AUTOCOMMIT mode is now an available backend GUC variable; setting it

to false provides more SQL-spec-compliant behavior than we had before.
I am not sure that setting it false is actually a good idea yet; there
is a lot of client-side code that will probably be broken by turning
autocommit off.  But it's a start.

Loosely based on a patch by David Van Wie.

doc/src/sgml/release.sgml

 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/release.sgml,v 1.155 2002/08/30 00:28:40 tgl Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/release.sgml,v 1.156 2002/08/30 22:18:05 tgl Exp $
 -->
 
 <appendix id="release">
@@ -24,6 +24,7 @@ CDATA means the content is "SGML-free", so you can write without
 worries about funny characters.
 -->
 <literallayout><![CDATA[
+No-autocommit mode is available (set autocommit to off)
 Substantial improvements in functionality for functions returning sets
 Client libraries older than 6.3 no longer supported (version 0 protocol removed)
 PREPARE statement allows caching query plans for interactive statements

doc/src/sgml/runtime.sgml

 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.130 2002/08/30 16:50:49 momjian Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.131 2002/08/30 22:18:05 tgl Exp $
 -->
 
 <Chapter Id="runtime">
@@ -1135,6 +1135,29 @@ env PGOPTIONS='-c geqo=off' psql
 
    <para>
     <variablelist>
+     <varlistentry>
+      <term><varname>AUTOCOMMIT</varname> (<type>bool</type>)</term>
+      <indexterm><primary>autocommit</></>
+      <listitem>
+       <para>
+        If set to true, <productname>PostgreSQL</productname> will
+	automatically do a <command>COMMIT</> after each successful command
+	that is not inside an explicit transaction block (that is, unless a
+	<command>BEGIN</> with no matching <command>COMMIT</> has been
+	given).
+	If set to false, <productname>PostgreSQL</productname> will commit
+	the effects of commands only on receiving an explicit
+	<command>COMMIT</> command.  This mode can also be thought of as
+	implicitly issuing <command>BEGIN</> whenever a command is received
+	and <productname>PostgreSQL</productname> is not already inside
+	a transaction block.
+	The default is true, for compatibility with historical
+	<productname>PostgreSQL</productname> behavior.  But for maximum
+	compatibility with the SQL specification, set it to false.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><varname>AUSTRALIAN_TIMEZONES</varname> (<type>bool</type>)</term>
       <indexterm><primary>Australian time zones</></>

src/backend/access/transam/xact.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.130 2002/08/06 02:36:33 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.131 2002/08/30 22:18:05 tgl Exp $
  *
  * NOTES
  *		Transaction aborts can now occur two ways:
@@ -220,10 +220,15 @@ TransactionState CurrentTransactionState = &CurrentTransactionStateData;
 int			DefaultXactIsoLevel = XACT_READ_COMMITTED;
 int			XactIsoLevel;
 
+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;
 
@@ -1149,13 +1154,24 @@ CleanupTransaction(void)
 
 /* --------------------------------
  *		StartTransactionCommand
+ *
+ * preventChain, if true, forces autocommit behavior at the next
+ * CommitTransactionCommand call.
  * --------------------------------
  */
 void
-StartTransactionCommand(void)
+StartTransactionCommand(bool preventChain)
 {
 	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)
 	{
 			/*
@@ -1231,21 +1247,41 @@ StartTransactionCommand(void)
 
 /* --------------------------------
  *		CommitTransactionCommand
+ *
+ * forceCommit = true forces autocommit behavior even when autocommit is off.
  * --------------------------------
  */
 void
-CommitTransactionCommand(void)
+CommitTransactionCommand(bool forceCommit)
 {
 	TransactionState s = CurrentTransactionState;
 
 	switch (s->blockState)
 	{
 			/*
-			 * if we aren't in a transaction block, we just do our usual
-			 * transaction commit
+			 * 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.  This is needed so that commands
+			 * like VACUUM can ensure that the right things happen.
 			 */
 		case TBLOCK_DEFAULT:
-			CommitTransaction();
+			if (autocommit || forceCommit || suppressChain)
+				CommitTransaction();
+			else
+			{
+				BeginTransactionBlock();
+				Assert(s->blockState == TBLOCK_INPROGRESS);
+				/* This code must match the TBLOCK_INPROGRESS case below: */
+				CommandCounterIncrement();
+				MemoryContextResetAndDeleteChildren(TransactionCommandContext);
+			}
 			break;
 
