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, 14 insertions, 4 deletions

diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index c66bc05a749..9cb4370c854 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.159 2008/09/09 18:58:08 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.160 2008/10/04 21:56:55 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -104,6 +104,8 @@ typedef struct PlannerInfo
 
 	Index		query_level;	/* 1 at the outermost Query */
 
+	struct PlannerInfo *parent_root; /* NULL at outermost Query */
+
 	/*
 	 * simple_rel_array holds pointers to "base rels" and "other rels" (see
 	 * comments for RelOptInfo for more info).	It is indexed by rangetable
@@ -138,7 +140,9 @@ typedef struct PlannerInfo
 
 	List	   *returningLists; /* list of lists of TargetEntry, or NIL */
 
-	List	   *init_plans;		/* init subplans for query */
+	List	   *init_plans;		/* init SubPlans for query */
+
+	List	   *cte_plan_ids;	/* per-CTE-item list of subplan IDs */
 
 	List	   *eq_classes;		/* list of active EquivalenceClasses */
 
@@ -178,6 +182,11 @@ typedef struct PlannerInfo
 	bool		hasHavingQual;	/* true if havingQual was non-null */
 	bool		hasPseudoConstantQuals; /* true if any RestrictInfo has
 										 * pseudoconstant = true */
+	bool		hasRecursion;	/* true if planning a recursive WITH item */
+
+	/* These fields are used only when hasRecursion is true: */
+	int			wt_param_id;			/* PARAM_EXEC ID for the work table */
+	struct Plan *non_recursive_plan;	/* plan for non-recursive term */
 } PlannerInfo;
 
 
@@ -542,8 +551,9 @@ typedef struct PathKey
 } PathKey;
 
 /*
- * Type "Path" is used as-is for sequential-scan paths.  For other
- * path types it is the first component of a larger struct.
+ * Type "Path" is used as-is for sequential-scan paths, as well as some other
+ * simple plan types that we don't need any extra information in the path for.
+ * For other path types it is the first component of a larger struct.
  *
  * Note: "pathtype" is the NodeTag of the Plan node we could build from this
  * Path.  It is partially redundant with the Path's NodeTag, but allows us