postgres.git / summary / log / commit / refs

commit    61d6dd0c03eb4da654f435097cd0bf1da11c3272
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Tue Nov 02 22:45:36 2010 +0000
First released in: 9.1.0, 8.4.6, 9.0.2

    Fix adjust_semi_join to be more cautious about clauseless joins.
    
    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.


 src/backend/optimizer/path/costsize.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 067cbca1254..16a5d0a3ca2 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -2897,12 +2897,20 @@ 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;


[parent: 71baff1786e0]