Backend support for autocommit removed, per recent discussions. The

only remnant of this failed experiment is that the server will take
SET AUTOCOMMIT TO ON.  Still TODO: provide some client-side autocommit
logic in libpq.

src/backend/access/transam/xact.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.147 2003/05/02 20:54:33 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.148 2003/05/14 03:26:00 tgl Exp $
  *
  * NOTES
  *		Transaction aborts can now occur two ways:
@@ -212,15 +212,11 @@ int			XactIsoLevel;
 bool		DefaultXactReadOnly = false;
 bool		XactReadOnly;
 
-bool		autocommit = true;
-
 int			CommitDelay = 0;	/* precommit delay in microseconds */
 int			CommitSiblings = 5; /* number of concurrent xacts needed to
 								 * sleep */
 
 
-static bool suppressChain = false;
-
 static void (*_RollbackFunc) (void *) = NULL;
 static void *_RollbackData = NULL;
 
@@ -1125,23 +1121,12 @@ CleanupTransaction(void)
 
 /*
  *	StartTransactionCommand
- *
- *	preventChain, if true, forces autocommit behavior at the next
- *	CommitTransactionCommand call.
  */
 void
-StartTransactionCommand(bool preventChain)
+StartTransactionCommand(void)
 {
 	TransactionState s = CurrentTransactionState;
 
-	/*
-	 * Remember if caller wants to prevent autocommit-off chaining. This
-	 * is only allowed if not already in a transaction block.
-	 */
-	suppressChain = preventChain;
-	if (preventChain && s->blockState != TBLOCK_DEFAULT)
-		elog(ERROR, "StartTransactionCommand: can't prevent chain");
-
 	switch (s->blockState)
 	{
 			/*
@@ -1217,44 +1202,20 @@ StartTransactionCommand(bool preventChain)
 
 /*
  *	CommitTransactionCommand
- *
- *	forceCommit = true forces autocommit behavior even when autocommit is off.
  */
 void
-CommitTransactionCommand(bool forceCommit)
+CommitTransactionCommand(void)
 {
 	TransactionState s = CurrentTransactionState;
 
 	switch (s->blockState)
 	{
 			/*
-			 * If we aren't in a transaction block, and we are doing
-			 * autocommit, just do our usual transaction commit.  But if
-			 * we aren't doing autocommit, start a transaction block
-			 * automatically by switching to INPROGRESS state.	(We handle
-			 * this choice here, and not earlier, so that an explicit
-			 * BEGIN issued in autocommit-off mode won't issue strange
-			 * warnings.)
-			 *
-			 * Autocommit mode is forced by either a true forceCommit
-			 * parameter to me, or a true preventChain parameter to the
-			 * preceding StartTransactionCommand call, or a
-			 * PreventTransactionChain call during the transaction.
-			 * (The parameters could be omitted, but it turns out most
-			 * callers of StartTransactionCommand/CommitTransactionCommand
-			 * want to force autocommit, so making them all call
-			 * PreventTransactionChain would just be extra notation.)
+			 * If we aren't in a transaction block, just do our usual
+			 * transaction commit.
 			 */
 		case TBLOCK_DEFAULT:
-			if (autocommit || forceCommit || suppressChain)
-				CommitTransaction();
-			else
-			{
-				BeginTransactionBlock();
-				Assert(s->blockState == TBLOCK_INPROGRESS);
-				/* This code must match the TBLOCK_INPROGRESS case below: */
-				CommandCounterIncrement();
-			}
+			CommitTransaction();
 			break;
 
 			/*
@@ -1323,10 +1284,7 @@ AbortCurrentTransaction(void)
 			 */
 		case TBLOCK_DEFAULT:
 			AbortTransaction();
-			if (autocommit || suppressChain)
-				CleanupTransaction();
-			else
-				s->blockState = TBLOCK_ABORT;
+			CleanupTransaction();
 			break;
 
