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Fix adjust_semi_join to be more cautious about clauseless joins.

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It was reporting that these were fully indexed (hence cheap), when of
course they're the exact opposite of that.  I'm not certain if the case
would arise in practice, since a clauseless semijoin is hard to produce
in SQL, but if it did happen we'd make some dumb decisions.
This commit is contained in:
Tom Lane 2010-11-02 18:45:50 -04:00
parent 5ab15b521f
commit 55c3a7c0a5
1 changed files with 13 additions and 5 deletions
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18
src/backend/optimizer/path/costsize.c
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@ -2579,12 +2579,20 @@ adjust_semi_join(PlannerInfo *root, JoinPath *path, SpecialJoinInfo *sjinfo,
*/
if (indexed_join_quals)
{
List *nrclauses;
if (path->joinrestrictinfo != NIL)
{
List *nrclauses;
nrclauses = select_nonredundant_join_clauses(root,
path->joinrestrictinfo,
path->innerjoinpath);
*indexed_join_quals = (nrclauses == NIL);
nrclauses = select_nonredundant_join_clauses(root,
path->joinrestrictinfo,
path->innerjoinpath);
*indexed_join_quals = (nrclauses == NIL);
}
else
{
/* a clauseless join does NOT qualify */
*indexed_join_quals = false;
}
}
return true;