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Overview
| Comment: | Add WHERETRACE debugging output to the whereLoopAdjustCost() routine. |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
ec1e942f08548695ff02645b3f3cd6bb |
| User & Date: | drh 2014-10-21 16:01:40 |
| Original Comment: | Improvements to the WHERETRACE debugging logic. |
Context
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2014-10-21
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| 18:16 | Further tuning of the cost estimates for skip-scan loops, especially for cases when skip-scan loops are in competition with regular loops. check-in: a27861c2 user: drh tags: trunk | |
| 16:01 | Add WHERETRACE debugging output to the whereLoopAdjustCost() routine. check-in: ec1e942f user: drh tags: trunk | |
| 01:05 | If a skip-scan is a proper subset of some other scan, then adjust the cost of the skip-scan upward so that it is more costly than the other scan. Such a cost imbalance can arise under STAT4 because of difficulties in getting an accurate estimate for skip-scans. check-in: f4b22a26 user: drh tags: trunk | |
Changes
Changes to src/where.c.
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if( (pTemplate->wsFlags & WHERE_INDEXED)==0 ) return;
for(; p; p=p->pNextLoop){
if( p->iTab!=pTemplate->iTab ) continue;
if( (p->wsFlags & WHERE_INDEXED)==0 ) continue;
if( whereLoopCheaperProperSubset(p, pTemplate) ){
/* Adjust pTemplate cost downward so that it is cheaper than its
** subset p */
pTemplate->rRun = p->rRun;
pTemplate->nOut = p->nOut - 1;
}else if( whereLoopCheaperProperSubset(pTemplate, p) ){
/* Adjust pTemplate cost upward so that it is costlier than p since
** pTemplate is a proper subset of p */
pTemplate->rRun = p->rRun;
pTemplate->nOut = p->nOut + 1;
}
}
}
/*
................................................................................
}
}
}
}
}
#ifdef WHERETRACE_ENABLED /* >=2 */
if( sqlite3WhereTrace>=2 ){
sqlite3DebugPrintf("---- after round %d ----\n", iLoop);
for(ii=0, pTo=aTo; ii<nTo; ii++, pTo++){
sqlite3DebugPrintf(" %s cost=%-3d nrow=%-3d order=%c",
wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
pTo->isOrdered>=0 ? (pTo->isOrdered+'0') : '?');
if( pTo->isOrdered>0 ){
sqlite3DebugPrintf(" rev=0x%llx\n", pTo->revLoop);
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if( (pTemplate->wsFlags & WHERE_INDEXED)==0 ) return;
for(; p; p=p->pNextLoop){
if( p->iTab!=pTemplate->iTab ) continue;
if( (p->wsFlags & WHERE_INDEXED)==0 ) continue;
if( whereLoopCheaperProperSubset(p, pTemplate) ){
/* Adjust pTemplate cost downward so that it is cheaper than its
** subset p */
WHERETRACE(0x80,("subset cost adjustment %d,%d to %d,%d\n",
pTemplate->rRun, pTemplate->nOut, p->rRun, p->nOut-1));
pTemplate->rRun = p->rRun;
pTemplate->nOut = p->nOut - 1;
}else if( whereLoopCheaperProperSubset(pTemplate, p) ){
/* Adjust pTemplate cost upward so that it is costlier than p since
** pTemplate is a proper subset of p */
WHERETRACE(0x80,("subset cost adjustment %d,%d to %d,%d\n",
pTemplate->rRun, pTemplate->nOut, p->rRun, p->nOut+1));
pTemplate->rRun = p->rRun;
pTemplate->nOut = p->nOut + 1;
}
}
}
/*
................................................................................
}
}
}
}
}
#ifdef WHERETRACE_ENABLED /* >=2 */
if( sqlite3WhereTrace & 0x02 ){
sqlite3DebugPrintf("---- after round %d ----\n", iLoop);
for(ii=0, pTo=aTo; ii<nTo; ii++, pTo++){
sqlite3DebugPrintf(" %s cost=%-3d nrow=%-3d order=%c",
wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
pTo->isOrdered>=0 ? (pTo->isOrdered+'0') : '?');
if( pTo->isOrdered>0 ){
sqlite3DebugPrintf(" rev=0x%llx\n", pTo->revLoop);
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