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Overview
| Comment: | Remove a pointless OP_Once operation in ORDER BY clauses with LIMIT. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | orderby-planning |
| Files: | files | file ages | folders |
| SHA1: |
e6c59d23316c83b318b1a94d9b28a5d3 |
| User & Date: | drh 2014-03-24 02:20:53 |
Context
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2014-03-24
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| 09:34 | Remove an unnecessary temporary register allocation. (check-in: 5d506743 user: dan tags: orderby-planning) | |
| 02:20 | Remove a pointless OP_Once operation in ORDER BY clauses with LIMIT. (check-in: e6c59d23 user: drh tags: orderby-planning) | |
| 01:43 | Further enhancements to generated VDBE code for ORDER BY. (check-in: e7188fad user: drh tags: orderby-planning) | |
Changes
Changes to src/select.c.
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struct ExprList_item *aOutEx = p->pEList->a;
#endif
if( pSort->labelBkOut ){
sqlite3VdbeAddOp2(v, OP_Gosub, pSort->regReturn, pSort->labelBkOut);
sqlite3VdbeAddOp2(v, OP_Goto, 0, addrBreak);
sqlite3VdbeResolveLabel(v, pSort->labelBkOut);
addrOnce = sqlite3CodeOnce(pParse); VdbeCoverage(v);
}
iTab = pSort->iECursor;
regRow = sqlite3GetTempReg(pParse);
if( eDest==SRT_Output || eDest==SRT_Coroutine ){
regRowid = 0;
regRow = pDest->iSdst;
nSortData = nColumn;
................................................................................
regRow = sqlite3GetTempReg(pParse);
nSortData = 1;
}
nKey = pOrderBy->nExpr - pSort->nOBSat;
if( pSort->sortFlags & SORTFLAG_UseSorter ){
int regSortOut = ++pParse->nMem;
iSortTab = pParse->nTab++;
sqlite3VdbeAddOp3(v, OP_OpenPseudo, iSortTab, regSortOut, nKey+1+nSortData);
if( addrOnce ) sqlite3VdbeJumpHere(v, addrOnce);
addr = 1 + sqlite3VdbeAddOp2(v, OP_SorterSort, iTab, addrBreak);
VdbeCoverage(v);
codeOffset(v, p->iOffset, addrContinue);
sqlite3VdbeAddOp2(v, OP_SorterData, iTab, regSortOut);
p5 = OPFLAG_CLEARCACHE;
}else{
if( addrOnce ) sqlite3VdbeJumpHere(v, addrOnce);
addr = 1 + sqlite3VdbeAddOp2(v, OP_Sort, iTab, addrBreak); VdbeCoverage(v);
codeOffset(v, p->iOffset, addrContinue);
sqlite3VdbeAddOp3(v, OP_Column, iTab, nKey+1, regRow);
iSortTab = iTab;
p5 = 0;
}
for(i=0; i<nSortData; i++){
sqlite3VdbeAddOp3(v, OP_Column, iSortTab, nKey+1+i, regRow+i);
if( i==0 ) sqlite3VdbeChangeP5(v, p5);
VdbeComment((v, "%s", aOutEx[i].zName ? aOutEx[i].zName : aOutEx[i].zSpan));
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struct ExprList_item *aOutEx = p->pEList->a;
#endif
if( pSort->labelBkOut ){
sqlite3VdbeAddOp2(v, OP_Gosub, pSort->regReturn, pSort->labelBkOut);
sqlite3VdbeAddOp2(v, OP_Goto, 0, addrBreak);
sqlite3VdbeResolveLabel(v, pSort->labelBkOut);
}
iTab = pSort->iECursor;
regRow = sqlite3GetTempReg(pParse);
if( eDest==SRT_Output || eDest==SRT_Coroutine ){
regRowid = 0;
regRow = pDest->iSdst;
nSortData = nColumn;
................................................................................
regRow = sqlite3GetTempReg(pParse);
nSortData = 1;
}
nKey = pOrderBy->nExpr - pSort->nOBSat;
if( pSort->sortFlags & SORTFLAG_UseSorter ){
int regSortOut = ++pParse->nMem;
iSortTab = pParse->nTab++;
if( pSort->labelBkOut ){
addrOnce = sqlite3CodeOnce(pParse); VdbeCoverage(v);
}
sqlite3VdbeAddOp3(v, OP_OpenPseudo, iSortTab, regSortOut, nKey+1+nSortData);
if( addrOnce ) sqlite3VdbeJumpHere(v, addrOnce);
addr = 1 + sqlite3VdbeAddOp2(v, OP_SorterSort, iTab, addrBreak);
VdbeCoverage(v);
codeOffset(v, p->iOffset, addrContinue);
sqlite3VdbeAddOp2(v, OP_SorterData, iTab, regSortOut);
p5 = OPFLAG_CLEARCACHE;
}else{
addr = 1 + sqlite3VdbeAddOp2(v, OP_Sort, iTab, addrBreak); VdbeCoverage(v);
codeOffset(v, p->iOffset, addrContinue);
iSortTab = iTab;
p5 = 0;
}
for(i=0; i<nSortData; i++){
sqlite3VdbeAddOp3(v, OP_Column, iSortTab, nKey+1+i, regRow+i);
if( i==0 ) sqlite3VdbeChangeP5(v, p5);
VdbeComment((v, "%s", aOutEx[i].zName ? aOutEx[i].zName : aOutEx[i].zSpan));
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