 			/*
@@ -1396,9 +1354,7 @@ AbortCurrentTransaction(void)
  *	If we have already started a transaction block, issue an error; also issue
  *	an error if we appear to be running inside a user-defined function (which
  *	could issue more commands and possibly cause a failure after the statement
- *	completes).  In autocommit-off mode, we allow the statement if a block is
- *	not already started, and force the statement to be autocommitted despite
- *	the mode.
+ *	completes).
  *
  *	stmtNode: pointer to parameter block for statement; this is used in
  *	a very klugy way to determine whether we are inside a function.
@@ -1428,14 +1384,7 @@ PreventTransactionChain(void *stmtNode, const char *stmtType)
 	/* If we got past IsTransactionBlock test, should be in default state */
 	if (CurrentTransactionState->blockState != TBLOCK_DEFAULT)
 		elog(ERROR, "PreventTransactionChain: can't prevent chain");
-	/* okay to set the flag */
-	suppressChain = true;
-	/* If we're in autocommit-off node, generate a notice */
-	if (!autocommit)
-	{
-		/* translator: %s represents an SQL statement name */
-		elog(NOTICE, "%s will be committed automatically", stmtType);
-	}
+	/* all okay */
 }
 
 /*
@@ -1470,12 +1419,6 @@ RequireTransactionChain(void *stmtNode, const char *stmtType)
 	 */
 	if (!MemoryContextContains(QueryContext, stmtNode))
 		return;
-	/*
-	 * If we are in autocommit-off mode then it's okay, because this
-	 * statement will itself start a transaction block.
-	 */
-	if (!autocommit && !suppressChain)
-		return;
 	/* translator: %s represents an SQL statement name */
 	elog(ERROR, "%s may only be used in begin/end transaction blocks",
 		 stmtType);
@@ -1507,10 +1450,7 @@ BeginTransactionBlock(void)
 	s->blockState = TBLOCK_BEGIN;
 
 	/*
-	 * do begin processing.  NOTE: if you put anything here, check that it
-	 * behaves properly in both autocommit-on and autocommit-off modes. In
-	 * the latter case we will already have done some work in the new
-	 * transaction.
+	 * do begin processing here.  Nothing to do at present.
 	 */
 
 	/*

src/backend/bootstrap/bootparse.y

@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/bootstrap/bootparse.y,v 1.55 2002/11/11 22:19:21 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/bootstrap/bootparse.y,v 1.56 2003/05/14 03:26:00 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -55,7 +55,7 @@
 static void
 do_start()
 {
-	StartTransactionCommand(true);
+	StartTransactionCommand();
 	elog(DEBUG3, "start transaction");
 }
 
@@ -63,7 +63,7 @@ do_start()
 static void
 do_end()
 {
-	CommitTransactionCommand(true);
+	CommitTransactionCommand();
 	elog(DEBUG3, "commit transaction");
 	if (isatty(0))
 	{

src/backend/bootstrap/bootstrap.c

@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/bootstrap/bootstrap.c,v 1.156 2003/05/08 14:49:03 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/bootstrap/bootstrap.c,v 1.157 2003/05/14 03:26:00 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -479,7 +479,7 @@ BootstrapMain(int argc, char *argv[])
 	SetProcessingMode(BootstrapProcessing);
 
 	/* clean up processing */
-	StartTransactionCommand(true);
+	StartTransactionCommand();
 	cleanup();
 
 	/* not reached, here to make compiler happy */
@@ -851,7 +851,7 @@ cleanup()
 	}
 	if (boot_reldesc != NULL)
 		closerel(NULL);
-	CommitTransactionCommand(true);
+	CommitTransactionCommand();
 	proc_exit(Warnings);
 }
 

src/backend/catalog/namespace.c

@@ -13,7 +13,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/catalog/namespace.c,v 1.50 2003/04/24 21:16:42 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/catalog/namespace.c,v 1.51 2003/05/14 03:26:01 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1711,11 +1711,11 @@ RemoveTempRelationsCallback(void)
 	{
 		/* Need to ensure we have a usable transaction. */
 		AbortOutOfAnyTransaction();
-		StartTransactionCommand(true);
+		StartTransactionCommand();
 
