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authorTom Lane <tgl@sss.pgh.pa.us>2017-09-17 15:28:51 -0400
committerTom Lane <tgl@sss.pgh.pa.us>2017-09-17 15:28:51 -0400
commit86e4ebb9af7ed07f11410d568e0fd72427f3b0e3 (patch)
tree4d2b60c2d050d10a34265c71d2161d056ed346f3
parentc0d21bdb86b1eadd25ae56f07729aa53e1ca64c0 (diff)
downloadpostgresql-86e4ebb9af7ed07f11410d568e0fd72427f3b0e3.tar.gz
postgresql-86e4ebb9af7ed07f11410d568e0fd72427f3b0e3.zip
Allow rel_is_distinct_for() to look through RelabelType below OpExpr.
This lets it do the right thing for, eg, varchar columns. Back-patch to 9.5 where this logic appeared. David Rowley, per report from Kim Rose Carlsen Discussion: https://postgr.es/m/VI1PR05MB17091F9A9876528055D6A827C76D0@VI1PR05MB1709.eurprd05.prod.outlook.com
-rw-r--r--src/backend/optimizer/plan/analyzejoins.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c
index e28a8dc533e..614fd293ed1 100644
--- a/src/backend/optimizer/plan/analyzejoins.c
+++ b/src/backend/optimizer/plan/analyzejoins.c
@@ -618,6 +618,14 @@ rel_is_distinct_for(PlannerInfo *root, RelOptInfo *rel, List *clause_list)
var = (Var *) get_leftop(rinfo->clause);
/*
+ * We may ignore any RelabelType node above the operand. (There
+ * won't be more than one, since eval_const_expressions() has been
+ * applied already.)
+ */
+ if (var && IsA(var, RelabelType))
+ var = (Var *) ((RelabelType *) var)->arg;
+
+ /*
* If inner side isn't a Var referencing a subquery output column,
* this clause doesn't help us.
*/