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Overview
Comment: | Avoid generating hints using constraints that are also used to initialize the cursor, since presumably the cursor already knows about those constraints. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | cursor-hints |
Files: | files | file ages | folders |
SHA1: |
142b048ac778620dd4e448c2e969982e |
User & Date: | drh 2015-08-17 17:19:28.483 |
Context
2015-08-18
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15:58 | Provide hints for all terms in a range constraint if there are any equality terms anywhere in the constraint. Range constraint terms are only omitted for a pure range constraint with no equality prefix. (check-in: b5897bc0f0 user: drh tags: cursor-hints) | |
2015-08-17
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17:19 | Avoid generating hints using constraints that are also used to initialize the cursor, since presumably the cursor already knows about those constraints. (check-in: 142b048ac7 user: drh tags: cursor-hints) | |
2015-08-15
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00:51 | Change the display of the P4 operand of CursorHint in EXPLAIN output to function notation. (check-in: bee73d429c user: drh tags: cursor-hints) | |
Changes
Changes to src/wherecode.c.
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665 666 667 668 669 670 671 | return rc; } /* ** Insert an OP_CursorHint instruction if it is appropriate to do so. */ static void codeCursorHint( | | | > > | > > > > > > > > > > > > > > > | | 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 | return rc; } /* ** Insert an OP_CursorHint instruction if it is appropriate to do so. */ static void codeCursorHint( WhereInfo *pWInfo, /* The where clause */ WhereLevel *pLevel, /* Which loop to provide hints for */ WhereTerm *pEndRange /* Hint this end-of-scan boundary term if not NULL */ ){ Parse *pParse = pWInfo->pParse; sqlite3 *db = pParse->db; Vdbe *v = pParse->pVdbe; Expr *pExpr = 0; WhereLoop *pLoop = pLevel->pWLoop; int iCur; WhereClause *pWC; WhereTerm *pTerm; WhereLoop *pWLoop; int i, j; struct CCurHint sHint; Walker sWalker; if( OptimizationDisabled(db, SQLITE_CursorHints) ) return; iCur = pLevel->iTabCur; assert( iCur==pWInfo->pTabList->a[pLevel->iFrom].iCursor ); sHint.iTabCur = iCur; sHint.iIdxCur = pLevel->iIdxCur; sHint.pIdx = pLoop->u.btree.pIndex; memset(&sWalker, 0, sizeof(sWalker)); sWalker.pParse = pParse; sWalker.u.pCCurHint = &sHint; pWC = &pWInfo->sWC; pWLoop = pLevel->pWLoop; for(i=0; i<pWC->nTerm; i++){ pTerm = &pWC->a[i]; if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue; if( pTerm->prereqAll & pLevel->notReady ) continue; if( ExprHasProperty(pTerm->pExpr, EP_FromJoin) ) continue; /* All terms in pWLoop->aLTerm[] except pEndRange are used to initialize ** the cursor. No need to hint initialization terms. */ if( pTerm!=pEndRange ){ for(j=0; j<pWLoop->nLTerm && pWLoop->aLTerm[j]!=pTerm; j++){} if( j<pWLoop->nLTerm ) continue; } /* No subqueries or non-deterministic functions allowed */ if( sqlite3ExprContainsSubquery(pTerm->pExpr) ) continue; /* For an index scan, make sure referenced columns are actually in ** the index. */ if( sHint.pIdx!=0 ){ sWalker.eCode = 0; sWalker.xExprCallback = codeCursorHintCheckExpr; sqlite3WalkExpr(&sWalker, pTerm->pExpr); if( sWalker.eCode ) continue; } /* If we survive all prior tests, that means this term is worth hinting */ pExpr = sqlite3ExprAnd(db, pExpr, sqlite3ExprDup(db, pTerm->pExpr, 0)); } if( pExpr!=0 ){ sWalker.xExprCallback = codeCursorHintFixExpr; sqlite3WalkExpr(&sWalker, pExpr); sqlite3VdbeAddOp4(v, OP_CursorHint, (sHint.pIdx ? sHint.iIdxCur : sHint.iTabCur), 0, 0, (const char*)pExpr, P4_EXPR); } } #else # define codeCursorHint(A,B,C) /* No-op */ #endif /* SQLITE_ENABLE_CURSOR_HINTS */ /* ** Generate code for the start of the iLevel-th loop in the WHERE clause ** implementation described by pWInfo. */ Bitmask sqlite3WhereCodeOneLoopStart( |
