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Overview
Comment: | Begin an effort to enhance the query planner to do a better job with OR terms in the WHERE clause. This change allows ANDs outside of the OR to be factored into the OR terms if that is helpful in finding better indices. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | or-opt |
Files: | files | file ages | folders |
SHA1: |
876bd21aaac444c7e056730e35696a74 |
User & Date: | drh 2011-10-07 13:33:10.760 |
Context
2011-10-07
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14:40 | Prevent infinite recursion of in the query planner for some pathological test cases by disabling OR-clause processing upon first recursion. (check-in: 9fca05eac5 user: drh tags: or-opt) | |
13:33 | Begin an effort to enhance the query planner to do a better job with OR terms in the WHERE clause. This change allows ANDs outside of the OR to be factored into the OR terms if that is helpful in finding better indices. (check-in: 876bd21aaa user: drh tags: or-opt) | |
12:59 | Enhance the sqlite3_data_count() routine so that it can be used to determine if SQLITE_DONE has been seen on the prepared statement. (check-in: 9913996e7b user: drh tags: trunk) | |
Changes
Changes to src/where.c.
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123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 | #else # define TERM_VNULL 0x00 /* Disabled if not using stat3 */ #endif /* ** An instance of the following structure holds all information about a ** WHERE clause. Mostly this is a container for one or more WhereTerms. */ struct WhereClause { Parse *pParse; /* The parser context */ WhereMaskSet *pMaskSet; /* Mapping of table cursor numbers to bitmasks */ Bitmask vmask; /* Bitmask identifying virtual table cursors */ u8 op; /* Split operator. TK_AND or TK_OR */ int nTerm; /* Number of terms */ int nSlot; /* Number of entries in a[] */ WhereTerm *a; /* Each a[] describes a term of the WHERE cluase */ #if defined(SQLITE_SMALL_STACK) WhereTerm aStatic[1]; /* Initial static space for a[] */ #else | > > > > > > > > > | 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 | #else # define TERM_VNULL 0x00 /* Disabled if not using stat3 */ #endif /* ** An instance of the following structure holds all information about a ** WHERE clause. Mostly this is a container for one or more WhereTerms. ** ** Explanation of pOuter: For a WHERE clause of the form ** ** a AND ((b AND c) OR (d AND e)) AND f ** ** There are separate WhereClause objects for the whole clause and for ** the subclauses "(b AND c)" and "(d AND e)". The pOuter field of the ** subclauses points to the WhereClause object for the whole clause. */ struct WhereClause { Parse *pParse; /* The parser context */ WhereMaskSet *pMaskSet; /* Mapping of table cursor numbers to bitmasks */ Bitmask vmask; /* Bitmask identifying virtual table cursors */ WhereClause *pOuter; /* Outer conjunction */ u8 op; /* Split operator. TK_AND or TK_OR */ int nTerm; /* Number of terms */ int nSlot; /* Number of entries in a[] */ WhereTerm *a; /* Each a[] describes a term of the WHERE cluase */ #if defined(SQLITE_SMALL_STACK) WhereTerm aStatic[1]; /* Initial static space for a[] */ #else |
