First phase of plan-invalidation project: create a plan cache management

module and teach PREPARE and protocol-level prepared statements to use it.
In service of this, rearrange utility-statement processing so that parse
analysis does not assume table schemas can't change before execution for
utility statements (necessary because we don't attempt to re-acquire locks
for utility statements when reusing a stored plan).  This requires some
refactoring of the ProcessUtility API, but it ends up cleaner anyway,
for instance we can get rid of the QueryContext global.

Still to do: fix up SPI and related code to use the plan cache; I'm tempted to
try to make SQL functions use it too.  Also, there are at least some aspects
of system state that we want to ensure remain the same during a replan as in
the original processing; search_path certainly ought to behave that way for
instance, and perhaps there are others.

src/include/commands/cluster.h

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994-5, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/commands/cluster.h,v 1.31 2007/01/05 22:19:53 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/commands/cluster.h,v 1.32 2007/03/13 00:33:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -17,7 +17,7 @@
 #include "utils/rel.h"
 
 
-extern void cluster(ClusterStmt *stmt);
+extern void cluster(ClusterStmt *stmt, bool isTopLevel);
 
 extern void check_index_is_clusterable(Relation OldHeap, Oid indexOid,
 						   bool recheck);

src/include/commands/copy.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/copy.h,v 1.29 2007/01/05 22:19:53 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/commands/copy.h,v 1.30 2007/03/13 00:33:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -18,7 +18,7 @@
 #include "tcop/dest.h"
 
 
-extern uint64 DoCopy(const CopyStmt *stmt);
+extern uint64 DoCopy(const CopyStmt *stmt, const char *queryString);
 
 extern DestReceiver *CreateCopyDestReceiver(void);
 

src/include/commands/defrem.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/defrem.h,v 1.80 2007/01/23 05:07:18 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/commands/defrem.h,v 1.81 2007/03/13 00:33:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -25,7 +25,6 @@ extern void DefineIndex(RangeVar *heapRelation,
 			char *tableSpaceName,
 			List *attributeList,
 			Expr *predicate,
-			List *rangetable,
 			List *options,
 			bool unique,
 			bool primary,

src/include/commands/explain.h

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994-5, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/commands/explain.h,v 1.29 2007/01/05 22:19:53 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/commands/explain.h,v 1.30 2007/03/13 00:33:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -16,11 +16,16 @@
 #include "executor/executor.h"
 
 
-extern void ExplainQuery(ExplainStmt *stmt, ParamListInfo params,
-			 DestReceiver *dest);
+extern void ExplainQuery(ExplainStmt *stmt, const char *queryString,
+						 ParamListInfo params, DestReceiver *dest);
 
 extern TupleDesc ExplainResultDesc(ExplainStmt *stmt);
 
+extern void ExplainOneUtility(Node *utilityStmt, ExplainStmt *stmt,
+							  const char *queryString,
+							  ParamListInfo params,
+							  TupOutputState *tstate);
+
 extern void ExplainOnePlan(QueryDesc *queryDesc, ExplainStmt *stmt,
 			   TupOutputState *tstate);
 

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 1.21 2007/02/20 17:32:17 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/commands/portalcmds.h,v 1.22 2007/03/13 00:33:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -18,7 +18,8 @@
 #include "utils/portal.h"
 
 
-extern void PerformCursorOpen(DeclareCursorStmt *stmt, ParamListInfo params);
+extern void PerformCursorOpen(DeclareCursorStmt *stmt, ParamListInfo params,
+							  const char *queryString, bool isTopLevel);
 
 extern void PerformPortalFetch(FetchStmt *stmt, DestReceiver *dest,
 				   char *completionTag);

src/include/commands/prepare.h

@@ -6,7 +6,7 @@
  *
  * Copyright (c) 2002-2007, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/include/commands/prepare.h,v 1.24 2007/02/20 17:32:17 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/commands/prepare.h,v 1.25 2007/03/13 00:33:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -14,58 +14,49 @@
 #define PREPARE_H
 
 #include "executor/executor.h"
+#include "utils/plancache.h"
 #include "utils/timestamp.h"
 
