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 e2336ea4f21c0cacccb10b29b7e8f8265037f854..fc9853a43a938591d30841eb8fb664b06b66aa81 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))