Fix oversight in construction of sort/unique plans for UniquePaths.

If the original IN operator is cross-type, for example int8 = int4,
we need to use int4 < int4 to sort the inner data and int4 = int4
to unique-ify it.  We got the first part of that right, but tried to
use the original IN operator for the equality checks.  Per bug #5472
from Vlad Romascanu.

Backpatch to 8.4, where the bug was introduced by the patch that unified
SortClause and GroupClause.  I was able to take out a whole lot of on-the-fly
calls of get_equality_op_for_ordering_op(), but failed to realize that
I needed to put one back in right here :-(

diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index a87c2b80fb2aa6c52384beab172969eb62a4018f..3d6f9f94faa2f050fbb4ab411ad10da5e695d449 100644 (file)
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.274 2010/03/28 22:59:32 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.275 2010/05/25 17:44:41 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -784,6 +784,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path)
        {
            Oid         in_oper = lfirst_oid(l);
            Oid         sortop;
+           Oid         eqop;
            TargetEntry *tle;
            SortGroupClause *sortcl;
 
@@ -791,13 +792,26 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path)
            if (!OidIsValid(sortop))    /* shouldn't happen */
                elog(ERROR, "could not find ordering operator for equality operator %u",
                     in_oper);
+
+           /*
+            * The Unique node will need equality operators.  Normally these
+            * are the same as the IN clause operators, but if those are
+            * cross-type operators then the equality operators are the ones
+            * for the IN clause operators' RHS datatype.
+            */
+           eqop = get_equality_op_for_ordering_op(sortop, NULL);
+           if (!OidIsValid(eqop))      /* shouldn't happen */
+               elog(ERROR, "could not find equality operator for ordering operator %u",
+                    sortop);
+
            tle = get_tle_by_resno(subplan->targetlist,
                                   groupColIdx[groupColPos]);
            Assert(tle != NULL);
+
            sortcl = makeNode(SortGroupClause);
            sortcl->tleSortGroupRef = assignSortGroupRef(tle,
                                                         subplan->targetlist);
-           sortcl->eqop = in_oper;
+           sortcl->eqop = eqop;
            sortcl->sortop = sortop;
            sortcl->nulls_first = false;
            sortList = lappend(sortList, sortcl);