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| author | drh <> | 2025-05-31 16:17:14 +0000 |
|---|---|---|
| committer | drh <> | 2025-05-31 16:17:14 +0000 |
| commit | 52486939249c1104572b8c45563de19f600e7f96 (patch) | |
| tree | 81be46aa39fd2207b61a2f05e1fe261c59b61b46 /src | |
| parent | 1ff4233f903d0fae532a6bda64ccbb7a319e13db (diff) | |
| download | sqlite-52486939249c1104572b8c45563de19f600e7f96.tar.gz sqlite-52486939249c1104572b8c45563de19f600e7f96.zip | |
Relax query flattener constraint (3b) and thereby allow flattening the RHS of
a LEFT JOIN even if the RHS contains a virtual table. This was previously
disallowed by [9dbae1df75219e2a] as a performance optimization. It
turns out that the constraint causes performance issues, and we do not have
a record of any performance issue that it solves.
FossilOrigin-Name: 1ddaa92057e550ea281d45d9860eafe69399224725548a93dd91c47a34e52152
Diffstat (limited to 'src')
| -rw-r--r-- | src/select.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/src/select.c b/src/select.c index a8af934e4..8eaf5e2b6 100644 --- a/src/select.c +++ b/src/select.c @@ -4245,9 +4245,9 @@ static int compoundHasDifferentAffinities(Select *p){ ** from 2015-02-09.) ** ** (3) If the subquery is the right operand of a LEFT JOIN then -** (3a) the subquery may not be a join and -** (3b) the FROM clause of the subquery may not contain a virtual -** table and +** (3a) the subquery may not be a join +** (**) Was (3b): "the FROM clause of the subquery may not contain +** a virtual table" ** (**) Was: "The outer query may not have a GROUP BY." This case ** is now managed correctly ** (3d) the outer query may not be DISTINCT. @@ -4463,7 +4463,7 @@ static int flattenSubquery( */ if( (pSubitem->fg.jointype & (JT_OUTER|JT_LTORJ))!=0 ){ if( pSubSrc->nSrc>1 /* (3a) */ - || IsVirtual(pSubSrc->a[0].pSTab) /* (3b) */ + /**** || IsVirtual(pSubSrc->a[0].pSTab) (3b)-omitted */ || (p->selFlags & SF_Distinct)!=0 /* (3d) */ || (pSubitem->fg.jointype & JT_RIGHT)!=0 /* (26) */ ){ |