 		RemoveTempRelations(myTempNamespace);
 
-		CommitTransactionCommand(true);
+		CommitTransactionCommand();
 	}
 }
 

src/backend/commands/async.c

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/async.c,v 1.93 2003/04/22 00:08:06 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/async.c,v 1.94 2003/05/14 03:26:01 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -399,9 +399,9 @@ Async_UnlistenOnExit(void)
 	 */
 	AbortOutOfAnyTransaction();
 	/* Now we can do the unlisten */
-	StartTransactionCommand(true);
+	StartTransactionCommand();
 	Async_UnlistenAll();
-	CommitTransactionCommand(true);
+	CommitTransactionCommand();
 }
 
 /*
@@ -769,7 +769,7 @@ ProcessIncomingNotify(void)
 
 	notifyInterruptOccurred = 0;
 
-	StartTransactionCommand(true);
+	StartTransactionCommand();
 
 	lRel = heap_openr(ListenerRelationName, AccessExclusiveLock);
 	tdesc = RelationGetDescr(lRel);
@@ -823,7 +823,7 @@ ProcessIncomingNotify(void)
 	 */
 	heap_close(lRel, NoLock);
 
-	CommitTransactionCommand(true);
+	CommitTransactionCommand();
 
 	/*
 	 * Must flush the notify messages to ensure frontend gets them

src/backend/commands/cluster.c

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/cluster.c,v 1.108 2003/05/02 20:54:33 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/cluster.c,v 1.109 2003/05/14 03:26:01 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -205,7 +205,7 @@ cluster(ClusterStmt *stmt)
 		rvs = get_tables_to_cluster(cluster_context);
 
 		/* Commit to get out of starting transaction */
-		CommitTransactionCommand(true);
+		CommitTransactionCommand();
 
 		/* Ok, now that we've got them all, cluster them one by one */
 		foreach (rv, rvs)
@@ -213,14 +213,14 @@ cluster(ClusterStmt *stmt)
 			RelToCluster	*rvtc = (RelToCluster *) lfirst(rv);
 
 			/* Start a new transaction for each relation. */
-			StartTransactionCommand(true);
+			StartTransactionCommand();
 			SetQuerySnapshot();	/* might be needed for functional index */
 			cluster_rel(rvtc, true);
-			CommitTransactionCommand(true);
+			CommitTransactionCommand();
 		}
 
 		/* Start a new transaction for the cleanup work. */
-		StartTransactionCommand(true);
+		StartTransactionCommand();
 
 		/* Clean up working storage */
 		MemoryContextDelete(cluster_context);

src/backend/commands/indexcmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/indexcmds.c,v 1.98 2003/05/02 20:54:33 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/indexcmds.c,v 1.99 2003/05/14 03:26:01 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -769,17 +769,16 @@ ReindexDatabase(const char *dbname, bool force, bool all)
 	heap_close(relationRelation, AccessShareLock);
 
 	/* Now reindex each rel in a separate transaction */
-	CommitTransactionCommand(true);
+	CommitTransactionCommand();
 	for (i = 0; i < relcnt; i++)
 	{
-		StartTransactionCommand(true);
+		StartTransactionCommand();
 		SetQuerySnapshot();		/* might be needed for functional index */
 		if (reindex_relation(relids[i], force))
 			elog(NOTICE, "relation %u was reindexed", relids[i]);
-		CommitTransactionCommand(true);
+		CommitTransactionCommand();
 	}
-	/* Tell xact.c not to chain the upcoming commit */
-	StartTransactionCommand(true);
+	StartTransactionCommand();
 
 	MemoryContextDelete(private_context);
 }

src/backend/commands/vacuum.c

@@ -13,7 +13,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.252 2003/05/02 20:54:33 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.253 2003/05/14 03:26:01 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -275,7 +275,7 @@ vacuum(VacuumStmt *vacstmt)
 		}
 
 		/* matches the StartTransaction in PostgresMain() */
-		CommitTransactionCommand(true);
+		CommitTransactionCommand();
 	}
 
