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Enhance the plan solver to take into account the number of output rows when

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computing the set of paths to retain for the next cycle.

FossilOrigin-Name: 1a46a7242313da96420985fa52e1de3f84533e5b
This commit is contained in:
drh
2013-09-06 17:45:42 +00:00
parent cca9f3d291
commit fde1e6bc37
4 changed files with 46 additions and 36 deletions
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61
src/where.c
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@@ -5306,9 +5306,12 @@ static int wherePathSolver(WhereInfo *pWInfo, WhereCost nRowEst){
sqlite3 *db; /* The database connection */
int iLoop; /* Loop counter over the terms of the join */
int ii, jj; /* Loop counters */
WhereCost rCost; /* Cost of a path */
WhereCost mxCost = 0; /* Maximum cost of a set of paths */
WhereCost rSortCost; /* Cost to do a sort */
int mxI = 0; /* Index of next entry to replace */
WhereCost rCost; /* Cost of a path */
WhereCost nOut; /* Number of outputs */
WhereCost mxCost = 0; /* Maximum cost of a set of paths */
WhereCost mxOut = 0; /* Maximum nOut value on the set of paths */
WhereCost rSortCost; /* Cost to do a sort */
int nTo, nFrom; /* Number of valid entries in aTo[] and aFrom[] */
WherePath *aFrom; /* All nFrom paths at the previous level */
WherePath *aTo; /* The nTo best paths at the current level */
@@ -5377,6 +5380,7 @@ static int wherePathSolver(WhereInfo *pWInfo, WhereCost nRowEst){
** Compute its cost */
rCost = whereCostAdd(pWLoop->rSetup,pWLoop->rRun + pFrom->nRow);
rCost = whereCostAdd(rCost, pFrom->rCost);
nOut = pFrom->nRow + pWLoop->nOut;
maskNew = pFrom->maskLoop | pWLoop->maskSelf;
if( !isOrderedValid ){
switch( wherePathSatisfiesOrderBy(pWInfo,
@@ -5399,17 +5403,23 @@ static int wherePathSolver(WhereInfo *pWInfo, WhereCost nRowEst){
}
/* Check to see if pWLoop should be added to the mxChoice best so far */
for(jj=0, pTo=aTo; jj<nTo; jj++, pTo++){
if( pTo->maskLoop==maskNew && pTo->isOrderedValid==isOrderedValid ){
if( pTo->maskLoop==maskNew
&& pTo->isOrderedValid==isOrderedValid
&& ((pTo->rCost<=rCost && pTo->nRow<=nOut) ||
(pTo->rCost>=rCost && pTo->nRow>=nOut))
){
testcase( jj==nTo-1 );
break;
}
}
if( jj>=nTo ){
if( nTo>=mxChoice && rCost>=mxCost ){
if( nTo>=mxChoice
&& (rCost>mxCost || (rCost==mxCost && nOut>=mxOut))
){
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf("Skip %s cost=%3d order=%c\n",
wherePathName(pFrom, iLoop, pWLoop), rCost,
sqlite3DebugPrintf("Skip %s cost=%-3d,%3d order=%c\n",
wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
isOrderedValid ? (isOrdered ? 'Y' : 'N') : '?');
}
#endif
@@ -5421,26 +5431,26 @@ static int wherePathSolver(WhereInfo *pWInfo, WhereCost nRowEst){
jj = nTo++;
}else{
/* New path replaces the prior worst to keep count below mxChoice */
for(jj=nTo-1; aTo[jj].rCost<mxCost; jj--){ assert(jj>0); }
jj = mxI;
}
pTo = &aTo[jj];
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf("New %s cost=%-3d order=%c\n",
wherePathName(pFrom, iLoop, pWLoop), rCost,
sqlite3DebugPrintf("New %s cost=%-3d,%3d order=%c\n",
wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
isOrderedValid ? (isOrdered ? 'Y' : 'N') : '?');
}
#endif
}else{
if( pTo->rCost<=rCost ){
if( pTo->rCost<=rCost && pTo->nRow<=nOut ){
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf(
"Skip %s cost=%-3d order=%c",
wherePathName(pFrom, iLoop, pWLoop), rCost,
"Skip %s cost=%-3d,%3d order=%c",
wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
isOrderedValid ? (isOrdered ? 'Y' : 'N') : '?');
sqlite3DebugPrintf(" vs %s cost=%-3d order=%c\n",
wherePathName(pTo, iLoop+1, 0), pTo->rCost,
sqlite3DebugPrintf(" vs %s cost=%-3d,%d order=%c\n",
wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
pTo->isOrderedValid ? (pTo->isOrdered ? 'Y' : 'N') : '?');
}
#endif
@@ -5452,11 +5462,11 @@ static int wherePathSolver(WhereInfo *pWInfo, WhereCost nRowEst){
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf(
"Update %s cost=%-3d order=%c",
wherePathName(pFrom, iLoop, pWLoop), rCost,
"Update %s cost=%-3d,%3d order=%c",
wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
isOrderedValid ? (isOrdered ? 'Y' : 'N') : '?');
sqlite3DebugPrintf(" was %s cost=%-3d order=%c\n",
wherePathName(pTo, iLoop+1, 0), pTo->rCost,
sqlite3DebugPrintf(" was %s cost=%-3d,%3d order=%c\n",
wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
pTo->isOrderedValid ? (pTo->isOrdered ? 'Y' : 'N') : '?');
}
#endif
@@ -5464,16 +5474,22 @@ static int wherePathSolver(WhereInfo *pWInfo, WhereCost nRowEst){
/* pWLoop is a winner. Add it to the set of best so far */
pTo->maskLoop = pFrom->maskLoop | pWLoop->maskSelf;
pTo->revLoop = revMask;
pTo->nRow = pFrom->nRow + pWLoop->nOut;
pTo->nRow = nOut;
pTo->rCost = rCost;
pTo->isOrderedValid = isOrderedValid;
pTo->isOrdered = isOrdered;
memcpy(pTo->aLoop, pFrom->aLoop, sizeof(WhereLoop*)*iLoop);
pTo->aLoop[iLoop] = pWLoop;
if( nTo>=mxChoice ){
mxI = 0;
mxCost = aTo[0].rCost;
mxOut = aTo[0].nRow;
for(jj=1, pTo=&aTo[1]; jj<mxChoice; jj++, pTo++){
if( pTo->rCost>mxCost ) mxCost = pTo->rCost;
if( pTo->rCost>mxCost || (pTo->rCost==mxCost && pTo->nRow>mxOut) ){
mxCost = pTo->rCost;
mxOut = pTo->nRow;
mxI = jj;
}
}
}
}
@@ -5510,12 +5526,9 @@ static int wherePathSolver(WhereInfo *pWInfo, WhereCost nRowEst){
/* Find the lowest cost path. pFrom will be left pointing to that path */
pFrom = aFrom;
assert( nFrom==1 );
#if 0 /* The following is needed if nFrom is ever more than 1 */
for(ii=1; ii<nFrom; ii++){
if( pFrom->rCost>aFrom[ii].rCost ) pFrom = &aFrom[ii];
}
#endif
assert( pWInfo->nLevel==nLoop );
/* Load the lowest cost path into pWInfo */
for(iLoop=0; iLoop<nLoop; iLoop++){