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Overview
| Comment: | Fix a missing word in a comment. Enhance the "wheretrace" debugging output to show the estimated cost of each table option while planning the join order. |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
ac4e119a87497f2e422ff1cb711112ed |
| User & Date: | drh 2013-01-15 18:49:07 |
Context
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2013-01-16
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| 00:46 | Improvements to query planning for joins: Avoid unnecessary calls to "optimal scan" checks in cases where table reordering is not possible. Make sure optimal scan checks are carried out for CROSS JOINs and LEFT JOINs. (check-in: d5ebb787 user: drh tags: trunk) | |
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2013-01-15
| ||
| 18:49 | Fix a missing word in a comment. Enhance the "wheretrace" debugging output to show the estimated cost of each table option while planning the join order. (check-in: ac4e119a user: drh tags: trunk) | |
| 16:15 | Clarification to a comment in where.c. No code changes. (check-in: 04507c17 user: drh tags: trunk) | |
Changes
Changes to src/where.c.
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assert( p->pOrderBy || (p->cost.plan.wsFlags&WHERE_ORDERED)==0 );
assert( p->cost.plan.u.pIdx==0 || (p->cost.plan.wsFlags&WHERE_ROWID_EQ)==0 );
assert( pSrc->pIndex==0
|| p->cost.plan.u.pIdx==0
|| p->cost.plan.u.pIdx==pSrc->pIndex
);
WHERETRACE((" best index is: %s\n",
p->cost.plan.u.pIdx ? p->cost.plan.u.pIdx->zName : "ipk"));
bestOrClauseIndex(p);
bestAutomaticIndex(p);
p->cost.plan.wsFlags |= eqTermMask;
}
/*
................................................................................
if( isOptimal && (sWBI.cost.plan.wsFlags & WHERE_NOT_FULLSCAN)==0 ){
notIndexed |= m;
}
if( isOptimal ){
pWInfo->a[j].rOptCost = sWBI.cost.rCost;
}else if( iFrom<nTabList-1 ){
/* If two or more tables have nearly the same outer loop cost,
** very different inner loop (optimal) cost, we want to choose
** for the outer loop that table which benefits the least from
** being in the inner loop. The following code scales the
** outer loop cost estimate to accomplish that. */
WHERETRACE((" scaling cost from %.1f to %.1f\n",
sWBI.cost.rCost,
sWBI.cost.rCost/pWInfo->a[j].rOptCost));
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assert( p->pOrderBy || (p->cost.plan.wsFlags&WHERE_ORDERED)==0 );
assert( p->cost.plan.u.pIdx==0 || (p->cost.plan.wsFlags&WHERE_ROWID_EQ)==0 );
assert( pSrc->pIndex==0
|| p->cost.plan.u.pIdx==0
|| p->cost.plan.u.pIdx==pSrc->pIndex
);
WHERETRACE((" best index is %s cost=%.1f\n",
p->cost.plan.u.pIdx ? p->cost.plan.u.pIdx->zName : "ipk",
p->cost.rCost));
bestOrClauseIndex(p);
bestAutomaticIndex(p);
p->cost.plan.wsFlags |= eqTermMask;
}
/*
................................................................................
if( isOptimal && (sWBI.cost.plan.wsFlags & WHERE_NOT_FULLSCAN)==0 ){
notIndexed |= m;
}
if( isOptimal ){
pWInfo->a[j].rOptCost = sWBI.cost.rCost;
}else if( iFrom<nTabList-1 ){
/* If two or more tables have nearly the same outer loop cost, but
** very different inner loop (optimal) cost, we want to choose
** for the outer loop that table which benefits the least from
** being in the inner loop. The following code scales the
** outer loop cost estimate to accomplish that. */
WHERETRACE((" scaling cost from %.1f to %.1f\n",
sWBI.cost.rCost,
sWBI.cost.rCost/pWInfo->a[j].rOptCost));
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