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Overview
| Comment: | Enhance the plan solver to take into account the number of output rows when computing the set of paths to retain for the next cycle. |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | unlikely-func |
| Files: | files | file ages | folders |
| SHA1: |
1a46a7242313da96420985fa52e1de3f |
| User & Date: | drh 2013-09-06 17:45:42 |
Context
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2013-09-07
| ||
| 00:29 | Continuing refinements of the logic to take WHERE clause terms not used for indexing into account when computing the number of output rows from each table. (check-in: b65dc534 user: drh tags: unlikely-func) | |
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2013-09-06
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| 17:45 | Enhance the plan solver to take into account the number of output rows when computing the set of paths to retain for the next cycle. (check-in: 1a46a724 user: drh tags: unlikely-func) | |
| 15:23 | Initial implementation of the unlikely() SQL function used as a hint to the query planner. (check-in: 036fc37a user: drh tags: unlikely-func) | |
Changes
Changes to src/resolve.c.
701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 |
pExpr->iTable = exprProbability(pList->a[1].pExpr);
if( pExpr->iTable<0 ){
sqlite3ErrorMsg(pParse, "second parameter to unlikely() must be "
"between 0.0 and 1.0");
pNC->nErr++;
}
}else{
pExpr->iTable = 100;
}
}
}
#ifndef SQLITE_OMIT_AUTHORIZATION
if( pDef ){
auth = sqlite3AuthCheck(pParse, SQLITE_FUNCTION, 0, pDef->zName, 0);
if( auth!=SQLITE_OK ){
|
| |
701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 |
pExpr->iTable = exprProbability(pList->a[1].pExpr);
if( pExpr->iTable<0 ){
sqlite3ErrorMsg(pParse, "second parameter to unlikely() must be "
"between 0.0 and 1.0");
pNC->nErr++;
}
}else{
pExpr->iTable = 75;
}
}
}
#ifndef SQLITE_OMIT_AUTHORIZATION
if( pDef ){
auth = sqlite3AuthCheck(pParse, SQLITE_FUNCTION, 0, pDef->zName, 0);
if( auth!=SQLITE_OK ){
|
Changes to src/where.c.
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static int wherePathSolver(WhereInfo *pWInfo, WhereCost nRowEst){
int mxChoice; /* Maximum number of simultaneous paths tracked */
int nLoop; /* Number of terms in the join */
Parse *pParse; /* Parsing context */
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 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 */
WherePath *pFrom; /* An element of aFrom[] that we are working on */
WherePath *pTo; /* An element of aTo[] that we are working on */
WhereLoop *pWLoop; /* One of the WhereLoop objects */
WhereLoop **pX; /* Used to divy up the pSpace memory */
................................................................................
u8 isOrdered = pFrom->isOrdered;
if( (pWLoop->prereq & ~pFrom->maskLoop)!=0 ) continue;
if( (pWLoop->maskSelf & pFrom->maskLoop)!=0 ) continue;
/* At this point, pWLoop is a candidate to be the next loop.
** Compute its cost */
rCost = whereCostAdd(pWLoop->rSetup,pWLoop->rRun + pFrom->nRow);
rCost = whereCostAdd(rCost, pFrom->rCost);
maskNew = pFrom->maskLoop | pWLoop->maskSelf;
if( !isOrderedValid ){
switch( wherePathSatisfiesOrderBy(pWInfo,
pWInfo->pOrderBy, pFrom, pWInfo->wctrlFlags,
iLoop, pWLoop, &revMask) ){
case 1: /* Yes. pFrom+pWLoop does satisfy the ORDER BY clause */
isOrdered = 1;
................................................................................
break;
}
}else{
revMask = pFrom->revLoop;
}
/* 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 ){
testcase( jj==nTo-1 );
break;
}
}
if( jj>=nTo ){
if( nTo>=mxChoice && rCost>=mxCost ){
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf("Skip %s cost=%3d order=%c\n",
wherePathName(pFrom, iLoop, pWLoop), rCost,
isOrderedValid ? (isOrdered ? 'Y' : 'N') : '?');
}
#endif
continue;
}
/* Add a new Path to the aTo[] set */
if( nTo<mxChoice ){
/* Increase the size of the aTo set by one */
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); }
}
pTo = &aTo[jj];
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf("New %s cost=%-3d order=%c\n",
wherePathName(pFrom, iLoop, pWLoop), rCost,
isOrderedValid ? (isOrdered ? 'Y' : 'N') : '?');
}
#endif
}else{
if( pTo->rCost<=rCost ){
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf(
"Skip %s cost=%-3d order=%c",
wherePathName(pFrom, iLoop, pWLoop), rCost,
isOrderedValid ? (isOrdered ? 'Y' : 'N') : '?');
sqlite3DebugPrintf(" vs %s cost=%-3d order=%c\n",
wherePathName(pTo, iLoop+1, 0), pTo->rCost,
pTo->isOrderedValid ? (pTo->isOrdered ? 'Y' : 'N') : '?');
}
#endif
testcase( pTo->rCost==rCost );
continue;
}
testcase( pTo->rCost==rCost+1 );
/* A new and better score for a previously created equivalent path */
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf(
"Update %s cost=%-3d order=%c",
wherePathName(pFrom, iLoop, pWLoop), rCost,
isOrderedValid ? (isOrdered ? 'Y' : 'N') : '?');
sqlite3DebugPrintf(" was %s cost=%-3d order=%c\n",
wherePathName(pTo, iLoop+1, 0), pTo->rCost,
pTo->isOrderedValid ? (pTo->isOrdered ? 'Y' : 'N') : '?');
}
#endif
}
/* 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->rCost = rCost;
pTo->isOrderedValid = isOrderedValid;
pTo->isOrdered = isOrdered;
memcpy(pTo->aLoop, pFrom->aLoop, sizeof(WhereLoop*)*iLoop);
pTo->aLoop[iLoop] = pWLoop;
if( nTo>=mxChoice ){
mxCost = aTo[0].rCost;
for(jj=1, pTo=&aTo[1]; jj<mxChoice; jj++, pTo++){
if( pTo->rCost>mxCost ) mxCost = pTo->rCost;
}
}
}
}
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace>=2 ){
................................................................................
