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Overview
Comment: | Scan the table backwards if there is an ORDER BY ... DESC clause that can be satisfied by an index. (CVS 795) |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
c7a3487981de0ed5b43ea3ff4d46ab44 |
User & Date: | drh 2002-12-04 20:01:06.000 |
Context
2002-12-04
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21:50 | Fixes to the logic that decides if the ORDER BY can be ignored due to the use of an index. Tests updated. (CVS 796) (check-in: bfb9a2aa93 user: drh tags: trunk) | |
20:01 | Scan the table backwards if there is an ORDER BY ... DESC clause that can be satisfied by an index. (CVS 795) (check-in: c7a3487981 user: drh tags: trunk) | |
13:40 | Add the sqliteBtreePrevious() routine to the BTree module API. This is in anticipation of implementing reverse order searching of a table. (CVS 794) (check-in: 0ad1d93879 user: drh tags: trunk) | |
Changes
Changes to src/sqliteInt.h.
1 2 3 4 5 6 7 8 9 10 11 12 13 | /* ** 2001 September 15 ** ** The author disclaims copyright to this source code. In place of ** a legal notice, here is a blessing: ** ** May you do good and not evil. ** May you find forgiveness for yourself and forgive others. ** May you share freely, never taking more than you give. ** ************************************************************************* ** Internal interface definitions for SQLite. ** | | | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | /* ** 2001 September 15 ** ** The author disclaims copyright to this source code. In place of ** a legal notice, here is a blessing: ** ** May you do good and not evil. ** May you find forgiveness for yourself and forgive others. ** May you share freely, never taking more than you give. ** ************************************************************************* ** Internal interface definitions for SQLite. ** ** @(#) $Id: sqliteInt.h,v 1.150 2002/12/04 20:01:06 drh Exp $ */ #include "config.h" #include "sqlite.h" #include "hash.h" #include "vdbe.h" #include "parse.h" #include "btree.h" |
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610 611 612 613 614 615 616 617 618 619 620 621 622 623 | int score; /* How well this indexed scored */ int brk; /* Jump here to break out of the loop */ int cont; /* Jump here to continue with the next loop cycle */ int op, p1, p2; /* Opcode used to terminate the loop */ int iLeftJoin; /* Memory cell used to implement LEFT OUTER JOIN */ int top; /* First instruction of interior of the loop */ int inOp, inP1, inP2;/* Opcode used to implement an IN operator */ }; /* ** The WHERE clause processing routine has two halves. The ** first part does the start of the WHERE loop and the second ** half does the tail of the WHERE loop. An instance of ** this structure is returned by the first half and passed | > | 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 | int score; /* How well this indexed scored */ int brk; /* Jump here to break out of the loop */ int cont; /* Jump here to continue with the next loop cycle */ int op, p1, p2; /* Opcode used to terminate the loop */ int iLeftJoin; /* Memory cell used to implement LEFT OUTER JOIN */ int top; /* First instruction of interior of the loop */ int inOp, inP1, inP2;/* Opcode used to implement an IN operator */ int bRev; /* Do the scan in the reverse direction */ }; /* ** The WHERE clause processing routine has two halves. The ** first part does the start of the WHERE loop and the second ** half does the tail of the WHERE loop. An instance of ** this structure is returned by the first half and passed |
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Changes to src/vdbe.c.