 			/*
@@ -1406,7 +1442,10 @@ BeginTransactionBlock(void)
 	s->blockState = TBLOCK_BEGIN;
 
 	/*
-	 * do begin processing
+	 * 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.
 	 */
 
 	/*

src/backend/bootstrap/bootparse.y

@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/bootstrap/bootparse.y,v 1.50 2002/07/20 05:16:56 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/bootstrap/bootparse.y,v 1.51 2002/08/30 22:18:05 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -55,7 +55,7 @@
 static void
 do_start()
 {
-	StartTransactionCommand();
+	StartTransactionCommand(true);
 	elog(DEBUG3, "start transaction");
 }
 
@@ -63,7 +63,7 @@ do_start()
 static void
 do_end()
 {
-	CommitTransactionCommand();
+	CommitTransactionCommand(true);
 	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 1.138 2002/08/17 15:12:06 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/bootstrap/bootstrap.c,v 1.139 2002/08/30 22:18:05 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -448,7 +448,7 @@ BootstrapMain(int argc, char *argv[])
 	SetProcessingMode(BootstrapProcessing);
 
 	/* clean up processing */
-	StartTransactionCommand();
+	StartTransactionCommand(true);
 	cleanup();
 
 	/* not reached, here to make compiler happy */
@@ -821,7 +821,7 @@ cleanup()
 	}
 	if (boot_reldesc != NULL)
 		closerel(NULL);
-	CommitTransactionCommand();
+	CommitTransactionCommand(true);
 	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 1.32 2002/08/29 00:17:02 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/catalog/namespace.c,v 1.33 2002/08/30 22:18:05 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1610,11 +1610,11 @@ RemoveTempRelationsCallback(void)
 	{
 		/* Need to ensure we have a usable transaction. */
 		AbortOutOfAnyTransaction();
-		StartTransactionCommand();
+		StartTransactionCommand(true);
 
 		RemoveTempRelations(myTempNamespace);
 
-		CommitTransactionCommand();
+		CommitTransactionCommand(true);
 	}
 }
 

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 1.88 2002/08/05 03:29:16 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/async.c,v 1.89 2002/08/30 22:18:05 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -400,9 +400,9 @@ Async_UnlistenOnExit(void)
 	 */
 	AbortOutOfAnyTransaction();
 	/* Now we can do the unlisten */
-	StartTransactionCommand();
+	StartTransactionCommand(true);
 	Async_UnlistenAll();
-	CommitTransactionCommand();
+	CommitTransactionCommand(true);
 }
 
 /*
@@ -749,7 +749,7 @@ ProcessIncomingNotify(void)
 
 	notifyInterruptOccurred = 0;
 
-	StartTransactionCommand();
+	StartTransactionCommand(true);
 
 	lRel = heap_openr(ListenerRelationName, AccessExclusiveLock);
 	tdesc = RelationGetDescr(lRel);
@@ -803,7 +803,7 @@ ProcessIncomingNotify(void)
 	 */
 	heap_close(lRel, NoLock);
 
-	CommitTransactionCommand();
+	CommitTransactionCommand(true);
 
 	/*
 	 * Must flush the notify messages to ensure frontend gets them

src/backend/commands/indexcmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/indexcmds.c,v 1.85 2002/08/29 15:56:20 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/indexcmds.c,v 1.86 2002/08/30 22:18:05 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -735,15 +735,16 @@ ReindexDatabase(const char *dbname, bool force, bool all)
 	heap_close(relationRelation, AccessShareLock);
 
 	/* Now reindex each rel in a separate transaction */
-	CommitTransactionCommand();
+	CommitTransactionCommand(true);
 	for (i = 0; i < relcnt; i++)
 	{
-		StartTransactionCommand();
+		StartTransactionCommand(true);
 		if (reindex_relation(relids[i], force))
 			elog(NOTICE, "relation %u was reindexed", relids[i]);
-		CommitTransactionCommand();
+		CommitTransactionCommand(true);
 	}
-	StartTransactionCommand();
+	/* Tell xact.c not to chain the upcoming commit */
+	StartTransactionCommand(true);
 
