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Overview
| Comment: | Make sure the WHERE_IDX_ONLY flag is not set on query plans that will not be using an index. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | fullscan-covering-index |
| Files: | files | file ages | folders |
| SHA1: | 698b2a28004a9a2f0eabaadf36d833da |
| User & Date: | drh 2012-09-17 21:24:01 |
Context
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2012-09-19
| ||
| 00:35 | Merge the covering-index-scan optimization into trunk. check-in: ddd5d789 user: drh tags: trunk | |
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2012-09-17
| ||
| 21:24 | Make sure the WHERE_IDX_ONLY flag is not set on query plans that will not be using an index. Closed-Leaf check-in: 698b2a28 user: drh tags: fullscan-covering-index | |
| 20:44 | Add the ability to disable the covering-index-scan optimization at compile-time, start-time, or at run-time. Add test cases to check this configurability. check-in: ccb8ecc3 user: drh tags: fullscan-covering-index | |
Changes
Changes to src/where.c.
3219 3220 3221 3222 3223 3224 3225 3226 3227 3228 3229 3230 3231 3232 |
** We add an additional 4x penalty to full table scans. This causes
** the cost function to err on the side of choosing an index over
** choosing a full scan. This 4x full-scan penalty is an arguable
** decision and one which we expect to revisit in the future. But
** it seems to be working well enough at the moment.
*/
cost = aiRowEst[0]*4;
}else{
log10N = estLog(aiRowEst[0]);
cost = nRow;
if( pIdx ){
if( bLookup ){
/* For an index lookup followed by a table lookup:
** nInMul index searches to find the start of each index range
|
> |
3219 3220 3221 3222 3223 3224 3225 3226 3227 3228 3229 3230 3231 3232 3233 |
** We add an additional 4x penalty to full table scans. This causes
** the cost function to err on the side of choosing an index over
** choosing a full scan. This 4x full-scan penalty is an arguable
** decision and one which we expect to revisit in the future. But
** it seems to be working well enough at the moment.
*/
cost = aiRowEst[0]*4;
wsFlags &= ~WHERE_IDX_ONLY;
}else{
log10N = estLog(aiRowEst[0]);
cost = nRow;
if( pIdx ){
if( bLookup ){
/* For an index lookup followed by a table lookup:
** nInMul index searches to find the start of each index range
|