Salvage a little bit of work from a failed patch: simplify and speed up

set_rel_width().  The code had been catering for the possibility of different
varnos in the relation targetlist, but this is impossible for a base relation
(and if it were possible, putting all the widths in the same RelOptInfo would
be wrong anyway).

diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 7bfc66cac3a82b6da7022618cfe4b7e19e9e7a5c..fa580cf14e6796383e7dd586fe81cc914dc1d095 100644 (file)
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -54,7 +54,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.198 2008/10/04 21:56:53 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.199 2008/10/17 20:27:24 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2608,24 +2608,14 @@ set_cte_size_estimates(PlannerInfo *root, RelOptInfo *rel, Plan *cteplan)
 static void
 set_rel_width(PlannerInfo *root, RelOptInfo *rel)
 {
+       Oid                     reloid = planner_rt_fetch(rel->relid, root)->relid;
        int32           tuple_width = 0;
        ListCell   *tllist;
-       Oid                     rel_reloid;
-
-       /*
-        * Usually (perhaps always), all the Vars have the same reloid, so we can
-        * save some redundant list-searching by doing getrelid just once.
-        */
-       if (rel->relid > 0)
-               rel_reloid = getrelid(rel->relid, root->parse->rtable);
-       else
-               rel_reloid = InvalidOid;        /* probably can't happen */
 
        foreach(tllist, rel->reltargetlist)
        {
                Var                *var = (Var *) lfirst(tllist);
                int                     ndx;
-               Oid                     var_reloid;
                int32           item_width;
 
                /* For now, punt on whole-row child Vars */
@@ -2635,6 +2625,10 @@ set_rel_width(PlannerInfo *root, RelOptInfo *rel)
                        continue;
                }
 
+               Assert(var->varno == rel->relid);
+               Assert(var->varattno >= rel->min_attr);
+               Assert(var->varattno <= rel->max_attr);
+
                ndx = var->varattno - rel->min_attr;
 
                /*
@@ -2646,14 +2640,9 @@ set_rel_width(PlannerInfo *root, RelOptInfo *rel)
                        continue;
                }
 
-               if (var->varno == rel->relid)
-                       var_reloid = rel_reloid;
-               else
-                       var_reloid = getrelid(var->varno, root->parse->rtable);
-
-               if (var_reloid != InvalidOid)
+               if (reloid != InvalidOid)
                {
-                       item_width = get_attavgwidth(var_reloid, var->varattno);
+                       item_width = get_attavgwidth(reloid, var->varattno);
                        if (item_width > 0)
                        {
                                rel->attr_widths[ndx] = item_width;