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Overview
| Comment: | Restore additional ORDER BY optimizations that where broken by the recent ORDER BY fix. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | orderby-fix |
| Files: | files | file ages | folders |
| SHA1: | c77ee6e20d3a8c91a8bf4c9063c36a95c70e17cf |
| User & Date: | drh 2013-03-27 16:42:21 |
Context
|
2013-03-27
| ||
| 17:20 | In order to optimize out the ORDER BY clause, outer loops must generate values for ORDER BY terms that are unique or else the inner loops must generate no more than a single row. Fix for ticket [a179fe7465]. check-in: 2936f746 user: drh tags: trunk | |
| 16:42 | Restore additional ORDER BY optimizations that where broken by the recent ORDER BY fix. Closed-Leaf check-in: c77ee6e2 user: drh tags: orderby-fix | |
| 16:05 | Improved optimization of ORDER BY. check-in: 97e5c70f user: drh tags: orderby-fix | |
Changes
Changes to src/where.c.
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int outerObUnique; /* Outer loops generate different values in
** every row for the ORDER BY columns */
if( p->i==0 ){
nPriorSat = 0;
outerObUnique = 1;
}else{
nPriorSat = p->aLevel[p->i-1].plan.nOBSat;
if( (p->aLevel[p->i-1].plan.wsFlags & WHERE_ORDERED)==0 ){
/* This loop cannot be ordered unless the next outer loop is
** also ordered */
return nPriorSat;
}
if( OptimizationDisabled(db, SQLITE_OrderByIdxJoin) ){
/* Only look at the outer-most loop if the OrderByIdxJoin
** optimization is disabled */
return nPriorSat;
}
outerObUnique = (p->aLevel[p->i-1].plan.wsFlags & WHERE_OB_UNIQUE)!=0;
}
pOrderBy = p->pOrderBy;
assert( pOrderBy!=0 );
if( pIdx->bUnordered ){
/* Hash indices (indicated by the "unordered" tag on sqlite_stat1) cannot
** be used for sorting */
return nPriorSat;
|
> | | > > |
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int outerObUnique; /* Outer loops generate different values in
** every row for the ORDER BY columns */
if( p->i==0 ){
nPriorSat = 0;
outerObUnique = 1;
}else{
u32 wsFlags = p->aLevel[p->i-1].plan.wsFlags;
nPriorSat = p->aLevel[p->i-1].plan.nOBSat;
if( (wsFlags & WHERE_ORDERED)==0 ){
/* This loop cannot be ordered unless the next outer loop is
** also ordered */
return nPriorSat;
}
if( OptimizationDisabled(db, SQLITE_OrderByIdxJoin) ){
/* Only look at the outer-most loop if the OrderByIdxJoin
** optimization is disabled */
return nPriorSat;
}
testcase( wsFlags & WHERE_OB_UNIQUE );
testcase( wsFlags & WHERE_ALL_UNIQUE );
outerObUnique = (wsFlags & (WHERE_OB_UNIQUE|WHERE_ALL_UNIQUE))!=0;
}
pOrderBy = p->pOrderBy;
assert( pOrderBy!=0 );
if( pIdx->bUnordered ){
/* Hash indices (indicated by the "unordered" tag on sqlite_stat1) cannot
** be used for sorting */
return nPriorSat;
|