 	/*
@@ -303,7 +303,7 @@ vacuum(VacuumStmt *vacstmt)
 			 */
 			if (vacstmt->vacuum)
 			{
-				StartTransactionCommand(true);
+				StartTransactionCommand();
 				SetQuerySnapshot();	/* might be needed for functional index */
 			}
 			else
@@ -312,7 +312,7 @@ vacuum(VacuumStmt *vacstmt)
 			analyze_rel(relid, vacstmt);
 
 			if (vacstmt->vacuum)
-				CommitTransactionCommand(true);
+				CommitTransactionCommand();
 			else
 			{
 				MemoryContextSwitchTo(old_context);
@@ -330,11 +330,9 @@ vacuum(VacuumStmt *vacstmt)
 
 		/*
 		 * This matches the CommitTransaction waiting for us in
-		 * PostgresMain(). We tell xact.c not to chain the upcoming
-		 * commit, so that a VACUUM doesn't start a transaction block,
-		 * even when autocommit is off.
+		 * PostgresMain().
 		 */
-		StartTransactionCommand(true);
+		StartTransactionCommand();
 
 		/*
 		 * If it was a database-wide VACUUM, print FSM usage statistics
@@ -729,7 +727,7 @@ vacuum_rel(Oid relid, VacuumStmt *vacstmt, char expected_relkind)
 	bool		result;
 
 	/* Begin a transaction for vacuuming this relation */
-	StartTransactionCommand(true);
+	StartTransactionCommand();
 	SetQuerySnapshot();			/* might be needed for functional index */
 
 	/*
@@ -746,7 +744,7 @@ vacuum_rel(Oid relid, VacuumStmt *vacstmt, char expected_relkind)
 							  ObjectIdGetDatum(relid),
 							  0, 0, 0))
 	{
-		CommitTransactionCommand(true);
+		CommitTransactionCommand();
 		return true;			/* okay 'cause no data there */
 	}
 
@@ -778,7 +776,7 @@ vacuum_rel(Oid relid, VacuumStmt *vacstmt, char expected_relkind)
 		elog(WARNING, "Skipping \"%s\" --- only table or database owner can VACUUM it",
 			 RelationGetRelationName(onerel));
 		relation_close(onerel, lmode);
-		CommitTransactionCommand(true);
+		CommitTransactionCommand();
 		return false;
 	}
 
@@ -791,7 +789,7 @@ vacuum_rel(Oid relid, VacuumStmt *vacstmt, char expected_relkind)
 		elog(WARNING, "Skipping \"%s\" --- can not process indexes, views or special system tables",
 			 RelationGetRelationName(onerel));
 		relation_close(onerel, lmode);
-		CommitTransactionCommand(true);
+		CommitTransactionCommand();
 		return false;
 	}
 
@@ -805,7 +803,7 @@ vacuum_rel(Oid relid, VacuumStmt *vacstmt, char expected_relkind)
 	if (isOtherTempNamespace(RelationGetNamespace(onerel)))
 	{
 		relation_close(onerel, lmode);
-		CommitTransactionCommand(true);
+		CommitTransactionCommand();
 		return true;			/* assume no long-lived data in temp tables */
 	}
 
@@ -843,7 +841,7 @@ vacuum_rel(Oid relid, VacuumStmt *vacstmt, char expected_relkind)
 	/*
 	 * Complete the transaction and free all temporary memory used.
 	 */
-	CommitTransactionCommand(true);
+	CommitTransactionCommand();
 
 	/*
 	 * If the relation has a secondary toast rel, vacuum that too while we

src/backend/tcop/postgres.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.343 2003/05/12 16:48:17 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.344 2003/05/14 03:26:01 tgl Exp $
  *
  * NOTES
  *	  this is the "main" module of the postgres backend and
@@ -85,8 +85,6 @@ sigjmp_buf	Warn_restart;
 bool		Warn_restart_ready = false;
 bool		InError = false;
 