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261 262 263 264 265 266 267 268 269 270 271 272 273 274 | static void whereClauseInit( WhereClause *pWC, /* The WhereClause to be initialized */ Parse *pParse, /* The parsing context */ WhereMaskSet *pMaskSet /* Mapping from table cursor numbers to bitmasks */ ){ pWC->pParse = pParse; pWC->pMaskSet = pMaskSet; pWC->nTerm = 0; pWC->nSlot = ArraySize(pWC->aStatic); pWC->a = pWC->aStatic; pWC->vmask = 0; } /* Forward reference */ | > | 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 | static void whereClauseInit( WhereClause *pWC, /* The WhereClause to be initialized */ Parse *pParse, /* The parsing context */ WhereMaskSet *pMaskSet /* Mapping from table cursor numbers to bitmasks */ ){ pWC->pParse = pParse; pWC->pMaskSet = pMaskSet; pWC->pOuter = 0; pWC->nTerm = 0; pWC->nSlot = ArraySize(pWC->aStatic); pWC->a = pWC->aStatic; pWC->vmask = 0; } /* Forward reference */ |
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580 581 582 583 584 585 586 | u32 op, /* Mask of WO_xx values describing operator */ Index *pIdx /* Must be compatible with this index, if not NULL */ ){ WhereTerm *pTerm; int k; assert( iCur>=0 ); op &= WO_ALL; | > | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | > | 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 | u32 op, /* Mask of WO_xx values describing operator */ Index *pIdx /* Must be compatible with this index, if not NULL */ ){ WhereTerm *pTerm; int k; assert( iCur>=0 ); op &= WO_ALL; for(; pWC; pWC=pWC->pOuter){ for(pTerm=pWC->a, k=pWC->nTerm; k; k--, pTerm++){ if( pTerm->leftCursor==iCur && (pTerm->prereqRight & notReady)==0 && pTerm->u.leftColumn==iColumn && (pTerm->eOperator & op)!=0 ){ if( pIdx && pTerm->eOperator!=WO_ISNULL ){ Expr *pX = pTerm->pExpr; CollSeq *pColl; char idxaff; int j; Parse *pParse = pWC->pParse; idxaff = pIdx->pTable->aCol[iColumn].affinity; if( !sqlite3IndexAffinityOk(pX, idxaff) ) continue; /* Figure out the collation sequence required from an index for ** it to be useful for optimising expression pX. Store this ** value in variable pColl. */ assert(pX->pLeft); pColl = sqlite3BinaryCompareCollSeq(pParse, pX->pLeft, pX->pRight); assert(pColl || pParse->nErr); for(j=0; pIdx->aiColumn[j]!=iColumn; j++){ if( NEVER(j>=pIdx->nColumn) ) return 0; } if( pColl && sqlite3StrICmp(pColl->zName, pIdx->azColl[j]) ) continue; } return pTerm; } } } return 0; } /* Forward reference */ static void exprAnalyze(SrcList*, WhereClause*, int); |
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903 904 905 906 907 908 909 910 911 912 913 914 915 916 | pOrTerm->u.pAndInfo = pAndInfo; pOrTerm->wtFlags |= TERM_ANDINFO; pOrTerm->eOperator = WO_AND; pAndWC = &pAndInfo->wc; whereClauseInit(pAndWC, pWC->pParse, pMaskSet); whereSplit(pAndWC, pOrTerm->pExpr, TK_AND); exprAnalyzeAll(pSrc, pAndWC); testcase( db->mallocFailed ); if( !db->mallocFailed ){ for(j=0, pAndTerm=pAndWC->a; j<pAndWC->nTerm; j++, pAndTerm++){ assert( pAndTerm->pExpr ); if( allowedOp(pAndTerm->pExpr->op) ){ b |= getMask(pMaskSet, pAndTerm->leftCursor); } | > | 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 | pOrTerm->u.pAndInfo = pAndInfo; pOrTerm->wtFlags |= TERM_ANDINFO; pOrTerm->eOperator = WO_AND; pAndWC = &pAndInfo->wc; whereClauseInit(pAndWC, pWC->pParse, pMaskSet); whereSplit(pAndWC, pOrTerm->pExpr, TK_AND); exprAnalyzeAll(pSrc, pAndWC); pAndWC->pOuter = pWC; testcase( db->mallocFailed ); if( !db->mallocFailed ){ for(j=0, pAndTerm=pAndWC->a; j<pAndWC->nTerm; j++, pAndTerm++){ assert( pAndTerm->pExpr ); if( allowedOp(pAndTerm->pExpr->op) ){ b |= getMask(pMaskSet, pAndTerm->leftCursor); } |
