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Overview
Comment: | Avoid unnecessary moving of content between registers during an ORDER BY. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | orderby-planning |
Files: | files | file ages | folders |
SHA1: |
4f472accf072d9cb64f209923924b26f |
User & Date: | drh 2014-03-24 18:08:15.960 |
Context
2014-03-24
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20:19 | Omit the sequence value from sorter records used by GROUP BY queries that cannot use an index. (check-in: 3f90abddc3 user: dan tags: orderby-planning) | |
18:08 | Avoid unnecessary moving of content between registers during an ORDER BY. (check-in: 4f472accf0 user: drh tags: orderby-planning) | |
09:34 | Remove an unnecessary temporary register allocation. (check-in: 5d506743f5 user: dan tags: orderby-planning) | |
Changes
Changes to src/select.c.
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459 460 461 462 463 464 465 | ** through regData+nData-1 onto the sorter. */ static void pushOntoSorter( Parse *pParse, /* Parser context */ SortCtx *pSort, /* Information about the ORDER BY clause */ Select *pSelect, /* The whole SELECT statement */ int regData, /* First register holding data to be sorted */ | | > | > > > > > > > | > | 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 | ** through regData+nData-1 onto the sorter. */ static void pushOntoSorter( Parse *pParse, /* Parser context */ SortCtx *pSort, /* Information about the ORDER BY clause */ Select *pSelect, /* The whole SELECT statement */ int regData, /* First register holding data to be sorted */ int nData, /* Number of elements in the data array */ int nPrefixReg /* No. of reg prior to regData available for use */ ){ Vdbe *v = pParse->pVdbe; /* Stmt under construction */ int nExpr = pSort->pOrderBy->nExpr; /* No. of ORDER BY terms */ int nBase = nExpr + 1 + nData; /* Fields in sorter record */ int regBase; /* Regs for sorter record */ int regRecord = sqlite3GetTempReg(pParse); /* Assemblied sorter record */ int nOBSat = pSort->nOBSat; /* No. ORDER BY terms to skip */ int op; /* Opcode to add sorter record to sorter */ if( nPrefixReg ){ assert( nPrefixReg==nExpr+1 ); regBase = regData - nExpr - 1; }else{ regBase = sqlite3GetTempRange(pParse, nBase); } sqlite3ExprCodeExprList(pParse, pSort->pOrderBy, regBase, SQLITE_ECEL_DUP); sqlite3VdbeAddOp2(v, OP_Sequence, pSort->iECursor, regBase+nExpr); if( nPrefixReg==0 ){ sqlite3VdbeAddOp3(v, OP_Move, regData, regBase+nExpr+1, nData); } sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase+nOBSat, nBase-nOBSat, regRecord); if( nOBSat>0 ){ int regPrevKey; /* The first nOBSat columns of the previous row */ int addrFirst; /* Address of the OP_IfNot opcode */ int addrJmp; /* Address of the OP_Jump opcode */ VdbeOp *pOp; /* Opcode that opens the sorter */ int nKey; /* Number of sorting key columns, including OP_Sequence */ |
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511 512 513 514 515 516 517 | op = OP_SorterInsert; }else{ op = OP_IdxInsert; } sqlite3VdbeAddOp2(v, op, pSort->iECursor, regRecord); if( nOBSat==0 ){ sqlite3ReleaseTempReg(pParse, regRecord); | > | > | 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 | op = OP_SorterInsert; }else{ op = OP_IdxInsert; } sqlite3VdbeAddOp2(v, op, pSort->iECursor, regRecord); if( nOBSat==0 ){ sqlite3ReleaseTempReg(pParse, regRecord); if( nPrefixReg==0 ){ sqlite3ReleaseTempRange(pParse, regBase, nBase); } } if( pSelect->iLimit ){ int addr1, addr2; int iLimit; if( pSelect->iOffset ){ iLimit = pSelect->iOffset+1; }else{ |
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627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 | Vdbe *v = pParse->pVdbe; int i; int hasDistinct; /* True if the DISTINCT keyword is present */ int regResult; /* Start of memory holding result set */ int eDest = pDest->eDest; /* How to dispose of results */ int iParm = pDest->iSDParm; /* First argument to disposal method */ int nResultCol; /* Number of result columns */ assert( v ); assert( pEList!=0 ); hasDistinct = pDistinct ? pDistinct->eTnctType : WHERE_DISTINCT_NOOP; if( pSort && pSort->pOrderBy==0 ) pSort = 0; if( pSort==0 && !hasDistinct ){ assert( iContinue!=0 ); codeOffset(v, p->iOffset, iContinue); } /* Pull the requested columns. */ nResultCol = pEList->nExpr; if( pDest->iSdst==0 ){ pDest->iSdst = pParse->nMem+1; pParse->nMem += nResultCol; }else if( pDest->iSdst+nResultCol > pParse->nMem ){ /* This is an error condition that can result, for example, when a SELECT ** on the right-hand side of an INSERT contains more result columns than ** there are columns in the table on the left. The error will be caught ** and reported later. But we need to make sure enough memory is allocated | > > > > > | 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 | Vdbe *v = pParse->pVdbe; int i; int hasDistinct; /* True if the DISTINCT keyword is present */ int regResult; /* Start of memory holding result set */ int eDest = pDest->eDest; /* How to dispose of results */ int iParm = pDest->iSDParm; /* First argument to disposal method */ int nResultCol; /* Number of result columns */ int nPrefixReg = 0; /* Number of extra registers before regResult */ assert( v ); assert( pEList!