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, 20 insertions, 8 deletions

diff --git a/src/backend/rewrite/rewriteManip.c b/src/backend/rewrite/rewriteManip.c
index c8652ff5f2d..b5d82dd0e7f 100644
--- a/src/backend/rewrite/rewriteManip.c
+++ b/src/backend/rewrite/rewriteManip.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/rewrite/rewriteManip.c,v 1.113 2008/09/01 20:42:45 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/rewrite/rewriteManip.c,v 1.114 2008/10/04 21:56:54 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -183,13 +183,13 @@ bool
 checkExprHasSubLink(Node *node)
 {
 	/*
-	 * If a Query is passed, examine it --- but we need not recurse into
-	 * sub-Queries.
+	 * If a Query is passed, examine it --- but we should not recurse into
+	 * sub-Queries that are in its rangetable or CTE list.
 	 */
 	return query_or_expression_tree_walker(node,
 										   checkExprHasSubLink_walker,
 										   NULL,
-										   QTW_IGNORE_RT_SUBQUERIES);
+										   QTW_IGNORE_RC_SUBQUERIES);
 }
 
 static bool
@@ -543,7 +543,7 @@ adjust_relid_set(Relids relids, int oldrelid, int newrelid)
  * that sublink are not affected, only outer references to vars that belong
  * to the expression's original query level or parents thereof.
  *
- * Aggref nodes are adjusted similarly.
+ * Likewise for other nodes containing levelsup fields, such as Aggref.
  *
  * NOTE: although this has the form of a walker, we cheat and modify the
  * Var nodes in-place.	The given expression tree should have been copied
@@ -585,6 +585,17 @@ IncrementVarSublevelsUp_walker(Node *node,
 			agg->agglevelsup += context->delta_sublevels_up;
 		/* fall through to recurse into argument */
 	}
+	if (IsA(node, RangeTblEntry))
+	{
+		RangeTblEntry *rte = (RangeTblEntry *) node;
+
+		if (rte->rtekind == RTE_CTE)
+		{
+			if (rte->ctelevelsup >= context->min_sublevels_up)
+				rte->ctelevelsup += context->delta_sublevels_up;
+		}
+		return false;			/* allow range_table_walker to continue */
+	}
 	if (IsA(node, Query))
 	{
 		/* Recurse into subselects */
@@ -593,7 +604,8 @@ IncrementVarSublevelsUp_walker(Node *node,
 		context->min_sublevels_up++;
 		result = query_tree_walker((Query *) node,
 								   IncrementVarSublevelsUp_walker,
-								   (void *) context, 0);
+								   (void *) context,
+								   QTW_EXAMINE_RTES);
 		context->min_sublevels_up--;
 		return result;
 	}
@@ -617,7 +629,7 @@ IncrementVarSublevelsUp(Node *node, int delta_sublevels_up,
 	query_or_expression_tree_walker(node,
 									IncrementVarSublevelsUp_walker,
 									(void *) &context,
-									0);
+									QTW_EXAMINE_RTES);
 }
 
 /*
@@ -636,7 +648,7 @@ IncrementVarSublevelsUp_rtable(List *rtable, int delta_sublevels_up,
 	range_table_walker(rtable,
 					   IncrementVarSublevelsUp_walker,
 					   (void *) &context,
-					   0);
+					   QTW_EXAMINE_RTES);
 }