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1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 | if( pOrTerm->eOperator==WO_AND ){ WhereClause *pAndWC = &pOrTerm->u.pAndInfo->wc; bestIndex(pParse, pAndWC, pSrc, notReady, notValid, 0, &sTermCost); }else if( pOrTerm->leftCursor==iCur ){ WhereClause tempWC; tempWC.pParse = pWC->pParse; tempWC.pMaskSet = pWC->pMaskSet; tempWC.op = TK_AND; tempWC.a = pOrTerm; tempWC.nTerm = 1; bestIndex(pParse, &tempWC, pSrc, notReady, notValid, 0, &sTermCost); }else{ continue; } | > | 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 | if( pOrTerm->eOperator==WO_AND ){ WhereClause *pAndWC = &pOrTerm->u.pAndInfo->wc; bestIndex(pParse, pAndWC, pSrc, notReady, notValid, 0, &sTermCost); }else if( pOrTerm->leftCursor==iCur ){ WhereClause tempWC; tempWC.pParse = pWC->pParse; tempWC.pMaskSet = pWC->pMaskSet; tempWC.pOuter = pWC; tempWC.op = TK_AND; tempWC.a = pOrTerm; tempWC.nTerm = 1; bestIndex(pParse, &tempWC, pSrc, notReady, notValid, 0, &sTermCost); }else{ continue; } |
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3765 3766 3767 3768 3769 3770 3771 | ** Generate code for the start of the iLevel-th loop in the WHERE clause ** implementation described by pWInfo. */ static Bitmask codeOneLoopStart( WhereInfo *pWInfo, /* Complete information about the WHERE clause */ int iLevel, /* Which level of pWInfo->a[] should be coded */ u16 wctrlFlags, /* One of the WHERE_* flags defined in sqliteInt.h */ | | > | 3779 3780 3781 3782 3783 3784 3785 3786 3787 3788 3789 3790 3791 3792 3793 3794 | ** Generate code for the start of the iLevel-th loop in the WHERE clause ** implementation described by pWInfo. */ static Bitmask codeOneLoopStart( WhereInfo *pWInfo, /* Complete information about the WHERE clause */ int iLevel, /* Which level of pWInfo->a[] should be coded */ u16 wctrlFlags, /* One of the WHERE_* flags defined in sqliteInt.h */ Bitmask notReady, /* Which tables are currently available */ Expr *pWhere /* Complete WHERE clause */ ){ int j, k; /* Loop counters */ int iCur; /* The VDBE cursor for the table */ int addrNxt; /* Where to jump to continue with the next IN case */ int omitTable; /* True if we use the index only */ int bRev; /* True if we need to scan in reverse order */ WhereLevel *pLevel; /* The where level to be coded */ |
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4247 4248 4249 4250 4251 4252 4253 | int regReturn = ++pParse->nMem; /* Register used with OP_Gosub */ int regRowset = 0; /* Register for RowSet object */ int regRowid = 0; /* Register holding rowid */ int iLoopBody = sqlite3VdbeMakeLabel(v); /* Start of loop body */ int iRetInit; /* Address of regReturn init */ int untestedTerms = 0; /* Some terms not completely tested */ | | > | 4262 4263 4264 4265 4266 4267 4268 4269 4270 4271 4272 4273 4274 4275 4276 4277 | int regReturn = ++pParse->nMem; /* Register used with OP_Gosub */ int regRowset = 0; /* Register for RowSet object */ int regRowid = 0; /* Register holding rowid */ int iLoopBody = sqlite3VdbeMakeLabel(v); /* Start of loop body */ int iRetInit; /* Address of regReturn init */ int untestedTerms = 0; /* Some terms not completely tested */ int ii; /* Loop counter */ Expr *pAndExpr = 0; /* An ".. AND (...)" expression */ pTerm = pLevel->plan.u.pTerm; assert( pTerm!=0 ); assert( pTerm->eOperator==WO_OR ); assert( (pTerm->wtFlags & TERM_ORINFO)!=0 ); pOrWc = &pTerm->u.pOrInfo->wc; pLevel->op = OP_Return; |
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4296 4297 4298 4299 4300 4301 4302 4303 4304 4305 4306 4307 4308 | */ if( (wctrlFlags & WHERE_DUPLICATES_OK)==0 ){ regRowset = ++pParse->nMem; regRowid = ++pParse->nMem; sqlite3VdbeAddOp2(v, OP_Null, 0, regRowset); } iRetInit = sqlite3VdbeAddOp2(v, OP_Integer, 0, regReturn); for(ii=0; ii<pOrWc->nTerm; ii++){ WhereTerm *pOrTerm = &pOrWc->a[ii]; if( pOrTerm->leftCursor==iCur || pOrTerm->eOperator==WO_AND ){ WhereInfo *pSubWInfo; /* Info for single OR-term scan */ /* Loop through table entries that