 /*
- * The data structure representing a prepared statement
+ * The data structure representing a prepared statement.  This is now just
+ * a thin veneer over a plancache entry --- the main addition is that of
+ * a name.
  *
- * A prepared statement might be fully planned, or only parsed-and-rewritten.
- * If fully planned, stmt_list contains PlannedStmts and/or utility statements;
- * if not, it contains Query nodes.
- *
- * Note: all subsidiary storage lives in the context denoted by the context
- * field.  However, the string referenced by commandTag is not subsidiary
- * storage; it is assumed to be a compile-time-constant string.  As with
- * portals, commandTag shall be NULL if and only if the original query string
- * (before rewriting) was an empty string.
+ * Note: all subsidiary storage lives in the referenced plancache entry.
  */
 typedef struct
 {
 	/* dynahash.c requires key to be first field */
 	char		stmt_name[NAMEDATALEN];
-	char	   *query_string;	/* text of query, or NULL */
-	const char *commandTag;		/* command tag (a constant!), or NULL */
-	List	   *stmt_list;		/* list of statement or Query nodes */
-	List	   *argtype_list;	/* list of parameter type OIDs */
-	bool		fully_planned;	/* what is in stmt_list, exactly? */
+	CachedPlanSource *plansource;	/* the actual cached plan */
 	bool		from_sql;		/* prepared via SQL, not FE/BE protocol? */
 	TimestampTz prepare_time;	/* the time when the stmt was prepared */
-	MemoryContext context;		/* context containing this query */
 } PreparedStatement;
 
 
 /* Utility statements PREPARE, EXECUTE, DEALLOCATE, EXPLAIN EXECUTE */
-extern void PrepareQuery(PrepareStmt *stmt);
-extern void ExecuteQuery(ExecuteStmt *stmt, ParamListInfo params,
+extern void PrepareQuery(PrepareStmt *stmt, const char *queryString);
+extern void ExecuteQuery(ExecuteStmt *stmt, const char *queryString,
+			 ParamListInfo params,
 			 DestReceiver *dest, char *completionTag);
 extern void DeallocateQuery(DeallocateStmt *stmt);
-extern void ExplainExecuteQuery(ExplainStmt *stmt, ParamListInfo params,
-					TupOutputState *tstate);
+extern void ExplainExecuteQuery(ExecuteStmt *execstmt, ExplainStmt *stmt,
+								const char *queryString,
+								ParamListInfo params, TupOutputState *tstate);
 
 /* Low-level access to stored prepared statements */
 extern void StorePreparedStatement(const char *stmt_name,
+					   Node *raw_parse_tree,
 					   const char *query_string,
 					   const char *commandTag,
+					   Oid *param_types,
+					   int num_params,
 					   List *stmt_list,
-					   List *argtype_list,
-					   bool fully_planned,
 					   bool from_sql);
 extern PreparedStatement *FetchPreparedStatement(const char *stmt_name,
 					   bool throwError);
 extern void DropPreparedStatement(const char *stmt_name, bool showError);
-extern List *FetchPreparedStatementParams(const char *stmt_name);
 extern TupleDesc FetchPreparedStatementResultDesc(PreparedStatement *stmt);
-extern bool PreparedStatementReturnsTuples(PreparedStatement *stmt);
 extern List *FetchPreparedStatementTargetList(PreparedStatement *stmt);
 
 #endif   /* PREPARE_H */

src/include/commands/schemacmds.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/schemacmds.h,v 1.15 2007/01/05 22:19:54 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/commands/schemacmds.h,v 1.16 2007/03/13 00:33:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -17,7 +17,8 @@
 
 #include "nodes/parsenodes.h"
 
-extern void CreateSchemaCommand(CreateSchemaStmt *parsetree);
+extern void CreateSchemaCommand(CreateSchemaStmt *parsetree,
+								const char *queryString);
 
 extern void RemoveSchema(List *names, DropBehavior behavior, bool missing_ok);
 extern void RemoveSchemaById(Oid schemaOid);

src/include/commands/vacuum.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/vacuum.h,v 1.69 2007/01/05 22:19:54 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/commands/vacuum.h,v 1.70 2007/03/13 00:33:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -110,7 +110,7 @@ extern int	vacuum_freeze_min_age;
 
 
 /* in commands/vacuum.c */
-extern void vacuum(VacuumStmt *vacstmt, List *relids);
+extern void vacuum(VacuumStmt *vacstmt, List *relids, bool isTopLevel);
 extern void vac_open_indexes(Relation relation, LOCKMODE lockmode,
 				 int *nindexes, Relation **Irel);
 extern void vac_close_indexes(int nindexes, Relation *Irel, LOCKMODE lockmode);

src/include/commands/view.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/view.h,v 1.24 2007/01/05 22:19:54 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/commands/view.h,v 1.25 2007/03/13 00:33:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -16,7 +16,7 @@
 
 #include "nodes/parsenodes.h"
 
-extern void DefineView(RangeVar *view, Query *view_parse, bool replace);
+extern void DefineView(ViewStmt *stmt, const char *queryString);
 extern void RemoveView(const RangeVar *view, DropBehavior behavior);
 
 #endif   /* VIEW_H */