sqlite3ErrorMsg(pParse, "no query solution");
sqlite3DbFree(db, pSpace);
return SQLITE_ERROR;
}
/* 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++){
WhereLevel *pLevel = pWInfo->a + iLoop;
pLevel->pWLoop = pWLoop = pFrom->aLoop[iLoop];
pLevel->iFrom = pWLoop->iTab;
pLevel->iTabCur = pWInfo->pTabList->a[pLevel->iFrom].iCursor;
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static int wherePathSolver(WhereInfo *pWInfo, WhereCost nRowEst){
int mxChoice; /* Maximum number of simultaneous paths tracked */
int nLoop; /* Number of terms in the join */
Parse *pParse; /* Parsing context */
sqlite3 *db; /* The database connection */
int iLoop; /* Loop counter over the terms of the join */
int ii, jj; /* Loop counters */
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 */
WherePath *pFrom; /* An element of aFrom[] that we are working on */
WherePath *pTo; /* An element of aTo[] that we are working on */
WhereLoop *pWLoop; /* One of the WhereLoop objects */
WhereLoop **pX; /* Used to divy up the pSpace memory */
................................................................................
u8 isOrdered = pFrom->isOrdered;
if( (pWLoop->prereq & ~pFrom->maskLoop)!=0 ) continue;
if( (pWLoop->maskSelf & pFrom->maskLoop)!=0 ) continue;
/* At this point, pWLoop is a candidate to be the next loop.
** 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,
pWInfo->pOrderBy, pFrom, pWInfo->wctrlFlags,
iLoop, pWLoop, &revMask) ){
case 1: /* Yes. pFrom+pWLoop does satisfy the ORDER BY clause */
isOrdered = 1;
................................................................................
break;
}
}else{
revMask = pFrom->revLoop;
}
/* 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
&& ((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 || (rCost==mxCost && nOut>=mxOut))
){
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf("Skip %s cost=%-3d,%3d order=%c\n",
wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
isOrderedValid ? (isOrdered ? 'Y' : 'N') : '?');
}
#endif
continue;
}
/* Add a new Path to the aTo[] set */
if( nTo<mxChoice ){
/* Increase the size of the aTo set by one */
jj = nTo++;
}else{
/* New path replaces the prior worst to keep count below mxChoice */
jj = mxI;
}
pTo = &aTo[jj];
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace&0x4 ){
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 && pTo->nRow<=nOut ){
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf(
"Skip %s cost=%-3d,%3d order=%c",
wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
isOrderedValid ? (isOrdered ? 'Y' : 'N') : '?');
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
testcase( pTo->rCost==rCost );
continue;
}
testcase( pTo->rCost==rCost+1 );
/* A new and better score for a previously created equivalent path */
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf(
"Update %s cost=%-3d,%3d order=%c",
wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
isOrderedValid ? (isOrdered ? 'Y' : 'N') : '?');
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
}
/* pWLoop is a winner. Add it to the set of best so far */
pTo->maskLoop = pFrom->maskLoop | pWLoop->maskSelf;
pTo->revLoop = revMask;
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 || (pTo->rCost==mxCost && pTo->nRow>mxOut) ){
mxCost = pTo->rCost;
mxOut = pTo->nRow;
mxI = jj;
}
}
}
}
}
#ifdef WHERETRACE_ENABLED
if( sqlite3WhereTrace>=2 ){
................................................................................
sqlite3ErrorMsg(pParse, "no query solution");
sqlite3DbFree(db, pSpace);
return SQLITE_ERROR;
}
/* Find the lowest cost path. pFrom will be left pointing to that path */
pFrom = aFrom;
for(ii=1; ii<nFrom; ii++){
if( pFrom->rCost>aFrom[ii].rCost ) pFrom = &aFrom[ii];
}
assert( pWInfo->nLevel==nLoop );
/* Load the lowest cost path into pWInfo */
for(iLoop=0; iLoop<nLoop; iLoop++){
WhereLevel *pLevel = pWInfo->a + iLoop;
pLevel->pWLoop = pWLoop = pFrom->aLoop[iLoop];
pLevel->iFrom = pWLoop->iTab;
pLevel->iTabCur = pWInfo->pTabList->a[pLevel->iFrom].iCursor;
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