Make set_function_size_estimates() marginally smarter: per original

comment, it can at least test whether the expression returns set.

diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 24af7afe799479e2a9807f65e85da355adb4d8a1..bb506678ce400354436d083e42f5aba8ef38522b 100644 (file)
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -49,7 +49,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.147 2005/08/27 22:37:00 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.148 2005/10/05 17:19:19 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1898,17 +1898,23 @@ join_in_selectivity(JoinPath *path, PlannerInfo *root)
 void
 set_function_size_estimates(PlannerInfo *root, RelOptInfo *rel)
 {
+       RangeTblEntry *rte;
+
        /* Should only be applied to base relations that are functions */
        Assert(rel->relid > 0);
-       Assert(rel->rtekind == RTE_FUNCTION);
+       rte = rt_fetch(rel->relid, root->parse->rtable);
+       Assert(rte->rtekind == RTE_FUNCTION);
 
        /*
         * Estimate number of rows the function itself will return.
         *
-        * XXX no idea how to do this yet; but should at least check whether
+        * XXX no idea how to do this yet; but we can at least check whether
         * function returns set or not...
         */
-       rel->tuples = 1000;
+       if (expression_returns_set(rte->funcexpr))
+               rel->tuples = 1000;
+       else
+               rel->tuples = 1;
 
        /* Now estimate number of output rows, etc */
        set_baserel_size_estimates(root, rel);