Modify processing of DECLARE CURSOR and EXPLAIN so that they can resolve the

types of unspecified parameters when submitted via extended query protocol.
This worked in 8.2 but I had broken it during plancache changes.  DECLARE
CURSOR is now treated almost exactly like a plain SELECT through parse
analysis, rewrite, and planning; only just before sending to the executor
do we divert it away to ProcessUtility.  This requires a special-case check
in a number of places, but practically all of them were already special-casing
SELECT INTO, so it's not too ugly.  (Maybe it would be a good idea to merge
the two by treating IntoClause as a form of utility statement?  Not going to
worry about that now, though.)  That approach doesn't work for EXPLAIN,
however, so for that I punted and used a klugy solution of running parse
analysis an extra time if under extended query protocol.

3 files changed, 20 insertions, 11 deletions

diff --git a/src/include/commands/portalcmds.h b/src/include/commands/portalcmds.h
index 3d774046136..66a2effc509 100644
--- a/src/include/commands/portalcmds.h
+++ b/src/include/commands/portalcmds.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/commands/portalcmds.h,v 1.22 2007/03/13 00:33:43 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/commands/portalcmds.h,v 1.23 2007/04/27 22:05:49 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -15,10 +15,11 @@
 #define PORTALCMDS_H
 
 #include "nodes/parsenodes.h"
+#include "nodes/plannodes.h"
 #include "utils/portal.h"
 
 
-extern void PerformCursorOpen(DeclareCursorStmt *stmt, ParamListInfo params,
+extern void PerformCursorOpen(PlannedStmt *stmt, ParamListInfo params,
 							  const char *queryString, bool isTopLevel);
 
 extern void PerformPortalFetch(FetchStmt *stmt, DestReceiver *dest,
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 09cb4ff5031..179d7a765db 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.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/parsenodes.h,v 1.347 2007/04/26 16:13:14 neilc Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.348 2007/04/27 22:05:49 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -82,9 +82,11 @@ typedef uint32 AclMode;			/* a bitmask of privilege bits */
  *
  *	  Utility statements (i.e. non-optimizable statements) have the
  *	  utilityStmt field set, and the Query itself is mostly dummy.
+ *	  DECLARE CURSOR is a special case: it is represented like a SELECT,
+ *	  but the original DeclareCursorStmt is stored in utilityStmt.
  *
  *	  Planning converts a Query tree into a Plan tree headed by a PlannedStmt
- *	  noded --- the Query structure is not used by the executor.
+ *	  node --- the Query structure is not used by the executor.
  */
 typedef struct Query
 {
@@ -96,13 +98,13 @@ typedef struct Query
 
 	bool		canSetTag;		/* do I set the command result tag? */
 
-	Node	   *utilityStmt;	/* non-null if this is a non-optimizable
-								 * statement */
+	Node	   *utilityStmt;	/* non-null if this is DECLARE CURSOR or a
+								 * non-optimizable statement */
 
 	int			resultRelation; /* rtable index of target relation for
 								 * INSERT/UPDATE/DELETE; 0 for SELECT */
 
-	IntoClause *into;			/* target for SELECT INTO / CREATE TABLE AS */
+	IntoClause *intoClause;		/* target for SELECT INTO / CREATE TABLE AS */
 
 	bool		hasAggs;		/* has aggregates in tlist or havingQual */
 	bool		hasSubLinks;	/* has subquery SubLink */
@@ -732,7 +734,7 @@ typedef struct SelectStmt
 	 */
 	List	   *distinctClause; /* NULL, list of DISTINCT ON exprs, or
 								 * lcons(NIL,NIL) for all (SELECT DISTINCT) */
-	IntoClause *into;			/* target for SELECT INTO / CREATE TABLE AS */
+	IntoClause *intoClause;		/* target for SELECT INTO / CREATE TABLE AS */
 	List	   *targetList;		/* the target list (of ResTarget) */
 	List	   *fromClause;		/* the FROM clause */
 	Node	   *whereClause;	/* WHERE qualification */
@@ -1427,6 +1429,10 @@ typedef struct CommentStmt
 
 /* ----------------------
  *		Declare Cursor Statement
+ *
+ * Note: the "query" field of DeclareCursorStmt is only used in the raw grammar
+ * output.  After parse analysis it's set to null, and the Query points to the
+ * DeclareCursorStmt, not vice versa.
  * ----------------------
  */
 #define CURSOR_OPT_BINARY		0x0001		/* BINARY */
@@ -1441,7 +1447,7 @@ typedef struct DeclareCursorStmt
 	NodeTag		type;
 	char	   *portalname;		/* name of the portal (cursor) */
 	int			options;		/* bitmask of options (see above) */
-	Node	   *query;			/* the SELECT query */
+	Node	   *query;			/* the raw SELECT query */
 } DeclareCursorStmt;
 
 /* ----------------------
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index aecfb519399..9d336e4b889 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.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/plannodes.h,v 1.93 2007/02/27 01:11:26 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/plannodes.h,v 1.94 2007/04/27 22:05:49 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -46,7 +46,9 @@ typedef struct PlannedStmt
 	/* rtable indexes of target relations for INSERT/UPDATE/DELETE */
 	List	   *resultRelations;	/* integer list of RT indexes, or NIL */
 
-	IntoClause *into;			/* target for SELECT INTO / CREATE TABLE AS */
+	Node	   *utilityStmt;	/* non-null if this is DECLARE CURSOR */
+
+	IntoClause *intoClause;		/* target for SELECT INTO / CREATE TABLE AS */
 
 	List	   *subplans;		/* Plan trees for SubPlan expressions */