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Update the NGQP to record which loops need be run in reverse order to

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satisfy ORDER BY clauses.

FossilOrigin-Name: 211f7a5374fe20a02535edc8b799a8a7136ff6b3
This commit is contained in:
drh
2013-05-27 17:59:37 +00:00
parent 3bd26f0543
commit 88da644f2c
4 changed files with 48 additions and 51 deletions
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82
src/where.c
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@@ -5839,8 +5839,9 @@ static int wherePathSatisfiesOrderBy(
WhereLoop *pLast, /* Add this WhereLoop to the end of pPath->aLoop[] */
Bitmask *pRevMask /* Mask of WhereLoops to run in reverse order */
){
u8 revSet;
u8 rev;
u8 revSet; /* True if rev is known */
u8 rev; /* Composite sort order */
u8 revIdx; /* Index sort order */
u8 isUnique;
u8 requireUnique = 0;
u16 nColumn;
@@ -5890,7 +5891,7 @@ static int wherePathSatisfiesOrderBy(
** column reference */
nOrderBy = pOrderBy->nExpr;
for(i=0; i<nOrderBy; i++){
pOBExpr = sqlite3ExprSkipCollate(pOrderBy->a[nUsed].pExpr);
pOBExpr = sqlite3ExprSkipCollate(pOrderBy->a[i].pExpr);
if( pOBExpr->op!=TK_COLUMN ) return 0;
}
@@ -5902,7 +5903,7 @@ static int wherePathSatisfiesOrderBy(
if( (pLoop->wsFlags & WHERE_COLUMN_IN)!=0 ) isUnique = 0;
if( pLoop->u.btree.nEq!=1 ) isUnique = 0;
pIndex = 0;
nColumn = 1;
nColumn = 0;
}else if( (pIndex = pLoop->u.btree.pIndex)==0 || pIndex->bUnordered ){
return 0;
}else{
@@ -5921,31 +5922,31 @@ static int wherePathSatisfiesOrderBy(
iCur = pWInfo->pTabList->a[pLoop->iTab].iCursor;
j = 0;
revSet = rev = 0;
for(j=0; j<nColumn && nUsed<nOrderBy; j++, nUsed++){
for(j=0; j<=nColumn && nUsed<nOrderBy; j++, nUsed++){
pOBExpr = sqlite3ExprSkipCollate(pOrderBy->a[nUsed].pExpr);
assert( pOBExpr->op==TK_COLUMN );
if( pOBExpr->iTable!=iCur ) break;
if( pIndex==0 ){
if( pOBExpr->iColumn<0 && j==0 ){
isUnique = 1;
rev = pOrderBy->a[nUsed].sortOrder;
}else if( isUnique ){
continue;
}else{
return 0;
}
}
if( isUnique ) continue;
iColumn = pIndex->aiColumn[j];
if( iColumn==pIndex->pTable->iPKey ) iColumn = -1;
if( pOBExpr->iColumn!=iColumn ) return 0;
pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[nUsed].pExpr);
if( !pColl ) pColl = db->pDfltColl;
if( sqlite3StrICmp(pColl->zName, pIndex->azColl[j])!=0 ) return 0;
if( revSet ){
if( pIndex->aSortOrder[j]!=rev ) return 0;
if( j<nColumn ){
/* Normal index columns */
iColumn = pIndex->aiColumn[j];
revIdx = pIndex->aSortOrder[j];
if( iColumn==pIndex->pTable->iPKey ) iColumn = -1;
}else{
rev = pIndex->aSortOrder[j];
/* The ROWID column at the end */
iColumn = -1;
revIdx = 0;
}
if( pOBExpr->iColumn!=iColumn ) return 0;
if( iColumn>=0 ){
pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[nUsed].pExpr);