match term pOrTerm. */ | > > > > > > > > > > > > > > > | | 4312 4313 4314 4315 4316 4317 4318 4319 4320 4321 4322 4323 4324 4325 4326 4327 4328 4329 4330 4331 4332 4333 4334 4335 4336 4337 4338 4339 4340 4341 4342 4343 4344 4345 4346 4347 | */ if( (wctrlFlags & WHERE_DUPLICATES_OK)==0 ){ regRowset = ++pParse->nMem; regRowid = ++pParse->nMem; sqlite3VdbeAddOp2(v, OP_Null, 0, regRowset); } iRetInit = sqlite3VdbeAddOp2(v, OP_Integer, 0, regReturn); /* If the original WHERE clause is z of the form: (x1 OR x2 OR ...) AND y ** Then for every term xN, evaluate as the subexpression: xN AND z ** That way, terms in y that are factored into the disjunction will ** be picked up by the recursive calls to sqlite3WhereBegin() below. */ if( pWC->nTerm>1 ){ pAndExpr = sqlite3ExprAlloc(pParse->db, TK_AND, 0, 0); pAndExpr->pRight = pWhere; } for(ii=0; ii<pOrWc->nTerm; ii++){ WhereTerm *pOrTerm = &pOrWc->a[ii]; if( pOrTerm->leftCursor==iCur || pOrTerm->eOperator==WO_AND ){ WhereInfo *pSubWInfo; /* Info for single OR-term scan */ Expr *pOrExpr = pOrTerm->pExpr; if( pAndExpr ){ pAndExpr->pLeft = pOrExpr; pOrExpr = pAndExpr; } /* Loop through table entries that match term pOrTerm. */ pSubWInfo = sqlite3WhereBegin(pParse, pOrTab, pOrExpr, 0, 0, WHERE_OMIT_OPEN | WHERE_OMIT_CLOSE | WHERE_FORCE_TABLE | WHERE_ONETABLE_ONLY); if( pSubWInfo ){ explainOneScan( pParse, pOrTab, &pSubWInfo->a[0], iLevel, pLevel->iFrom, 0 ); if( (wctrlFlags & WHERE_DUPLICATES_OK)==0 ){ |
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4331 4332 4333 4334 4335 4336 4337 4338 4339 4340 4341 4342 4343 4344 | if( pSubWInfo->untestedTerms ) untestedTerms = 1; /* Finish the loop through table entries that match term pOrTerm. */ sqlite3WhereEnd(pSubWInfo); } } } sqlite3VdbeChangeP1(v, iRetInit, sqlite3VdbeCurrentAddr(v)); sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->addrBrk); sqlite3VdbeResolveLabel(v, iLoopBody); if( pWInfo->nLevel>1 ) sqlite3StackFree(pParse->db, pOrTab); if( !untestedTerms ) disableTerm(pLevel, pTerm); }else | > | 4362 4363 4364 4365 4366 4367 4368 4369 4370 4371 4372 4373 4374 4375 4376 | if( pSubWInfo->untestedTerms ) untestedTerms = 1; /* Finish the loop through table entries that match term pOrTerm. */ sqlite3WhereEnd(pSubWInfo); } } } sqlite3DbFree(pParse->db, pAndExpr); sqlite3VdbeChangeP1(v, iRetInit, sqlite3VdbeCurrentAddr(v)); sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->addrBrk); sqlite3VdbeResolveLabel(v, iLoopBody); if( pWInfo->nLevel>1 ) sqlite3StackFree(pParse->db, pOrTab); if( !untestedTerms ) disableTerm(pLevel, pTerm); }else |
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4985 4986 4987 4988 4989 4990 4991 | ** loop below generates code for a single nested loop of the VM ** program. */ notReady = ~(Bitmask)0; for(i=0; i<nTabList; i++){ pLevel = &pWInfo->a[i]; explainOneScan(pParse, pTabList, pLevel, i, pLevel->iFrom, wctrlFlags); | | | 5017 5018 5019 5020 5021 5022 5023 5024 5025 5026 5027 5028 5029 5030 5031 | ** loop below generates code for a single nested loop of the VM ** program. */ notReady = ~(Bitmask)0; for(i=0; i<nTabList; i++){ pLevel = &pWInfo->a[i]; explainOneScan(pParse, pTabList, pLevel, i, pLevel->iFrom, wctrlFlags); notReady = codeOneLoopStart(pWInfo, i, wctrlFlags, notReady, pWhere); pWInfo->iContinue = pLevel->addrCont; } #ifdef SQLITE_TEST /* For testing and debugging use only */ /* Record in the query plan information about the current table ** and the index used to access it (if any). If the table itself ** is not used, its name is just '{}'. If no index is used |
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