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32 33 34 35 36 37 38 | ** ** Various scripts scan this source file in order to generate HTML ** documentation, headers files, or other derived files. The formatting ** of the code in this file is, therefore, important. See other comments ** in this file for details. If in doubt, do not deviate from existing ** commenting and indentation practices when changing or adding code. ** | | | 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 | ** ** Various scripts scan this source file in order to generate HTML ** documentation, headers files, or other derived files. The formatting ** of the code in this file is, therefore, important. See other comments ** in this file for details. If in doubt, do not deviate from existing ** commenting and indentation practices when changing or adding code. ** ** $Id: vdbe.c,v 1.186 2002/12/04 20:01:06 drh Exp $ */ #include "sqliteInt.h" #include <ctype.h> /* ** The makefile scans this source file and creates the following ** array of string constants which are the names of all VDBE opcodes. |
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3350 3351 3352 3353 3354 3355 3356 | ** Pop the top of the stack and use its value as a key. Reposition ** cursor P1 so that it points to an entry with a matching key. If ** the table contains no record with a matching key, then the cursor ** is left pointing at the first record that is greater than the key. ** If there are no records greater than the key and P2 is not zero, ** then an immediate jump to P2 is made. ** | | > > > > > > > > > > > | > | > > > > > > | 3350 3351 3352 3353 3354 3355 3356 3357 3358 3359 3360 3361 3362 3363 3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374 3375 3376 3377 3378 3379 3380 3381 3382 3383 3384 3385 3386 3387 3388 3389 3390 3391 3392 3393 3394 3395 3396 3397 3398 3399 3400 3401 3402 3403 3404 3405 3406 3407 3408 | ** Pop the top of the stack and use its value as a key. Reposition ** cursor P1 so that it points to an entry with a matching key. If ** the table contains no record with a matching key, then the cursor ** is left pointing at the first record that is greater than the key. ** If there are no records greater than the key and P2 is not zero, ** then an immediate jump to P2 is made. ** ** See also: Found, NotFound, Distinct, MoveLt */ /* Opcode: MoveLt P1 P2 * ** ** Pop the top of the stack and use its value as a key. Reposition ** cursor P1 so that it points to the entry with the largest key that is ** less than the key popped from the stack. ** If there are no records less than than the key and P2 ** is not zero then an immediate jump to P2 is made. ** ** See also: MoveTo */ case OP_MoveLt: case OP_MoveTo: { int i = pOp->p1; int tos = p->tos; Cursor *pC; VERIFY( if( tos<0 ) goto not_enough_stack; ) if( i>=0 && i<p->nCursor && (pC = &p->aCsr[i])->pCursor!=0 ){ int res, oc; if( aStack[tos].flags & STK_Int ){ int iKey = intToKey(aStack[tos].i); sqliteBtreeMoveto(pC->pCursor, (char*)&iKey, sizeof(int), &res); pC->lastRecno = aStack[tos].i; pC->recnoIsValid = res==0; }else{ if( Stringify(p, tos) ) goto no_mem; sqliteBtreeMoveto(pC->pCursor, zStack[tos], aStack[tos].n, &res); pC->recnoIsValid = 0; } pC->nullRow = 0; sqlite_search_count++; oc = pOp->opcode; if( oc==OP_MoveTo && res<0 ){ sqliteBtreeNext(pC->pCursor, &res); pC->recnoIsValid = 0; if( res && pOp->p2>0 ){ pc = pOp->p2 - 1; } }else if( oc==OP_MoveLt && res>=0 ){ sqliteBtreePrevious(pC->pCursor, &res); pC->recnoIsValid = 0; if( res && pOp->p2>0 ){ pc = pOp->p2 - 1; } } } POPSTACK; break; } |