 	MemoryContextDelete(private_context);
 }

src/backend/commands/vacuum.c

@@ -13,7 +13,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.234 2002/08/13 20:14:24 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.235 2002/08/30 22:18:05 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -273,7 +273,7 @@ vacuum(VacuumStmt *vacstmt)
 		}
 
 		/* matches the StartTransaction in PostgresMain() */
-		CommitTransactionCommand();
+		CommitTransactionCommand(true);
 	}
 
 	/*
@@ -296,14 +296,14 @@ vacuum(VacuumStmt *vacstmt)
 			 * return (else we leak memory while processing multiple tables).
 			 */
 			if (vacstmt->vacuum)
-				StartTransactionCommand();
+				StartTransactionCommand(true);
 			else
 				old_context = MemoryContextSwitchTo(anl_context);
 
 			analyze_rel(relid, vacstmt);
 
 			if (vacstmt->vacuum)
-				CommitTransactionCommand();
+				CommitTransactionCommand(true);
 			else
 			{
 				MemoryContextSwitchTo(old_context);
@@ -319,8 +319,12 @@ vacuum(VacuumStmt *vacstmt)
 	{
 		/* here, we are not in a transaction */
 
-		/* matches the CommitTransaction in PostgresMain() */
-		StartTransactionCommand();
+		/*
+		 * 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.
+		 */
+		StartTransactionCommand(true);
 
 		/*
 		 * If we did a database-wide VACUUM, update the database's pg_database
@@ -703,7 +707,7 @@ vacuum_rel(Oid relid, VacuumStmt *vacstmt, char expected_relkind)
 	Oid			toast_relid;
 
 	/* Begin a transaction for vacuuming this relation */
-	StartTransactionCommand();
+	StartTransactionCommand(true);
 
 	/*
 	 * Check for user-requested abort.	Note we want this to be inside a
@@ -719,7 +723,7 @@ vacuum_rel(Oid relid, VacuumStmt *vacstmt, char expected_relkind)
 							  ObjectIdGetDatum(relid),
 							  0, 0, 0))
 	{
-		CommitTransactionCommand();
+		CommitTransactionCommand(true);
 		return;
 	}
 
@@ -750,7 +754,7 @@ 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();
+		CommitTransactionCommand(true);
 		return;
 	}
 
@@ -763,7 +767,7 @@ 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();
+		CommitTransactionCommand(true);
 		return;
 	}
 
@@ -799,7 +803,7 @@ vacuum_rel(Oid relid, VacuumStmt *vacstmt, char expected_relkind)
 	/*
 	 * Complete the transaction and free all temporary memory used.
 	 */
-	CommitTransactionCommand();
+	CommitTransactionCommand(true);
 
 	/*
 	 * 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 1.286 2002/08/29 23:39:05 inoue Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.287 2002/08/30 22:18:06 tgl Exp $
  *
  * NOTES
  *	  this is the "main" module of the postgres backend and
@@ -860,7 +860,7 @@ static void
 start_xact_command(void)
 {
 	elog(DEBUG1, "StartTransactionCommand");
-	StartTransactionCommand();
+	StartTransactionCommand(false);
 }
 
 static void
@@ -872,7 +872,7 @@ finish_xact_command(void)
 	/* Now commit the command */
 	elog(DEBUG1, "CommitTransactionCommand");
 
-	CommitTransactionCommand();
+	CommitTransactionCommand(false);
 
 #ifdef SHOW_MEMORY_STATS
 	/* Print mem stats at each commit for leak tracking */
@@ -1664,7 +1664,7 @@ PostgresMain(int argc, char *argv[], const char *username)
 	if (!IsUnderPostmaster)
 	{
 		puts("\nPOSTGRES backend interactive interface ");
-		puts("$Revision: 1.286 $ $Date: 2002/08/29 23:39:05 $\n");
+		puts("$Revision: 1.287 $ $Date: 2002/08/30 22:18:06 $\n");
 	}
 