=0 ); hasDistinct = pDistinct ? pDistinct->eTnctType : WHERE_DISTINCT_NOOP; if( pSort && pSort->pOrderBy==0 ) pSort = 0; if( pSort==0 && !hasDistinct ){ assert( iContinue!=0 ); codeOffset(v, p->iOffset, iContinue); } /* Pull the requested columns. */ nResultCol = pEList->nExpr; if( pDest->iSdst==0 ){ if( pSort ){ nPrefixReg = pSort->pOrderBy->nExpr + 1; pParse->nMem += nPrefixReg; } pDest->iSdst = pParse->nMem+1; pParse->nMem += nResultCol; }else if( pDest->iSdst+nResultCol > pParse->nMem ){ /* This is an error condition that can result, for example, when a SELECT ** on the right-hand side of an INSERT contains more result columns than ** there are columns in the table on the left. The error will be caught ** and reported later. But we need to make sure enough memory is allocated |
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758 759 760 761 762 763 764 | /* Store the result as data using a unique key. */ case SRT_Fifo: case SRT_DistFifo: case SRT_Table: case SRT_EphemTab: { | | | | | | | 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 | /* Store the result as data using a unique key. */ case SRT_Fifo: case SRT_DistFifo: case SRT_Table: case SRT_EphemTab: { int r1 = sqlite3GetTempRange(pParse, nPrefixReg+1); testcase( eDest==SRT_Table ); testcase( eDest==SRT_EphemTab ); sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1+nPrefixReg); #ifndef SQLITE_OMIT_CTE if( eDest==SRT_DistFifo ){ /* If the destination is DistFifo, then cursor (iParm+1) is open ** on an ephemeral index. If the current row is already present ** in the index, do not write it to the output. If not, add the ** current row to the index and proceed with writing it to the ** output table as well. */ int addr = sqlite3VdbeCurrentAddr(v) + 4; sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, addr, r1, 0); VdbeCoverage(v); sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm+1, r1); assert( pSort==0 ); } #endif if( pSort ){ pushOntoSorter(pParse, pSort, p, r1+nPrefixReg, 1, nPrefixReg); }else{ int r2 = sqlite3GetTempReg(pParse); sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, r2); sqlite3VdbeAddOp3(v, OP_Insert, iParm, r1, r2); sqlite3VdbeChangeP5(v, OPFLAG_APPEND); sqlite3ReleaseTempReg(pParse, r2); } sqlite3ReleaseTempRange(pParse, r1, nPrefixReg+1); break; } #ifndef SQLITE_OMIT_SUBQUERY /* If we are creating a set for an "expr IN (SELECT ...)" construct, ** then there should be a single item on the stack. Write this ** item into the set table with bogus data. */ case SRT_Set: { assert( nResultCol==1 ); pDest->affSdst = sqlite3CompareAffinity(pEList->a[0].pExpr, pDest->affSdst); if( pSort ){ /* At first glance you would think we could optimize out the ** ORDER BY in this case since the order of entries in the set ** does not matter. But there might be a LIMIT clause, in which ** case the order does matter */ pushOntoSorter(pParse, pSort, p, regResult, 1, nPrefixReg); }else{ int r1 = sqlite3GetTempReg(pParse); sqlite3VdbeAddOp4(v, OP_MakeRecord, regResult,1,r1, &pDest->affSdst, 1); sqlite3ExprCacheAffinityChange(pParse, regResult, 1); sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1); sqlite3ReleaseTempReg(pParse, r1); } |
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828 829 830 831 832 833 834 | /* If this is a scalar select that is part of an expression, then ** store the results in the appropriate memory cell and break out ** of the scan loop. */ case SRT_Mem: { assert( nResultCol==1 ); if( pSort ){ | | | | 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 | /* If this is a scalar select that is part of an expression, then ** store the results in the appropriate memory cell and break out ** of the scan loop. */ case SRT_Mem: { assert( nResultCol==1 ); if( pSort ){ pushOntoSorter(pParse, pSort, p, regResult, 1, nPrefixReg); }else{ sqlite3ExprCodeMove(pParse, regResult, iParm, 1); /* The LIMIT clause will jump out of the loop for us */ } break; } #endif /* #ifndef SQLITE_OMIT_SUBQUERY */ case SRT_Coroutine: /* Send data to a co-routine */ case SRT_Output: { /* Return the results */ testcase( eDest==SRT_Coroutine ); testcase( eDest==SRT_Output ); if( pSort ){ pushOntoSorter(pParse, pSort, p, regResult, nResultCol, nPrefixReg); }else if( eDest==SRT_Coroutine ){ sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm); }else{ sqlite3VdbeAddOp2(v, OP_ResultRow, regResult, nResultCol); sqlite3ExprCacheAffinityChange(pParse, regResult, nResultCol); } break; |
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