Implement SQL-standard WITH clauses, including WITH RECURSIVE.

There are some unimplemented aspects: recursive queries must use UNION ALL
(should allow UNION too), and we don't have SEARCH or CYCLE clauses.
These might or might not get done for 8.4, but even without them it's a
pretty useful feature.

There are also a couple of small loose ends and definitional quibbles,
which I'll send a memo about to pgsql-hackers shortly.  But let's land
the patch now so we can get on with other development.

Yoshiyuki Asaba, with lots of help from Tatsuo Ishii and Tom Lane

1 files changed, 12 insertions, 24 deletions

diff --git a/src/backend/optimizer/path/clausesel.c b/src/backend/optimizer/path/clausesel.c
index 9ffdc32e775..e3e4e9f02c0 100644
--- a/src/backend/optimizer/path/clausesel.c
+++ b/src/backend/optimizer/path/clausesel.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/path/clausesel.c,v 1.93 2008/08/22 00:16:03 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/path/clausesel.c,v 1.94 2008/10/04 21:56:53 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -550,29 +550,17 @@ clause_selectivity(PlannerInfo *root,
 		if (var->varlevelsup == 0 &&
 			(varRelid == 0 || varRelid == (int) var->varno))
 		{
-			RangeTblEntry *rte = planner_rt_fetch(var->varno, root);
-
-			if (rte->rtekind == RTE_SUBQUERY)
-			{
-				/*
-				 * XXX not smart about subquery references... any way to do
-				 * better than default?
-				 */
-			}
-			else
-			{
-				/*
-				 * A Var at the top of a clause must be a bool Var. This is
-				 * equivalent to the clause reln.attribute = 't', so we
-				 * compute the selectivity as if that is what we have.
-				 */
-				s1 = restriction_selectivity(root,
-											 BooleanEqualOperator,
-											 list_make2(var,
-														makeBoolConst(true,
-																	  false)),
-											 varRelid);
-			}
+			/*
+			 * A Var at the top of a clause must be a bool Var. This is
+			 * equivalent to the clause reln.attribute = 't', so we
+			 * compute the selectivity as if that is what we have.
+			 */
+			s1 = restriction_selectivity(root,
+										 BooleanEqualOperator,
+										 list_make2(var,
+													makeBoolConst(true,
+																  false)),
+										 varRelid);
 		}
 	}
 	else if (IsA(clause, Const))