Include a pointer to the query's source text in QueryDesc structs. This is

practically free given prior 8.4 changes in plancache and portal management,
and it makes it a lot easier for ExecutorStart/Run/End hooks to get at the
query text.  Extracted from Itagaki Takahiro's pg_stat_statements patch,
with minor editorialization.

src/backend/commands/copy.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/copy.c,v 1.303 2009/01/01 17:23:37 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/copy.c,v 1.304 2009/01/02 20:42:00 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1054,7 +1054,8 @@ DoCopy(const CopyStmt *stmt, const char *queryString)
 		((DR_copy *) dest)->cstate = cstate;
 
 		/* Create a QueryDesc requesting no output */
-		cstate->queryDesc = CreateQueryDesc(plan, GetActiveSnapshot(),
+		cstate->queryDesc = CreateQueryDesc(plan, queryString,
+											GetActiveSnapshot(),
 											InvalidSnapshot,
 											dest, NULL, false);
 

src/backend/commands/explain.c

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994-5, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.183 2009/01/01 17:23:37 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.184 2009/01/02 20:42:00 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -172,7 +172,7 @@ ExplainOneQuery(Query *query, ExplainStmt *stmt, const char *queryString,
 		plan = pg_plan_query(query, 0, params);
 
 		/* run it (if needed) and produce output */
-		ExplainOnePlan(plan, params, stmt, tstate);
+		ExplainOnePlan(plan, stmt, queryString, params, tstate);
 	}
 }
 
@@ -218,8 +218,9 @@ ExplainOneUtility(Node *utilityStmt, ExplainStmt *stmt,
  * to call it.
  */
 void
-ExplainOnePlan(PlannedStmt *plannedstmt, ParamListInfo params,
-			   ExplainStmt *stmt, TupOutputState *tstate)
+ExplainOnePlan(PlannedStmt *plannedstmt, ExplainStmt *stmt,
+			   const char *queryString, ParamListInfo params,
+			   TupOutputState *tstate)
 {
 	QueryDesc  *queryDesc;
 	instr_time	starttime;
@@ -234,7 +235,7 @@ ExplainOnePlan(PlannedStmt *plannedstmt, ParamListInfo params,
 	PushUpdatedSnapshot(GetActiveSnapshot());
 
 	/* Create a QueryDesc requesting no output */
-	queryDesc = CreateQueryDesc(plannedstmt,
+	queryDesc = CreateQueryDesc(plannedstmt, queryString,
 								GetActiveSnapshot(), InvalidSnapshot,
 								None_Receiver, params,
 								stmt->analyze);

src/backend/commands/prepare.c

@@ -10,7 +10,7 @@
  * Copyright (c) 2002-2009, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/prepare.c,v 1.95 2009/01/01 17:23:39 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/prepare.c,v 1.96 2009/01/02 20:42:00 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -636,6 +636,9 @@ DropAllPreparedStatements(void)
 
 /*
  * Implements the 'EXPLAIN EXECUTE' utility statement.
+ *
+ * Note: the passed-in queryString is that of the EXPLAIN EXECUTE,
+ * not the original PREPARE; we get the latter string from the plancache.
  */
 void
 ExplainExecuteQuery(ExecuteStmt *execstmt, ExplainStmt *stmt,
@@ -643,6 +646,7 @@ ExplainExecuteQuery(ExecuteStmt *execstmt, ExplainStmt *stmt,
 					ParamListInfo params, TupOutputState *tstate)
 {
 	PreparedStatement *entry;
+	const char *query_string;
 	CachedPlan *cplan;
 	List	   *plan_list;
 	ListCell   *p;
@@ -659,6 +663,8 @@ ExplainExecuteQuery(ExecuteStmt *execstmt, ExplainStmt *stmt,
 	if (!entry->plansource->fixed_result)
 		elog(ERROR, "EXPLAIN EXECUTE does not support variable-result cached plans");
 
+	query_string = entry->plansource->query_string;
+
 	/* Replan if needed, and acquire a transient refcount */
 	cplan = RevalidateCachedPlan(entry->plansource, true);
 