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4022 4023 4024 4025 4026 4027 4028 4029 4030 4031 4032 4033 4034 4035 4036 4037 4038 | /* Opcode: Next P1 P2 * ** ** Advance cursor P1 so that it points to the next key/data pair in its ** table or index. If there are no more key/value pairs then fall through ** to the following instruction. But if the cursor advance was successful, ** jump immediately to P2. */ case OP_Next: { int i = pOp->p1; BtCursor *pCrsr; if( VERIFY( i>=0 && i<p->nCursor && ) (pCrsr = p->aCsr[i].pCursor)!=0 ){ int res; if( p->aCsr[i].nullRow ){ res = 1; }else{ | > > > > > > > > > > | > | 4040 4041 4042 4043 4044 4045 4046 4047 4048 4049 4050 4051 4052 4053 4054 4055 4056 4057 4058 4059 4060 4061 4062 4063 4064 4065 4066 4067 4068 4069 4070 4071 4072 4073 4074 4075 | /* Opcode: Next P1 P2 * ** ** Advance cursor P1 so that it points to the next key/data pair in its ** table or index. If there are no more key/value pairs then fall through ** to the following instruction. But if the cursor advance was successful, ** jump immediately to P2. ** ** See also: Prev */ /* Opcode: Prev P1 P2 * ** ** Back up cursor P1 so that it points to the previous key/data pair in its ** table or index. If there is no previous key/value pairs then fall through ** to the following instruction. But if the cursor backup was successful, ** jump immediately to P2. */ case OP_Prev: case OP_Next: { int i = pOp->p1; BtCursor *pCrsr; if( VERIFY( i>=0 && i<p->nCursor && ) (pCrsr = p->aCsr[i].pCursor)!=0 ){ int res; if( p->aCsr[i].nullRow ){ res = 1; }else{ rc = pOp->opcode==OP_Next ? sqliteBtreeNext(pCrsr, &res) : sqliteBtreePrevious(pCrsr, &res); p->aCsr[i].nullRow = res; } if( res==0 ){ pc = pOp->p2 - 1; sqlite_search_count++; } p->aCsr[i].recnoIsValid = 0; |
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4160 4161 4162 4163 4164 4165 4166 4167 4168 4169 4170 4171 4172 4173 4174 4175 4176 4177 4178 4179 4180 | ** Compare the top of the stack against the key on the index entry that ** cursor P1 is currently pointing to. Ignore the last 4 bytes of the ** index entry. If the index entry is greater than or equal to ** the top of the stack ** then jump to P2. Otherwise fall through to the next instruction. ** In either case, the stack is popped once. */ case OP_IdxGT: case OP_IdxGE: { int i= pOp->p1; int tos = p->tos; BtCursor *pCrsr; if( VERIFY( i>=0 && i<p->nCursor && ) (pCrsr = p->aCsr[i].pCursor)!=0 ){ int res, rc; if( Stringify(p, tos) ) goto no_mem; rc = sqliteBtreeKeyCompare(pCrsr, zStack[tos], aStack[tos].n, 4, &res); if( rc!=SQLITE_OK ){ break; } | > > > > > > > > > | > > | 4189 4190 4191 4192 4193 4194 4195 4196 4197 4198 4199 4200 4201 4202 4203 4204 4205 4206 4207 4208 4209 4210 4211 4212 4213 4214 4215 4216 4217 4218 4219 4220 4221 4222 4223 4224 4225 4226 4227 4228 | ** Compare the top of the stack against the key on the index entry that ** cursor P1 is currently pointing to. Ignore the last 4 bytes of the ** index entry. If the index entry is greater than or equal to ** the top of the stack ** then jump to P2. Otherwise fall through to the next instruction. ** In either case, the stack is popped once. */ /* Opcode: IdxLT P1 P2 * ** ** Compare the top of the stack against the key on the index entry that ** cursor P1 is currently pointing to. Ignore the last 4 bytes of the ** index entry. If the index entry is less than the top of the stack ** then jump to P2. Otherwise fall through to the next instruction. ** In either case, the stack is popped once. */ case OP_IdxLT: case OP_IdxGT: case OP_IdxGE: { int i= pOp->p1; int tos = p->tos; BtCursor *pCrsr; if( VERIFY( i>=0 && i<p->nCursor && ) (pCrsr = p->aCsr[i].pCursor)!=0 ){ int res, rc; if( Stringify(p, tos) ) goto no_mem; rc = sqliteBtreeKeyCompare(pCrsr, zStack[tos], aStack[tos].n, 4, &res); if( rc!=SQLITE_OK ){ break; } if( pOp->opcode==OP_IdxLT ){ res = -res; }else if( pOp->opcode==OP_IdxGE ){ res++; } if( res>0 ){ pc = pOp->p2 - 1 ; } } POPSTACK; |
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Changes to src/where.c.