if( !pColl ) pColl = db->pDfltColl;
if( sqlite3StrICmp(pColl->zName, pIndex->azColl[j])!=0 ) return 0;
}
if( revSet ){
if( (rev ^ revIdx)!=pOrderBy->a[nUsed].sortOrder ) return 0;
}else{
rev = revIdx ^ pOrderBy->a[nUsed].sortOrder;
revSet = 1;
}
}
@@ -6000,6 +6001,9 @@ static int wherePathSolver(WhereInfo *pWInfo, double nRowEst){
db = pWInfo->pParse->db;
nLoop = pWInfo->nLevel;
assert( nLoop<=pWInfo->pTabList->nSrc );
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace>=2 ) sqlite3DebugPrintf("---- begin solver\n");
#endif
/* Allocate and initialize space for aTo and aFrom */
ii = (sizeof(WherePath)+sizeof(WhereLoop*)*nLoop)*mxChoice*2;
@@ -6020,28 +6024,14 @@ static int wherePathSolver(WhereInfo *pWInfo, double nRowEst){
/* Precompute the cost of sorting the final result set, if the caller
** to sqlite3WhereBegin() was concerned about sorting */
rSortCost = (double)0;
if( pWInfo->pOrderBy==0 || nRowEst<0.0 ){
if( pWInfo->pOrderBy==0 || nRowEst<=0.0 ){
aFrom[0].isOrderedValid = 1;
}else{
/* Compute an estimate on the cost to sort the entire result set */
#if 0
rSortCost = (double)1;
for(pWLoop=pWInfo->pLoops; pWLoop; pWLoop=pNext){
pNext = pWLoop->pNextLoop;
rCost = pWLoop->nOut;
while( pNext && pNext->iTab==pWLoop->iTab ){
if( pNext->nOut<rCost ) rCost = pNext->nOut;
pNext = pNext->pNextLoop;
}
rSortCost *= rCost;
}
rSortCost *= estLog(rSortCost);
#else
rSortCost = nRowEst*estLog(nRowEst);
#endif
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace>=2 ){
sqlite3DebugPrintf("--solver sort cost=%-7.2g\n", rSortCost);
sqlite3DebugPrintf("---- sort cost=%-7.2g\n", rSortCost);
}
#endif
}
@@ -6162,9 +6152,14 @@ static int wherePathSolver(WhereInfo *pWInfo, double nRowEst){
if( sqlite3WhereTrace>=2 ){
sqlite3DebugPrintf("---- after round %d ----\n", iLoop);
for(ii=0, pTo=aTo; ii<nTo; ii++, pTo++){
sqlite3DebugPrintf(" %s cost=%-7.2g nrow=%-7.2g order=%c\n",
sqlite3DebugPrintf(" %s cost=%-7.2g nrow=%-7.2g order=%c",
wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
pTo->isOrderedValid ? (pTo->isOrdered ? 'Y' : 'N') : '?');
if( pTo->isOrderedValid && pTo->isOrdered ){
sqlite3DebugPrintf(" rev=0x%llx\n", pTo->revLoop);
}else{
sqlite3DebugPrintf("\n");
}
}
}
#endif
@@ -6192,6 +6187,7 @@ static int wherePathSolver(WhereInfo *pWInfo, double nRowEst){
}
if( pFrom->isOrdered ){
pWInfo->nOBSat = pWInfo->pOrderBy->nExpr;
pWInfo->revMask = pFrom->revLoop;
}
pWInfo->nRowOut = pFrom->nRow;
@@ -6468,9 +6464,9 @@ WhereInfo *sqlite3WhereBegin(
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace ){
int ii;
sqlite3DebugPrintf("------------ Solution -------------");
sqlite3DebugPrintf("---- Solution");
if( pWInfo->nOBSat ){
sqlite3DebugPrintf(" ORDER BY omitted\n");
sqlite3DebugPrintf(" ORDER BY omitted rev=0x%llx\n", pWInfo->revMask);
}else{
sqlite3DebugPrintf("\n");
}