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879 880 881 882 883 884 885 | if( pLoop->wsFlags & WHERE_TOP_LIMIT ) pEnd = pLoop->aLTerm[j++]; assert( pStart!=0 || pEnd!=0 ); if( bRev ){ pTerm = pStart; pStart = pEnd; pEnd = pTerm; } | | | 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 | if( pLoop->wsFlags & WHERE_TOP_LIMIT ) pEnd = pLoop->aLTerm[j++]; assert( pStart!=0 || pEnd!=0 ); if( bRev ){ pTerm = pStart; pStart = pEnd; pEnd = pTerm; } codeCursorHint(pWInfo, pLevel, pEnd); if( pStart ){ Expr *pX; /* The expression that defines the start bound */ int r1, rTemp; /* Registers for holding the start boundary */ /* The following constant maps TK_xx codes into corresponding ** seek opcodes. It depends on a particular ordering of TK_xx */ |
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1102 1103 1104 1105 1106 1107 1108 | testcase( pRangeEnd && (pRangeEnd->eOperator & WO_LE)!=0 ); testcase( pRangeEnd && (pRangeEnd->eOperator & WO_GE)!=0 ); startEq = !pRangeStart || pRangeStart->eOperator & (WO_LE|WO_GE); endEq = !pRangeEnd || pRangeEnd->eOperator & (WO_LE|WO_GE); start_constraints = pRangeStart || nEq>0; /* Seek the index cursor to the start of the range. */ | | | 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 | testcase( pRangeEnd && (pRangeEnd->eOperator & WO_LE)!=0 ); testcase( pRangeEnd && (pRangeEnd->eOperator & WO_GE)!=0 ); startEq = !pRangeStart || pRangeStart->eOperator & (WO_LE|WO_GE); endEq = !pRangeEnd || pRangeEnd->eOperator & (WO_LE|WO_GE); start_constraints = pRangeStart || nEq>0; /* Seek the index cursor to the start of the range. */ codeCursorHint(pWInfo, pLevel, pRangeEnd); nConstraint = nEq; if( pRangeStart ){ Expr *pRight = pRangeStart->pExpr->pRight; sqlite3ExprCode(pParse, pRight, regBase+nEq); whereLikeOptimizationStringFixup(v, pLevel, pRangeStart); if( (pRangeStart->wtFlags & TERM_VNULL)==0 && sqlite3ExprCanBeNull(pRight) |
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1530 1531 1532 1533 1534 1535 1536 | static const u8 aStart[] = { OP_Rewind, OP_Last }; assert( bRev==0 || bRev==1 ); if( pTabItem->isRecursive ){ /* Tables marked isRecursive have only a single row that is stored in ** a pseudo-cursor. No need to Rewind or Next such cursors. */ pLevel->op = OP_Noop; }else{ | | | 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 | static const u8 aStart[] = { OP_Rewind, OP_Last }; assert( bRev==0 || bRev==1 ); if( pTabItem->isRecursive ){ /* Tables marked isRecursive have only a single row that is stored in ** a pseudo-cursor. No need to Rewind or Next such cursors. */ pLevel->op = OP_Noop; }else{ codeCursorHint(pWInfo, pLevel, 0); pLevel->op = aStep[bRev]; pLevel->p1 = iCur; pLevel->p2 = 1 + sqlite3VdbeAddOp2(v, aStart[bRev], iCur, addrBrk); VdbeCoverageIf(v, bRev==0); VdbeCoverageIf(v, bRev!=0); pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP; } |
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Changes to test/cursorhint.test.
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90 91 92 93 94 95 96 | p4_of_opcode db CursorHint { SELECT * FROM t3 WHERE a<15 AND b>22 AND id!=98 } } {AND(AND(LT(c1,15),GT(c2,22)),NE(c0,98))} # Indexed queries # | | | > > > > > | | | > > > > > | > > > > > > > > > > > > > > > > > > > > | 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 | p4_of_opcode db CursorHint { SELECT * FROM t3 WHERE a<15 AND b>22 AND id!=98 } } {AND(AND(LT(c1,15),GT(c2,22)),NE(c0,98))} # Indexed queries # do_test 4.1asc { db eval { CREATE INDEX t1bc ON t1(b,c); CREATE INDEX t2yz ON t2(y,z); } p4_of_opcode db CursorHint { SELECT * FROM t1 WHERE b>11 ORDER BY b ASC; } } {} do_test 4.1desc { p4_of_opcode db CursorHint { SELECT * FROM t1 WHERE b>11 ORDER BY b DESC; } } {GT(c0,11)} do_test 4.2 { p5_of_opcode db OpenRead . { SELECT * FROM t1 WHERE b>11; } } {02 00} do_test 4.3asc { p4_of_opcode db CursorHint { SELECT c FROM t1 WHERE b<11 ORDER BY b ASC; } } {LT(c0,11)} do_test 4.3desc { p4_of_opcode db CursorHint { SELECT c FROM t1 WHERE b<11 ORDER BY b DESC; } } {} do_test 4.4 { p5_of_opcode db OpenRead . { SELECT c FROM t1 WHERE b<11; } } {00} do_test 4.5asc { p4_of_opcode db CursorHint { SELECT c FROM t1 WHERE b>=10 AND b<=20 ORDER BY b ASC; } } {LE(c0,20)} do_test 4.5desc { p4_of_opcode db CursorHint { SELECT c FROM t1 WHERE b>=10 AND b<=20 ORDER BY b DESC; } } {GE(c0,10)} do_test 4.6asc { p4_of_opcode db CursorHint { SELECT rowid FROM t1 WHERE b=22 AND c>=10 AND c<=20 ORDER BY b,c ASC; } } {LE(c1,20)} do_test 4.6desc { p4_of_opcode db CursorHint { SELECT rowid FROM t1 WHERE b=22 AND c>=10 AND c<=20 ORDER BY b,c DESC; } } {GE(c1,10)} finish_test |