@@ -701,11 +707,12 @@ ExplainExecuteQuery(ExecuteStmt *execstmt, ExplainStmt *stmt,
 				pstmt->intoClause = execstmt->into;
 			}
 
-			ExplainOnePlan(pstmt, paramLI, stmt, tstate);
+			ExplainOnePlan(pstmt, stmt, query_string,
+						   paramLI, tstate);
 		}
 		else
 		{
-			ExplainOneUtility((Node *) pstmt, stmt, queryString,
+			ExplainOneUtility((Node *) pstmt, stmt, query_string,
 							  params, tstate);
 		}
 

src/backend/executor/functions.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/functions.c,v 1.131 2009/01/01 17:23:41 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/functions.c,v 1.132 2009/01/02 20:42:00 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -411,11 +411,13 @@ postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
 
 	if (IsA(es->stmt, PlannedStmt))
 		es->qd = CreateQueryDesc((PlannedStmt *) es->stmt,
+								 fcache->src,
 								 snapshot, InvalidSnapshot,
 								 dest,
 								 fcache->paramLI, false);
 	else
 		es->qd = CreateUtilityQueryDesc(es->stmt,
+										fcache->src,
 										snapshot,
 										dest,
 										fcache->paramLI);

src/backend/executor/spi.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/spi.c,v 1.203 2009/01/01 17:23:42 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/spi.c,v 1.204 2009/01/02 20:42:00 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1791,6 +1791,7 @@ _SPI_execute_plan(SPIPlanPtr plan, ParamListInfo paramLI,
 					snap = InvalidSnapshot;
 
 				qdesc = CreateQueryDesc((PlannedStmt *) stmt,
+										plansource->query_string,
 										snap, crosscheck_snapshot,
 										dest,
 										paramLI, false);

src/backend/tcop/pquery.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.128 2009/01/01 17:23:48 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.129 2009/01/02 20:42:00 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -36,6 +36,7 @@ Portal		ActivePortal = NULL;
 
 
 static void ProcessQuery(PlannedStmt *plan,
+			 const char *sourceText,
 			 ParamListInfo params,
 			 DestReceiver *dest,
 			 char *completionTag);
@@ -61,6 +62,7 @@ static void DoPortalRewind(Portal portal);
  */
 QueryDesc *
 CreateQueryDesc(PlannedStmt *plannedstmt,
+				const char *sourceText,
 				Snapshot snapshot,
 				Snapshot crosscheck_snapshot,
 				DestReceiver *dest,
@@ -72,6 +74,7 @@ CreateQueryDesc(PlannedStmt *plannedstmt,
 	qd->operation = plannedstmt->commandType;	/* operation */
 	qd->plannedstmt = plannedstmt;		/* plan */
 	qd->utilitystmt = plannedstmt->utilityStmt; /* in case DECLARE CURSOR */
+	qd->sourceText = sourceText;		/* query text */
 	qd->snapshot = RegisterSnapshot(snapshot);	/* snapshot */
 	/* RI check snapshot */
 	qd->crosscheck_snapshot = RegisterSnapshot(crosscheck_snapshot);
@@ -93,6 +96,7 @@ CreateQueryDesc(PlannedStmt *plannedstmt,
  */
 QueryDesc *
 CreateUtilityQueryDesc(Node *utilitystmt,
+					   const char *sourceText,
 					   Snapshot snapshot,
 					   DestReceiver *dest,
 					   ParamListInfo params)
@@ -102,6 +106,7 @@ CreateUtilityQueryDesc(Node *utilitystmt,
 	qd->operation = CMD_UTILITY;	/* operation */
 	qd->plannedstmt = NULL;
 	qd->utilitystmt = utilitystmt;		/* utility command */
+	qd->sourceText = sourceText;		/* query text */
 	qd->snapshot = RegisterSnapshot(snapshot);	/* snapshot */
 	qd->crosscheck_snapshot = InvalidSnapshot;	/* RI check snapshot */
 	qd->dest = dest;			/* output dest */
@@ -141,6 +146,7 @@ FreeQueryDesc(QueryDesc *qdesc)
  *		or PORTAL_ONE_RETURNING portal
  *
  *	plan: the plan tree for the query
+ *	sourceText: the source text of the query
  *	params: any parameters needed
  *	dest: where to send results
  *	completionTag: points to a buffer of size COMPLETION_TAG_BUFSIZE
@@ -153,6 +159,7 @@ FreeQueryDesc(QueryDesc *qdesc)
  */
 static void
 ProcessQuery(PlannedStmt *plan,
+			 const char *sourceText,
 			 ParamListInfo params,
 			 DestReceiver *dest,
 			 char *completionTag)
@@ -169,7 +176,7 @@ ProcessQuery(PlannedStmt *plan,
 	/*
 	 * Create the QueryDesc object
 	 */
-	queryDesc = CreateQueryDesc(plan,
+	queryDesc = CreateQueryDesc(plan, sourceText,
 								GetActiveSnapshot(), InvalidSnapshot,
 								dest, params, false);
 
