00002795 sqlite3_free(pLevel->aInLoop);
drhd99f7062002-06-08 23:25:08 +00002796 }
drh72e8fa42007-03-28 14:30:06 +00002797 sqlite3VdbeResolveLabel(v, pLevel->brk);
drhad2d8302002-05-24 20:31:36 +00002798 if( pLevel->iLeftJoin ){
2799 int addr;
drh3c84ddf2008-01-09 02:15:38 +00002800 addr = sqlite3VdbeAddOp1(v, OP_IfPos, pLevel->iLeftJoin);
2801 sqlite3VdbeAddOp1(v, OP_NullRow, pTabList->a[i].iCursor);
drh9012bcb2004-12-19 00:11:35 +00002802 if( pLevel->iIdxCur>=0 ){
drh3c84ddf2008-01-09 02:15:38 +00002803 sqlite3VdbeAddOp1(v, OP_NullRow, pLevel->iIdxCur);
drh7f09b3e2002-08-13 13:15:49 +00002804 }
drh66a51672008-01-03 00:01:23 +00002805 sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->top);
drhd654be82005-09-20 17:42:23 +00002806 sqlite3VdbeJumpHere(v, addr);
drhad2d8302002-05-24 20:31:36 +00002807 }
drh19a775c2000-06-05 18:54:46 +00002808 }
drh9012bcb2004-12-19 00:11:35 +00002809
2810 /* The "break" point is here, just past the end of the outer loop.
2811 ** Set it.
2812 */
danielk19774adee202004-05-08 08:23:19 +00002813 sqlite3VdbeResolveLabel(v, pWInfo->iBreak);
drh9012bcb2004-12-19 00:11:35 +00002814
drh29dda4a2005-07-21 18:23:20 +00002815 /* Close all of the cursors that were opened by sqlite3WhereBegin.
drh9012bcb2004-12-19 00:11:35 +00002816 */
drh29dda4a2005-07-21 18:23:20 +00002817 for(i=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){
2818 struct SrcList_item *pTabItem = &pTabList->a[pLevel->iFrom];
drh9012bcb2004-12-19 00:11:35 +00002819 Table *pTab = pTabItem->pTab;
drh5cf590c2003-04-24 01:45:04 +00002820 assert( pTab!=0 );
drhb9bb7c12006-06-11 23:41:55 +00002821 if( pTab->isEphem || pTab->pSelect ) continue;
drh08c88eb2008-04-10 13:33:18 +00002822 if( !pWInfo->okOnePass && (pLevel->flags & WHERE_IDX_ONLY)==0 ){
drh3c84ddf2008-01-09 02:15:38 +00002823 sqlite3VdbeAddOp1(v, OP_Close, pTabItem->iCursor);
drh9012bcb2004-12-19 00:11:35 +00002824 }
drh6b563442001-11-07 16:48:26 +00002825 if( pLevel->pIdx!=0 ){
drh3c84ddf2008-01-09 02:15:38 +00002826 sqlite3VdbeAddOp1(v, OP_Close, pLevel->iIdxCur);
drh9012bcb2004-12-19 00:11:35 +00002827 }
2828
danielk197721de2e72007-11-29 17:43:27 +00002829 /* If this scan uses an index, make code substitutions to read data
2830 ** from the index in preference to the table. Sometimes, this means
2831 ** the table need never be read from. This is a performance boost,
2832 ** as the vdbe level waits until the table is read before actually
2833 ** seeking the table cursor to the record corresponding to the current
2834 ** position in the index.
drh9012bcb2004-12-19 00:11:35 +00002835 **
2836 ** Calls to the code generator in between sqlite3WhereBegin and
2837 ** sqlite3WhereEnd will have created code that references the table
2838 ** directly. This loop scans all that code looking for opcodes
2839 ** that reference the table and converts them into opcodes that
2840 ** reference the index.
2841 */
danielk197721de2e72007-11-29 17:43:27 +00002842 if( pLevel->pIdx ){
danielk1977f0113002006-01-24 12:09:17 +00002843 int k, j, last;
drh9012bcb2004-12-19 00:11:35 +00002844 VdbeOp *pOp;
2845 Index *pIdx = pLevel->pIdx;
danielk197721de2e72007-11-29 17:43:27 +00002846 int useIndexOnly = pLevel->flags & WHERE_IDX_ONLY;
drh9012bcb2004-12-19 00:11:35 +00002847
2848 assert( pIdx!=0 );
2849 pOp = sqlite3VdbeGetOp(v, pWInfo->iTop);
2850 last = sqlite3VdbeCurrentAddr(v);
danielk1977f0113002006-01-24 12:09:17 +00002851 for(k=pWInfo->iTop; k<last; k++, pOp++){
drh9012bcb2004-12-19 00:11:35 +00002852 if( pOp->p1!=pLevel->iTabCur ) continue;
2853 if( pOp->opcode==OP_Column ){
drh9012bcb2004-12-19 00:11:35 +00002854 for(j=0; j<pIdx->nColumn; j++){
2855 if( pOp->p2==pIdx->aiColumn[j] ){
2856 pOp->p2 = j;
danielk197721de2e72007-11-29 17:43:27 +00002857 pOp->p1 = pLevel->iIdxCur;
drh9012bcb2004-12-19 00:11:35 +00002858 break;
2859 }
2860 }
danielk197721de2e72007-11-29 17:43:27 +00002861 assert(!useIndexOnly || j<pIdx->nColumn);
drhf0863fe2005-06-12 21:35:51 +00002862 }else if( pOp->opcode==OP_Rowid ){
drh9012bcb2004-12-19 00:11:35 +00002863 pOp->p1 = pLevel->iIdxCur;
drhf0863fe2005-06-12 21:35:51 +00002864 pOp->opcode = OP_IdxRowid;
danielk197721de2e72007-11-29 17:43:27 +00002865 }else if( pOp->opcode==OP_NullRow && useIndexOnly ){
danielk19776c18b6e2005-01-30 09:17:58 +00002866 pOp->opcode = OP_Noop;
drh9012bcb2004-12-19 00:11:35 +00002867 }
2868 }
drh6b563442001-11-07 16:48:26 +00002869 }
drh19a775c2000-06-05 18:54:46 +00002870 }
drh9012bcb2004-12-19 00:11:35 +00002871
2872 /* Final cleanup
2873 */
drh9eff6162006-06-12 21:59:13 +00002874 whereInfoFree(pWInfo);
drh75897232000-05-29 14:26:00 +00002875 return;
2876}