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Avoid unnecessary moving of content between registers during an ORDER BY.

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FossilOrigin-Name: 4f472accf072d9cb64f209923924b26f21b13d27
This commit is contained in:
drh
2014-03-24 18:08:15 +00:00
parent 3f802ebce2
commit fd0a2f9756
3 changed files with 35 additions and 19 deletions
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38
src/select.c
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@@ -463,19 +463,28 @@ static void pushOntoSorter(
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 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 = sqlite3GetTempRange(pParse, nBase); /* Regs for 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);
sqlite3VdbeAddOp3(v, OP_Move, regData, regBase+nExpr+1, nData);
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 */
@@ -515,7 +524,9 @@ static void pushOntoSorter(
sqlite3VdbeAddOp2(v, op, pSort->iECursor, regRecord);
if( nOBSat==0 ){
sqlite3ReleaseTempReg(pParse, regRecord);
sqlite3ReleaseTempRange(pParse, regBase, nBase);
if( nPrefixReg==0 ){
sqlite3ReleaseTempRange(pParse, regBase, nBase);
}
}
if( pSelect->iLimit ){
int addr1, addr2;
@@ -631,6 +642,7 @@ static void selectInnerLoop(
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 );
@@ -646,6 +658,10 @@ static void selectInnerLoop(
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 ){
@@ -762,10 +778,10 @@ static void selectInnerLoop(
case SRT_DistFifo:
case SRT_Table:
case SRT_EphemTab: {
int r1 = sqlite3GetTempReg(pParse);
int r1 = sqlite3GetTempRange(pParse, nPrefixReg+1);
testcase( eDest==SRT_Table );
testcase( eDest==SRT_EphemTab );
sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1);
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
@@ -780,7 +796,7 @@ static void selectInnerLoop(
}
#endif
if( pSort ){
pushOntoSorter(pParse, pSort, p, r1, 1);
pushOntoSorter(pParse, pSort, p, r1+nPrefixReg, 1, nPrefixReg);
}else{
int r2 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, r2);
@@ -788,7 +804,7 @@ static void selectInnerLoop(
sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
sqlite3ReleaseTempReg(pParse, r2);
}
sqlite3ReleaseTempReg(pParse, r1);
sqlite3ReleaseTempRange(pParse, r1, nPrefixReg+1);
break;
}
@@ -806,7 +822,7 @@ static void selectInnerLoop(
** 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);
pushOntoSorter(pParse, pSort, p, regResult, 1, nPrefixReg);
}else{
int r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp4(v, OP_MakeRecord, regResult,1,r1, &pDest->affSdst, 1);
@@ -832,7 +848,7 @@ static void selectInnerLoop(
case SRT_Mem: {
assert( nResultCol==1 );
if( pSort ){
pushOntoSorter(pParse, pSort, p, regResult, 1);
pushOntoSorter(pParse, pSort, p, regResult, 1, nPrefixReg);
}else{
sqlite3ExprCodeMove(pParse, regResult, iParm, 1);
/* The LIMIT clause will jump out of the loop for us */
@@ -846,7 +862,7 @@ static void selectInnerLoop(
testcase( eDest==SRT_Coroutine );
testcase( eDest==SRT_Output );
if( pSort ){
pushOntoSorter(pParse, pSort, p, regResult, nResultCol);
pushOntoSorter(pParse, pSort, p, regResult, nResultCol, nPrefixReg);
}else if( eDest==SRT_Coroutine ){
sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm);
}else{