Some further performance tweaks for planning large inheritance trees that

are mostly excluded by constraints: do the CE test a bit earlier to save
some adjust_appendrel_attrs() work on excluded children, and arrange to
use array indexing rather than rt_fetch() to fetch RTEs in the main body
of the planner.  The latter is something I'd wanted to do for awhile anyway,
but seeing list_nth_cell() as 35% of the runtime gets one's attention.

1 files changed, 19 insertions, 1 deletions

diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index 2c26d121ef4..57af937830f 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.140 2007/04/06 22:33:43 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.141 2007/04/21 21:01:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -109,6 +109,14 @@ typedef struct PlannerInfo
 	int			simple_rel_array_size;	/* allocated size of array */
 
 	/*
+	 * simple_rte_array is the same length as simple_rel_array and holds
+	 * pointers to the associated rangetable entries.  This lets us avoid
+	 * rt_fetch(), which can be a bit slow once large inheritance sets have
+	 * been expanded.
+	 */
+	RangeTblEntry **simple_rte_array;			/* rangetable as an array */
+
+	/*
 	 * join_rel_list is a list of all join-relation RelOptInfos we have
 	 * considered in this planning run.  For small problems we just scan the
 	 * list to do lookups, but when there are many join relations we build a
@@ -167,6 +175,16 @@ typedef struct PlannerInfo
 } PlannerInfo;
 
 
+/*
+ * In places where it's known that simple_rte_array[] must have been prepared
+ * already, we just index into it to fetch RTEs.  In code that might be
+ * executed before or after entering query_planner(), use this macro.
+ */
+#define planner_rt_fetch(rti, root) \
+	((root)->simple_rte_array ? (root)->simple_rte_array[rti] : \
+	 rt_fetch(rti, (root)->parse->rtable))
+
+
 /*----------
  * RelOptInfo
  *		Per-relation information for planning/optimization