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9 10 11 12 13 14 15 | ** May you share freely, never taking more than you give. ** ************************************************************************* ** This module contains C code that generates VDBE code used to process ** the WHERE clause of SQL statements. Also found here are subroutines ** to generate VDBE code to evaluate expressions. ** | | | 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | ** May you share freely, never taking more than you give. ** ************************************************************************* ** This module contains C code that generates VDBE code used to process ** the WHERE clause of SQL statements. Also found here are subroutines ** to generate VDBE code to evaluate expressions. ** ** $Id: where.c,v 1.68 2002/12/04 20:01:06 drh Exp $ */ #include "sqliteInt.h" /* ** The query generator uses an array of instances of this structure to ** help it analyze the subexpressions of the WHERE clause. Each WHERE ** clause subexpression is separated from the others by an AND operator. |
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165 166 167 168 169 170 171 | ** If there are two or more indices that generate the correct sort order ** and pPreferredIdx is one of those indices, then return pPreferredIdx. */ static Index *findSortingIndex( Table *pTab, /* The table to be sorted */ int base, /* Cursor number for pTab */ ExprList *pOrderBy, /* The ORDER BY clause */ | | > > > | | > | > > > | 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 | ** If there are two or more indices that generate the correct sort order ** and pPreferredIdx is one of those indices, then return pPreferredIdx. */ static Index *findSortingIndex( Table *pTab, /* The table to be sorted */ int base, /* Cursor number for pTab */ ExprList *pOrderBy, /* The ORDER BY clause */ Index *pPreferredIdx, /* Use this index, if possible and not NULL */ int *pbRev /* Set to 1 if ORDER BY is DESC */ ){ int i; Index *pMatch; Index *pIdx; int sortOrder; assert( pOrderBy!=0 ); assert( pOrderBy->nExpr>0 ); sortOrder = pOrderBy->a[0].sortOrder & SQLITE_SO_DIRMASK; for(i=0; i<pOrderBy->nExpr; i++){ Expr *p; if( (pOrderBy->a[i].sortOrder & SQLITE_SO_DIRMASK)!=sortOrder ){ /* Indices can only be used if all ORDER BY terms are either ** DESC or ASC. Indices cannot be used on a mixture. */ return 0; } if( (pOrderBy->a[i].sortOrder & SQLITE_SO_TYPEMASK)!=SQLITE_SO_UNK ){ /* Do not sort by index if there is a COLLATE clause */ return 0; } p = pOrderBy->a[i].pExpr; if( p->op!=TK_COLUMN || p->iTable!=base ){ /* Can not use an index sort on anything that is not a column in the ** left-most table of the FROM clause */ return 0; } } /* If we get this far, it means the ORDER BY clause consists only of ** ascending columns in the left-most table of the FROM clause. Now ** check for a matching index. */ pMatch = 0; for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ if( pIdx->nColumn<pOrderBy->nExpr ) continue; for(i=0; i<pOrderBy->nExpr; i++){ if( pOrderBy->a[i].pExpr->iColumn!=pIdx->aiColumn[i] ) break; } if( i>=pOrderBy->nExpr ){ pMatch = pIdx; if( pIdx==pPreferredIdx ) break; } } if( pMatch && pbRev ){ *pbRev = sortOrder==SQLITE_SO_DESC; } return pMatch; } /* ** Generate the beginning of the loop used for WHERE clause processing. ** The return value is a pointer to an (opaque) structure that contains ** information needed to terminate the loop. Later, the calling routine |