-extern bool	autocommit;
-
 /*
  * Flags for expensive function optimization -- JMH 3/9/92
  */
@@ -148,7 +146,7 @@ static int	InteractiveBackend(StringInfo inBuf);
 static int	SocketBackend(StringInfo inBuf);
 static int	ReadCommand(StringInfo inBuf);
 static void start_xact_command(void);
-static void finish_xact_command(bool forceCommit);
+static void finish_xact_command(void);
 static void SigHupHandler(SIGNAL_ARGS);
 static void FloatExceptionHandler(SIGNAL_ARGS);
 
@@ -861,20 +859,15 @@ exec_simple_query(const char *query_string)
 
 		PortalDrop(portal, false);
 
-
-		if (IsA(parsetree, TransactionStmt) ||
-			IsA(parsetree, VariableSetStmt) ||
-			IsA(parsetree, VariableShowStmt) ||
-			IsA(parsetree, VariableResetStmt))
+		if (IsA(parsetree, TransactionStmt))
 		{
 			/*
-			 * If this was a transaction control statement or a variable
-			 * set/show/reset statement, commit it.  We will start a
-			 * new xact command for the next command (if any).
+			 * If this was a transaction control statement, commit it.
+			 * We will start a new xact command for the next command (if any).
 			 */
-			finish_xact_command(true);
+			finish_xact_command();
 		}
-		else if (lnext(parsetree_item) == NIL || !autocommit)
+		else if (lnext(parsetree_item) == NIL)
 		{
 			/*
 			 * If this is the last parsetree of the query string, close down
@@ -886,7 +879,7 @@ exec_simple_query(const char *query_string)
 			 * historical Postgres behavior, we do not force a transaction
 			 * boundary between queries appearing in a single query string.
 			 */
-			finish_xact_command(false);
+			finish_xact_command();
 		}
 		else
 		{
@@ -907,6 +900,11 @@ exec_simple_query(const char *query_string)
 		EndCommand(completionTag, dest);
 	}							/* end loop over parsetrees */
 
+	/*
+	 * Close down transaction statement, if one is open.
+	 */
+	finish_xact_command();
+
 	/*
 	 * If there were no parsetrees, return EmptyQueryResponse message.
 	 */
@@ -915,11 +913,6 @@ exec_simple_query(const char *query_string)
 
 	QueryContext = NULL;
 
-	/*
-	 * Close down transaction statement, if one is open.
-	 */
-	finish_xact_command(false);
-
 	/*
 	 * Finish up monitoring.
 	 */
@@ -1531,7 +1524,7 @@ exec_execute_message(const char *portal_name, long max_rows)
 			 * If this was a transaction control statement, commit it.  We will
 			 * start a new xact command for the next command (if any).
 			 */
-			finish_xact_command(true);
+			finish_xact_command();
 		}
 		else
 		{
@@ -1657,7 +1650,7 @@ start_xact_command(void)
 	if (!xact_started)
 	{
 		elog(DEBUG2, "StartTransactionCommand");
-		StartTransactionCommand(false);
+		StartTransactionCommand();
 
 		/* Set statement timeout running, if any */
 		if (StatementTimeout > 0)
@@ -1668,7 +1661,7 @@ start_xact_command(void)
 }
 
 static void
-finish_xact_command(bool forceCommit)
+finish_xact_command(void)
 {
 	if (xact_started)
 	{
@@ -1681,7 +1674,7 @@ finish_xact_command(bool forceCommit)
 		/* Now commit the command */
 		elog(DEBUG2, "CommitTransactionCommand");
 
-		CommitTransactionCommand(forceCommit);
+		CommitTransactionCommand();
 
 #ifdef SHOW_MEMORY_STATS
 		/* Print mem stats at each commit for leak tracking */
@@ -2532,7 +2525,7 @@ PostgresMain(int argc, char *argv[], const char *username)
 	if (!IsUnderPostmaster)
 	{
 		puts("\nPOSTGRES backend interactive interface ");
-		puts("$Revision: 1.343 $ $Date: 2003/05/12 16:48:17 $\n");
+		puts("$Revision: 1.344 $ $Date: 2003/05/14 03:26:01 $\n");
 	}
 
