Teach the system how to use hashing for UNION. (INTERSECT/EXCEPT will follow,

[postgresql] / src / backend / optimizer / util / pathnode.c

diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c
index ad3c10ac27b5041c434ebea571067bedf10afeeb..655443e9efe03872fa51249005dad923d141e4ba 100644 (file)
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/optimizer/util/pathnode.c,v 1.144 2008/08/02 21:32:00 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/optimizer/util/pathnode.c,v 1.145 2008/08/07 01:11:50 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -24,7 +24,6 @@
 #include "optimizer/paths.h"
 #include "optimizer/tlist.h"
 #include "parser/parse_expr.h"
-#include "parser/parse_oper.h"
 #include "parser/parsetree.h"
 #include "utils/selfuncs.h"
 #include "utils/lsyscache.h"
@@ -1003,12 +1002,6 @@ query_is_distinct_for(Query *query, List *colnos, List *opids)
        /*
         * UNION, INTERSECT, EXCEPT guarantee uniqueness of the whole output row,
         * except with ALL.
-        *
-        * XXX this code knows that prepunion.c will adopt the default sort/group
-        * operators for each column datatype to determine uniqueness.  It'd
-        * probably be better if these operators were chosen at parse time and
-        * stored into the parsetree, instead of leaving bits of the planner to
-        * decide semantics.
         */
        if (query->setOperations)
        {
@@ -1019,24 +1012,26 @@ query_is_distinct_for(Query *query, List *colnos, List *opids)
 
                if (!topop->all)
                {
+                       ListCell   *lg;
+
                        /* We're good if all the nonjunk output columns are in colnos */
+                       lg = list_head(topop->groupClauses);
                        foreach(l, query->targetList)
                        {
                                TargetEntry *tle = (TargetEntry *) lfirst(l);
-                               Oid             tle_eq_opr;
+                               SortGroupClause *sgc;
 
                                if (tle->resjunk)
                                        continue;       /* ignore resjunk columns */
 
+                               /* non-resjunk columns should have grouping clauses */
+                               Assert(lg != NULL);
+                               sgc = (SortGroupClause *) lfirst(lg);
+                               lg = lnext(lg);
+
                                opid = distinct_col_search(tle->resno, colnos, opids);
-                               if (!OidIsValid(opid))
-                                       break;          /* exit early if no match */
-                               /* check for compatible semantics */
-                               get_sort_group_operators(exprType((Node *) tle->expr),
-                                                                                false, false, false,
-                                                                                NULL, &tle_eq_opr, NULL);
-                               if (!OidIsValid(tle_eq_opr) ||
-                                       !equality_ops_are_compatible(opid, tle_eq_opr))
+                               if (!OidIsValid(opid) ||
+                                       !equality_ops_are_compatible(opid, sgc->eqop))
                                        break;          /* exit early if no match */
                        }
                        if (l == NULL)          /* had matches for all? */