4 files changed, 23 insertions, 8 deletions
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index 2f906c6a472..88e535dc9b9 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.116 2005/07/02 23:00:42 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.117 2005/07/23 21:05:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -516,6 +516,9 @@ typedef struct TidPath
  * AppendPath represents an Append plan, ie, successive execution of
  * several member plans.  Currently it is only used to handle expansion
  * of inheritance trees.
+ *
+ * Note: it is possible for "subpaths" to contain only one, or even no,
+ * elements.  These cases are optimized during create_append_plan.
  */
 typedef struct AppendPath
 {
@@ -524,10 +527,17 @@ typedef struct AppendPath
 } AppendPath;
 
 /*
- * ResultPath represents use of a Result plan node, either to compute a
- * variable-free targetlist or to gate execution of a subplan with a
- * one-time (variable-free) qual condition.  Note that in the former case
- * path.parent will be NULL; in the latter case it is copied from the subpath.
+ * ResultPath represents use of a Result plan node.  There are several
+ * applications for this:
+ *	* To compute a variable-free targetlist (a "SELECT expressions" query).
+ *	  In this case subpath and path.parent will both be NULL.  constantqual
+ *	  might or might not be empty ("SELECT expressions WHERE something").
+ *	* To gate execution of a subplan with a one-time (variable-free) qual
+ *	  condition.  path.parent is copied from the subpath.
+ *	* To substitute for a scan plan when we have proven that no rows in
+ *	  a table will satisfy the query.  subpath is NULL but path.parent
+ *	  references the not-to-be-scanned relation, and constantqual is
+ *	  a constant FALSE.
  *
  * Note that constantqual is a list of bare clauses, not RestrictInfos.
  */
diff --git a/src/include/optimizer/cost.h b/src/include/optimizer/cost.h
index 5b6d2824253..a6988e45991 100644
--- a/src/include/optimizer/cost.h
+++ b/src/include/optimizer/cost.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/cost.h,v 1.68 2005/06/05 22:32:58 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/cost.h,v 1.69 2005/07/23 21:05:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -49,6 +49,7 @@ extern bool enable_hashagg;
 extern bool enable_nestloop;
 extern bool enable_mergejoin;
 extern bool enable_hashjoin;
+extern bool enable_constraint_exclusion;
 
 extern double clamp_row_est(double nrows);
 extern void cost_seqscan(Path *path, PlannerInfo *root, RelOptInfo *baserel);
diff --git a/src/include/optimizer/plancat.h b/src/include/optimizer/plancat.h
index f8ecd36110d..8a4c1e4941e 100644
--- a/src/include/optimizer/plancat.h
+++ b/src/include/optimizer/plancat.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/plancat.h,v 1.36 2005/06/05 22:32:58 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/plancat.h,v 1.37 2005/07/23 21:05:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -19,6 +19,8 @@
 
 extern void get_relation_info(Oid relationObjectId, RelOptInfo *rel);
 
+extern List *get_relation_constraints(Oid relationObjectId, RelOptInfo *rel);
+
 extern List *build_physical_tlist(PlannerInfo *root, RelOptInfo *rel);
 
 extern List *find_inheritance_children(Oid inhparent);
diff --git a/src/include/optimizer/predtest.h b/src/include/optimizer/predtest.h
index cfa58f650a1..0fc0d0f4476 100644
--- a/src/include/optimizer/predtest.h
+++ b/src/include/optimizer/predtest.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/predtest.h,v 1.1 2005/06/10 22:25:37 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/predtest.h,v 1.2 2005/07/23 21:05:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -19,5 +19,7 @@
 
 extern bool predicate_implied_by(List *predicate_list,
 								 List *restrictinfo_list);
+extern bool predicate_refuted_by(List *predicate_list,
+								 List *restrictinfo_list);
 
 #endif   /* PREDTEST_H */