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464 465 466 467 468 469 470 | /* Do a search for usable indices. Leave pBestIdx pointing to ** the "best" index. pBestIdx is left set to NULL if no indices ** are usable. ** ** The best index is determined as follows. For each of the ** left-most terms that is fixed by an equality operator, add | | | | > | 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 | /* Do a search for usable indices. Leave pBestIdx pointing to ** the "best" index. pBestIdx is left set to NULL if no indices ** are usable. ** ** The best index is determined as follows. For each of the ** left-most terms that is fixed by an equality operator, add ** 8 to the score. The right-most term of the index may be ** constrained by an inequality. Add 1 if for an "x<..." constraint ** and add 2 for an "x>..." constraint. Chose the index that ** gives the best score. ** ** This scoring system is designed so that the score can later be ** used to determine how the index is used. If the score&7 is 0 ** then all constraints are equalities. If score&1 is not 0 then ** there is an inequality used as a termination key. (ex: "x<...") ** If score&2 is not 0 then there is an inequality used as the ** start key. (ex: "x>..."). A score or 4 is the special case ** of an IN operator constraint. (ex: "x IN ..."). ** ** The IN operator (as in "<expr> IN (...)") is treated the same as ** an equality comparison except that it can only be used on the ** left-most column of an index and other terms of the WHERE clause ** cannot be used in conjunction with the IN operator to help satisfy ** other columns of the index. */ |
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558 559 560 561 562 563 564 565 566 567 568 | } } break; } } } } for(nEq=0; nEq<pIdx->nColumn; nEq++){ m = (1<<(nEq+1))-1; if( (m & eqMask)!=m ) break; } | > > > > | | | | > > | < < | | | > | 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 | } } break; } } } } /* The following loop ends with nEq set to the number of columns ** on the left of the index with == constraints. */ for(nEq=0; nEq<pIdx->nColumn; nEq++){ m = (1<<(nEq+1))-1; if( (m & eqMask)!=m ) break; } score = nEq*8; /* Base score is 8 times number of == constraints */ m = 1<<nEq; if( m & ltMask ) score++; /* Increase score for a < constraint */ if( m & gtMask ) score+=2; /* Increase score for a > constraint */ if( score==0 && inMask ) score = 4; /* Default score for IN constraint */ if( score>bestScore ){ pBestIdx = pIdx; bestScore = score; } } pWInfo->a[i].pIdx = pBestIdx; pWInfo->a[i].score = bestScore; pWInfo->a[i].bRev = 0; loopMask |= 1<<idx; if( pBestIdx ){ pWInfo->a[i].iCur = pParse->nTab++; pWInfo->peakNTab = pParse->nTab; } } /* Check to see if the ORDER BY clause is or can be satisfied by the ** use of an index on the first table. */ if( ppOrderBy && *ppOrderBy && pTabList->nSrc>0 ){ Index *pSortIdx; Index *pIdx; Table *pTab; int bRev = 0; pTab = pTabList->a[0].pTab; pIdx = pWInfo->a[0].pIdx; if( pIdx && pWInfo->a[0].score==4 ){ /* If there is already an IN index on the left-most table, ** it will not give the correct sort order. ** So, pretend that no suitable index is found. */ pSortIdx = 0; }else if( iDirectEq[0]>=0 || iDirectLt[0]>=0 || iDirectGt[0]>=0 ){ /* If the left-most column is accessed using its ROWID, then do ** not try to sort by index. */ pSortIdx = 0; }else{ pSortIdx = findSortingIndex(pTab, base, *ppOrderBy, pIdx, &bRev); } if( pSortIdx && (pIdx==0 || pIdx==pSortIdx) ){ if( pIdx==0 ){ pWInfo->a[0].pIdx = pSortIdx; pWInfo->a[0].iCur = pParse->nTab++; pWInfo->peakNTab = pParse->nTab; } pWInfo->a[0].bRev = bRev; *ppOrderBy = 0; } } /* Open all tables in the pTabList and all indices used by those tables. */ for(i=0; i<pTabList->nSrc; i++){ |