 	/*
@@ -2810,7 +2803,7 @@ PostgresMain(int argc, char *argv[], const char *username)
 				}
 
 				/* commit the function-invocation transaction */
-				finish_xact_command(false);
+				finish_xact_command();
 
 				send_rfq = true;
 				break;
@@ -2894,7 +2887,7 @@ PostgresMain(int argc, char *argv[], const char *username)
 
 			case 'S':				/* sync */
 				pq_getmsgend(input_message);
-				finish_xact_command(false);
+				finish_xact_command();
 				send_rfq = true;
 				break;
 

src/backend/utils/init/postinit.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.120 2003/04/25 19:45:08 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.121 2003/05/14 03:26:02 tgl Exp $
  *
  *
  *-------------------------------------------------------------------------
@@ -334,7 +334,7 @@ InitPostgres(const char *dbname, const char *username)
 
 	/* start a new transaction here before access to db */
 	if (!bootstrap)
-		StartTransactionCommand(true);
+		StartTransactionCommand();
 
 	/*
 	 * It's now possible to do real access to the system catalogs.
@@ -420,7 +420,7 @@ InitPostgres(const char *dbname, const char *username)
 
 	/* close the transaction we started above */
 	if (!bootstrap)
-		CommitTransactionCommand(true);
+		CommitTransactionCommand();
 }
 
 /*

src/backend/utils/misc/guc.c

@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.123 2003/05/06 20:26:27 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.124 2003/05/14 03:26:02 tgl Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -69,7 +69,6 @@ extern bool Log_connections;
 extern int	PreAuthDelay;
 extern int	AuthenticationTimeout;
 extern int	CheckPointTimeout;
-extern bool autocommit;
 extern int	CommitDelay;
 extern int	CommitSiblings;
 extern char *preload_libraries_string;
@@ -92,6 +91,7 @@ static const char *assign_min_error_statement(const char *newval, bool doit,
 						   bool interactive);
 static const char *assign_msglvl(int *var, const char *newval,
 			  bool doit, bool interactive);
+static bool assign_phony_autocommit(bool newval, bool doit, bool interactive);
 
 
 /*
@@ -134,6 +134,7 @@ int			client_min_messages = NOTICE;
 static char *log_min_error_statement_str;
 static char *log_min_messages_str;
 static char *client_min_messages_str;
+static bool phony_autocommit;
 static double phony_random_seed;
 static char *client_encoding_string;
 static char *datestyle_string;
@@ -526,8 +527,12 @@ static struct config_bool
 		false, NULL, NULL
 	},
 	{
-		{"autocommit", PGC_USERSET}, &autocommit,
-		true, NULL, NULL
+		/*
+		 * This var doesn't do anything; it's just here so that we won't
+		 * choke on SET AUTOCOMMIT TO ON from 7.3-vintage clients.
+		 */
+		{"autocommit", PGC_USERSET, GUC_NO_SHOW_ALL}, &phony_autocommit,
+		true, assign_phony_autocommit, NULL
 	},
 	{
 		{"default_transaction_read_only", PGC_USERSET}, &DefaultXactReadOnly,
@@ -3429,6 +3434,18 @@ assign_msglvl(int *var, const char *newval, bool doit, bool interactive)
 	return newval;				/* OK */
 }
 
+static bool
+assign_phony_autocommit(bool newval, bool doit, bool interactive)
+{
+	if (!newval)
+	{
+		if (doit && interactive)
+			elog(ERROR, "SET AUTOCOMMIT TO OFF is no longer supported");
+		return false;
+	}
+	return true;
+}
+
 
 #include "guc-file.c"
 

src/backend/utils/misc/postgresql.conf.sample

@@ -198,7 +198,6 @@
 #
 #	Misc
 #
-#autocommit = true
 #dynamic_library_path = '$libdir'
 #search_path = '$user,public'	# schema names
 #datestyle = 'iso, us'