@@ -503,6 +510,7 @@ PortalStart(Portal portal, ParamListInfo params, Snapshot snapshot)
 				 * the destination to DestNone.
 				 */
 				queryDesc = CreateQueryDesc((PlannedStmt *) linitial(portal->stmts),
+											portal->sourceText,
 											GetActiveSnapshot(),
 											InvalidSnapshot,
 											None_Receiver,
@@ -1258,6 +1266,7 @@ PortalRunMulti(Portal portal, bool isTopLevel,
 			{
 				/* statement can set tag string */
 				ProcessQuery(pstmt,
+							 portal->sourceText,
 							 portal->portalParams,
 							 dest, completionTag);
 			}
@@ -1265,6 +1274,7 @@ PortalRunMulti(Portal portal, bool isTopLevel,
 			{
 				/* stmt added by rewrite cannot set tag */
 				ProcessQuery(pstmt,
+							 portal->sourceText,
 							 portal->portalParams,
 							 altdest, NULL);
 			}

src/include/commands/explain.h

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994-5, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/commands/explain.h,v 1.37 2009/01/01 17:23:58 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/commands/explain.h,v 1.38 2009/01/02 20:42:00 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -38,8 +38,10 @@ extern void ExplainOneUtility(Node *utilityStmt, ExplainStmt *stmt,
 				  ParamListInfo params,
 				  TupOutputState *tstate);
 
-extern void ExplainOnePlan(PlannedStmt *plannedstmt, ParamListInfo params,
-			   ExplainStmt *stmt, TupOutputState *tstate);
+extern void ExplainOnePlan(PlannedStmt *plannedstmt, ExplainStmt *stmt,
+						   const char *queryString,
+						   ParamListInfo params,
+						   TupOutputState *tstate);
 
 extern void ExplainPrintPlan(StringInfo str, QueryDesc *queryDesc,
 							 bool analyze, bool verbose);

src/include/executor/execdesc.h

@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/executor/execdesc.h,v 1.39 2009/01/01 17:23:59 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/executor/execdesc.h,v 1.40 2009/01/02 20:42:00 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -37,6 +37,7 @@ typedef struct QueryDesc
 	CmdType		operation;		/* CMD_SELECT, CMD_UPDATE, etc. */
 	PlannedStmt *plannedstmt;	/* planner's output, or null if utility */
 	Node	   *utilitystmt;	/* utility statement, or null */
+	const char *sourceText;		/* source text of the query */
 	Snapshot	snapshot;		/* snapshot to use for query */
 	Snapshot	crosscheck_snapshot;	/* crosscheck for RI update/delete */
 	DestReceiver *dest;			/* the destination for tuple output */
@@ -54,6 +55,7 @@ typedef struct QueryDesc
 
 /* in pquery.c */
 extern QueryDesc *CreateQueryDesc(PlannedStmt *plannedstmt,
+				const char *sourceText,
 				Snapshot snapshot,
 				Snapshot crosscheck_snapshot,
 				DestReceiver *dest,
@@ -61,6 +63,7 @@ extern QueryDesc *CreateQueryDesc(PlannedStmt *plannedstmt,
 				bool doInstrument);
 
 extern QueryDesc *CreateUtilityQueryDesc(Node *utilitystmt,
+					   const char *sourceText,
 					   Snapshot snapshot,
 					   DestReceiver *dest,
 					   ParamListInfo params);