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704 705 706 707 708 709 710 | pLevel->op = OP_Noop; }else if( pIdx!=0 && pLevel->score>0 && pLevel->score%4==0 ){ /* Case 2: There is an index and all terms of the WHERE clause that ** refer to the index use the "==" or "IN" operators. */ int start; int testOp; | | | 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 | pLevel->op = OP_Noop; }else if( pIdx!=0 && pLevel->score>0 && pLevel->score%4==0 ){ /* Case 2: There is an index and all terms of the WHERE clause that ** refer to the index use the "==" or "IN" operators. */ int start; int testOp; int nColumn = (pLevel->score+4)/8; brk = pLevel->brk = sqliteVdbeMakeLabel(v); for(j=0; j<nColumn; j++){ for(k=0; k<nExpr; k++){ Expr *pX = aExpr[k].p; if( pX==0 ) continue; if( aExpr[k].idxLeft==idx && (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight |
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752 753 754 755 756 757 758 | } } } pLevel->iMem = pParse->nMem++; cont = pLevel->cont = sqliteVdbeMakeLabel(v); sqliteVdbeAddOp(v, OP_MakeKey, nColumn, 0); sqliteAddIdxKeyType(v, pIdx); | | > > > > > > > > > > | | | | > > < | 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 | } } } pLevel->iMem = pParse->nMem++; cont = pLevel->cont = sqliteVdbeMakeLabel(v); sqliteVdbeAddOp(v, OP_MakeKey, nColumn, 0); sqliteAddIdxKeyType(v, pIdx); if( nColumn==pIdx->nColumn || pLevel->bRev ){ sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 0); testOp = OP_IdxGT; }else{ sqliteVdbeAddOp(v, OP_Dup, 0, 0); sqliteVdbeAddOp(v, OP_IncrKey, 0, 0); sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1); testOp = OP_IdxGE; } if( pLevel->bRev ){ /* Scan in reverse order */ sqliteVdbeAddOp(v, OP_IncrKey, 0, 0); sqliteVdbeAddOp(v, OP_MoveLt, pLevel->iCur, brk); start = sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0); sqliteVdbeAddOp(v, OP_IdxLT, pLevel->iCur, brk); sqliteVdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0); pLevel->op = OP_Prev; }else{ /* Scan in the forward order */ sqliteVdbeAddOp(v, OP_MoveTo, pLevel->iCur, brk); start = sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0); sqliteVdbeAddOp(v, testOp, pLevel->iCur, brk); sqliteVdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0); pLevel->op = OP_Next; } if( i==pTabList->nSrc-1 && pushKey ){ haveKey = 1; }else{ sqliteVdbeAddOp(v, OP_MoveTo, base+idx, 0); haveKey = 0; } pLevel->p1 = pLevel->iCur; pLevel->p2 = start; }else if( i<ARRAYSIZE(iDirectLt) && (iDirectLt[i]>=0 || iDirectGt[i]>=0) ){ /* Case 3: We have an inequality comparison against the ROWID field. */ int testOp = OP_Noop; int start; |
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858 859 860 861 862 863 864 | ** use the "==" operator. ** ** This case is also used when there are no WHERE clause ** constraints but an index is selected anyway, in order ** to force the output order to conform to an ORDER BY. */ int score = pLevel->score; | | | 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 | ** use the "==" operator. ** ** This case is also used when there are no WHERE clause ** constraints but an index is selected anyway, in order ** to force the output order to conform to an ORDER BY. */ int score = pLevel->score; int nEqColumn = score/8; int start; int leFlag, geFlag; int testOp; /* Evaluate the equality constraints */ for(j=0; j<nEqColumn; j++){ |
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896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 | /* Duplicate the equality term values because they will all be ** used twice: once to make the termination key and once to make the ** start key. */ for(j=0; j<nEqColumn; j++){ sqliteVdbeAddOp(v, OP_Dup, nEqColumn-1, 0); } /* Generate the termination key. This is the key value that ** will end the search. There is no termination key if there ** are no equality terms and no "X<..." term. */ if( (score & 1)!