Dept of second thoughts: let's make sure that get_index_stats_hook is only

applied to expression indexes, not to plain relations.  The original coding
in btcostestimate conflated the two cases, but it's not hard to use
get_relation_stats_hook instead when we're looking to the underlying relation.

diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index e2336ea..fc9853a 100644 (file)
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -15,7 +15,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.254 2008/09/28 19:51:40 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.255 2008/09/28 20:42:12 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -5777,40 +5777,63 @@ btcostestimate(PG_FUNCTION_ARGS)
        if (found_saop)
                PG_RETURN_VOID();
 
+       MemSet(&vardata, 0, sizeof(vardata));
+
        if (index->indexkeys[0] != 0)
        {
                /* Simple variable --- look to stats for the underlying table */
-               relid = getrelid(index->rel->relid, root->parse->rtable);
+               RangeTblEntry *rte = planner_rt_fetch(index->rel->relid, root);
+
+               Assert(rte->rtekind == RTE_RELATION);
+               relid = rte->relid;
                Assert(relid != InvalidOid);
                colnum = index->indexkeys[0];
+
+               if (get_relation_stats_hook &&
+                       (*get_relation_stats_hook) (root, rte, colnum, &vardata))
+               {
+                       /*
+                        * The hook took control of acquiring a stats tuple.  If it did
+                        * supply a tuple, it'd better have supplied a freefunc.
+                        */
+                       if (HeapTupleIsValid(vardata.statsTuple) &&
+                               !vardata.freefunc)
+                               elog(ERROR, "no function provided to release variable stats with");
+               }
+               else
+               {
+                       vardata.statsTuple = SearchSysCache(STATRELATT,
+                                                                                               ObjectIdGetDatum(relid),
+                                                                                               Int16GetDatum(colnum),
+                                                                                               0, 0);
+                       vardata.freefunc = ReleaseSysCache;
+               }
        }
        else
        {
                /* Expression --- maybe there are stats for the index itself */
                relid = index->indexoid;
                colnum = 1;
-       }
-
-       MemSet(&vardata, 0, sizeof(vardata));
 
-       if (get_index_stats_hook &&
-               (*get_index_stats_hook) (root, relid, colnum, &vardata))
-       {
-               /*
-                * The hook took control of acquiring a stats tuple.  If it did supply
-                * a tuple, it'd better have supplied a freefunc.
-                */
-               if (HeapTupleIsValid(vardata.statsTuple) &&
-                       !vardata.freefunc)
-                       elog(ERROR, "no function provided to release variable stats with");
-       }
-       else
-       {
-               vardata.statsTuple = SearchSysCache(STATRELATT,
-                                                                                       ObjectIdGetDatum(relid),
-                                                                                       Int16GetDatum(colnum),
-                                                                                       0, 0);
-               vardata.freefunc = ReleaseSysCache;
+               if (get_index_stats_hook &&
+                       (*get_index_stats_hook) (root, relid, colnum, &vardata))
+               {
+                       /*
+                        * The hook took control of acquiring a stats tuple.  If it did
+                        * supply a tuple, it'd better have supplied a freefunc.
+                        */
+                       if (HeapTupleIsValid(vardata.statsTuple) &&
+                               !vardata.freefunc)
+                               elog(ERROR, "no function provided to release variable stats with");
+               }
+               else
+               {
+                       vardata.statsTuple = SearchSysCache(STATRELATT,
+                                                                                               ObjectIdGetDatum(relid),
+                                                                                               Int16GetDatum(colnum),
+                                                                                               0, 0);
+                       vardata.freefunc = ReleaseSysCache;
+               }
        }
 
        if (HeapTupleIsValid(vardata.statsTuple))