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Overview
| Comment: | When planning a query using sorting, resolve ties in the solver by selecting loop plans with the smaller unsorted cost. |
|---|---|
| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | descendants | both | branch-3.8.9 |
| Files: | files | file ages | folders |
| SHA3-256: |
962531e7c1f3ff604271ddf9f47b6234 |
| User & Date: | drh 2017-05-22 00:27:20.133 |
Context
|
2017-05-24
| ||
| 04:32 | Fix a problem in STAT4 equality estimation for multi-column indexes introduced by check-in [3e0590dee0e68cc1599]. (check-in: 19dad0a720 user: drh tags: branch-3.8.9) | |
|
2017-05-22
| ||
| 00:45 | When planning a query using sorting, resolve ties in the solver by selecting loop plans with the smaller unsorted cost. (check-in: f261678c90 user: drh tags: trunk) | |
| 00:27 | When planning a query using sorting, resolve ties in the solver by selecting loop plans with the smaller unsorted cost. (check-in: 962531e7c1 user: drh tags: branch-3.8.9) | |
|
2017-01-11
| ||
| 14:21 | In the STAT4 computations, ensure that the aAvgEq values do not go negative. (check-in: 4f83f6806a user: drh tags: branch-3.8.9) | |
Changes
Changes to src/where.c.
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&& (rCost>mxCost || (rCost==mxCost && rUnsorted>=mxUnsorted))
){
/* The current candidate is no better than any of the mxChoice
** paths currently in the best-so-far buffer. So discard
** this candidate as not viable. */
#ifdef WHERETRACE_ENABLED /* 0x4 */
if( sqlite3WhereTrace&0x4 ){
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&& (rCost>mxCost || (rCost==mxCost && rUnsorted>=mxUnsorted))
){
/* The current candidate is no better than any of the mxChoice
** paths currently in the best-so-far buffer. So discard
** this candidate as not viable. */
#ifdef WHERETRACE_ENABLED /* 0x4 */
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf("Skip %s cost=%-3d,%3d,%3d order=%c\n",
wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, rUnsorted,
isOrdered>=0 ? isOrdered+'0' : '?');
}
#endif
continue;
}
/* If we reach this points it means that the new candidate path
** needs to be added to the set of best-so-far paths. */
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 /* 0x4 */
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf("New %s cost=%-3d,%3d,%3d order=%c\n",
wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, rUnsorted,
isOrdered>=0 ? isOrdered+'0' : '?');
}
#endif
}else{
/* Control reaches here if best-so-far path pTo=aTo[jj] covers the
** same set of loops and has the same isOrdered setting as the
** candidate path. Check to see if the candidate should replace
** pTo or if the candidate should be skipped.
**
** The conditional is an expanded vector comparison equivalent to:
** (pTo->rCost,pTo->nRow,pTo->rUnsorted) <= (rCost,nOut,rUnsorted)
*/
if( pTo->rCost<rCost
|| (pTo->rCost==rCost
&& (pTo->nRow<nOut
|| (pTo->nRow==nOut && pTo->rUnsorted<=rUnsorted)
)
)
){
#ifdef WHERETRACE_ENABLED /* 0x4 */
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf(
"Skip %s cost=%-3d,%3d,%3d order=%c",
wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, rUnsorted,
isOrdered>=0 ? isOrdered+'0' : '?');
sqlite3DebugPrintf(" vs %s cost=%-3d,%3d,%3d order=%c\n",
wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
pTo->rUnsorted, pTo->isOrdered>=0 ? pTo->isOrdered+'0' : '?');
}
#endif
/* Discard the candidate path from further consideration */
testcase( pTo->rCost==rCost );
continue;
}
testcase( pTo->rCost==rCost+1 );
/* Control reaches here if the candidate path is better than the
** pTo path. Replace pTo with the candidate. */
#ifdef WHERETRACE_ENABLED /* 0x4 */
if( sqlite3WhereTrace&0x4 ){
sqlite3DebugPrintf(
"Update %s cost=%-3d,%3d,%3d order=%c",
wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, rUnsorted,
isOrdered>=0 ? isOrdered+'0' : '?');
sqlite3DebugPrintf(" was %s cost=%-3d,%3d,%3d order=%c\n",
wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
pTo->rUnsorted, pTo->isOrdered>=0 ? pTo->isOrdered+'0' : '?');
}
#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;
|
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