=0 ){ for(k=0; k<nExpr; k++){ Expr *pExpr = aExpr[k].p; if( pExpr==0 ) continue; if( aExpr[k].idxLeft==idx && (pExpr->op==TK_LT || pExpr->op==TK_LE) | > > > > > > > > | 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 | /* Duplicate the equality term values because they will all be ** used twice: once to make the termination key and once to make the ** start key. */ for(j=0; j<nEqColumn; j++){ sqliteVdbeAddOp(v, OP_Dup, nEqColumn-1, 0); } /* Labels for the beginning and end of the loop */ cont = pLevel->cont = sqliteVdbeMakeLabel(v); brk = pLevel->brk = sqliteVdbeMakeLabel(v); /* Generate the termination key. This is the key value that ** will end the search. There is no termination key if there ** are no equality terms and no "X<..." term. ** ** 2002-Dec-04: On a reverse-order scan, the so-called "termination" ** key computed here really ends up being the start key. */ if( (score & 1)!=0 ){ for(k=0; k<nExpr; k++){ Expr *pExpr = aExpr[k].p; if( pExpr==0 ) continue; if( aExpr[k].idxLeft==idx && (pExpr->op==TK_LT || pExpr->op==TK_LE) |
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938 939 940 941 942 943 944 | if( testOp!=OP_Noop ){ pLevel->iMem = pParse->nMem++; sqliteVdbeAddOp(v, OP_MakeKey, nEqColumn + (score & 1), 0); sqliteAddIdxKeyType(v, pIdx); if( leFlag ){ sqliteVdbeAddOp(v, OP_IncrKey, 0, 0); } | > > > | > > > > > > | 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 | if( testOp!=OP_Noop ){ pLevel->iMem = pParse->nMem++; sqliteVdbeAddOp(v, OP_MakeKey, nEqColumn + (score & 1), 0); sqliteAddIdxKeyType(v, pIdx); if( leFlag ){ sqliteVdbeAddOp(v, OP_IncrKey, 0, 0); } if( pLevel->bRev ){ sqliteVdbeAddOp(v, OP_MoveLt, pLevel->iCur, brk); }else{ sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1); } }else if( pLevel->bRev ){ sqliteVdbeAddOp(v, OP_Last, pLevel->iCur, brk); } /* Generate the start key. This is the key that defines the lower ** bound on the search. There is no start key if there are no ** equality terms and if there is no "X>..." term. In ** that case, generate a "Rewind" instruction in place of the ** start key search. ** ** 2002-Dec-04: In the case of a reverse-order search, the so-called ** "start" key really ends up being used as the termination key. */ if( (score & 2)!=0 ){ for(k=0; k<nExpr; k++){ Expr *pExpr = aExpr[k].p; if( pExpr==0 ) continue; if( aExpr[k].idxLeft==idx && (pExpr->op==TK_GT || pExpr->op==TK_GE) |
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975 976 977 978 979 980 981 | aExpr[k].p = 0; break; } } }else{ geFlag = 1; } | < < > > > > > | > > > | 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 | aExpr[k].p = 0; break; } } }else{ geFlag = 1; } if( nEqColumn>0 || (score&2)!=0 ){ sqliteVdbeAddOp(v, OP_MakeKey, nEqColumn + ((score&2)!=0), 0); sqliteAddIdxKeyType(v, pIdx); if( !geFlag ){ sqliteVdbeAddOp(v, OP_IncrKey, 0, 0); } if( pLevel->bRev ){ pLevel->iMem = pParse->nMem++; sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1); testOp = OP_IdxLT; }else{ sqliteVdbeAddOp(v, OP_MoveTo, pLevel->iCur, brk); } }else if( pLevel->bRev ){ testOp = OP_Noop; }else{ sqliteVdbeAddOp(v, OP_Rewind, pLevel->iCur, brk); } /* Generate the the top of the loop. If there is a termination ** key we have to test for that key and abort at the top of the ** loop. |
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1007 1008 1009 1010 1011 1012 1013 | }else{ sqliteVdbeAddOp(v, OP_MoveTo, base+idx, 0); haveKey = 0; } /* Record the instruction used to terminate the loop. */ | | | 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 | }else{ sqliteVdbeAddOp(v, OP_MoveTo, base+idx, 0); haveKey = 0; } /* Record the instruction used to terminate the loop. */ pLevel->op = pLevel->bRev ? OP_Prev : OP_Next; pLevel->p1 = pLevel->iCur; pLevel->p2 = start; } loopMask |= 1<<idx; /* Insert code to test every subexpression that can be completely ** computed using the current set of tables. |
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