 	/*

src/backend/utils/init/postinit.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.111 2002/08/29 21:02:12 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.112 2002/08/30 22:18:06 tgl Exp $
  *
  *
  *-------------------------------------------------------------------------
@@ -330,7 +330,7 @@ InitPostgres(const char *dbname, const char *username)
 
 	/* start a new transaction here before access to db */
 	if (!bootstrap)
-		StartTransactionCommand();
+		StartTransactionCommand(true);
 
 	/*
 	 * It's now possible to do real access to the system catalogs.
@@ -394,7 +394,7 @@ InitPostgres(const char *dbname, const char *username)
 
 	/* close the transaction we started above */
 	if (!bootstrap)
-		CommitTransactionCommand();
+		CommitTransactionCommand(true);
 
 	/*
 	 * Check a normal user hasn't connected to a superuser reserved slot.

src/backend/utils/misc/guc.c

@@ -5,7 +5,7 @@
  * command, configuration file, and command line options.
  * See src/backend/utils/misc/README for more information.
  *
- * $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.88 2002/08/30 16:50:50 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.89 2002/08/30 22:18:07 tgl Exp $
  *
  * Copyright 2000 by PostgreSQL Global Development Group
  * Written by Peter Eisentraut <peter_e@gmx.net>.
@@ -58,6 +58,7 @@ extern int	PreAuthDelay;
 extern int	AuthenticationTimeout;
 extern int	StatementTimeout;
 extern int	CheckPointTimeout;
+extern bool autocommit;
 extern int	CommitDelay;
 extern int	CommitSiblings;
 extern bool FixBTree;
@@ -487,6 +488,10 @@ static struct config_bool
 		{ "db_user_namespace", PGC_SIGHUP }, &Db_user_namespace,
 		false, NULL, NULL
 	},
+	{
+		{ "autocommit", PGC_USERSET }, &autocommit, 
+		true, NULL, NULL
+	},
 
 	{
 		{ NULL, 0 }, NULL, false, NULL, NULL

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

@@ -68,8 +68,6 @@
 #checkpoint_segments = 3	# in logfile segments, min 1, 16MB each
 #checkpoint_timeout = 300	# range 30-3600, in seconds
 #
-#wal_files = 0	# range 0-64
-#
 #commit_delay = 0		# range 0-100000, in microseconds
 #commit_siblings = 5		# range 1-1000
 #
@@ -186,6 +184,7 @@
 #
 #	Misc
 #
+#autocommit = true
 #dynamic_library_path = '$libdir'
 #search_path = '$user,public'
 #datestyle = 'iso, us'

src/bin/psql/tab-complete.c

@@ -3,7 +3,7 @@
  *
  * Copyright 2000-2002 by PostgreSQL Global Development Group
  *
- * $Header: /cvsroot/pgsql/src/bin/psql/tab-complete.c,v 1.59 2002/08/30 18:15:23 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/bin/psql/tab-complete.c,v 1.60 2002/08/30 22:18:07 tgl Exp $
  */
 
 /*----------------------------------------------------------------------
@@ -246,6 +246,7 @@ psql_completion(char *text, int start, int end)
 		"australian_timezones",
 		"password_encryption",
 		"transform_null_equals",
+		"autocommit",
 
 		"default_statistics_target",
 		"geqo_threshold",

src/include/access/xact.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: xact.h,v 1.44 2002/06/20 20:29:43 momjian Exp $
+ * $Id: xact.h,v 1.45 2002/08/30 22:18:07 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -105,8 +105,8 @@ extern AbsoluteTime GetCurrentTransactionStartTimeUsec(int *usec);
 extern bool TransactionIdIsCurrentTransactionId(TransactionId xid);
 extern bool CommandIdIsCurrentCommandId(CommandId cid);
 extern void CommandCounterIncrement(void);
-extern void StartTransactionCommand(void);
-extern void CommitTransactionCommand(void);
+extern void StartTransactionCommand(bool preventChain);
+extern void CommitTransactionCommand(bool forceCommit);
 extern void AbortCurrentTransaction(void);
 extern void BeginTransactionBlock(void);
 extern void EndTransactionBlock(void);