Index: doc/src/sgml/ref/psql-ref.sgml
===================================================================
RCS file: /projects/cvsroot/pgsql-server/doc/src/sgml/ref/psql-ref.sgml,v
retrieving revision 1.122
diff -u -r1.122 psql-ref.sgml
--- doc/src/sgml/ref/psql-ref.sgml	20 Sep 2004 18:51:17 -0000	1.122
+++ doc/src/sgml/ref/psql-ref.sgml	23 Sep 2004 19:51:36 -0000
@@ -2021,6 +2021,32 @@
       </varlistentry>
 
       <varlistentry>
+        <term><varname>IMPLICIT_SAVEPOINTS</varname></term>
+        <listitem>
+        <para>
+         When <literal>on</> (default is <literal>off</>) a savepoint is created
+         before each interactive SQL command executed in <application>psql</>. If
+         the command results in an error, <application>psql</> will rollback to
+         the created savepoint. It thereby protects the user from a rollback of
+         the whole transaction. This option has no effect on none-interactive
+         mode, i.e. when commands are read from a file from <acronym>stdin</> or
+         using <command>\i</>. A SQL script cannot react to an error and the
+         behaviour would have unexpected results.
+        </para>
+
+        <note>
+        <para>
+         Savepoints have a rather high cost in the current implementation of
+         <productname>PostgreSQL</> (shared memory). Also keep in mind that
+         locks are held in transactions until commit. For those two reasons
+         you should not make transactions longer then neccessary in
+         interactive mode.
+        </para>
+        </note>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
         <term><varname>LASTOID</varname></term>
         <listitem>
         <para>
Index: src/bin/psql/command.c
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/bin/psql/command.c,v
retrieving revision 1.125
diff -u -r1.125 command.c
--- src/bin/psql/command.c	29 Aug 2004 05:06:54 -0000	1.125
+++ src/bin/psql/command.c	23 Sep 2004 19:51:36 -0000
@@ -1261,6 +1261,7 @@
 	FILE	   *fd;
 	int			result;
 	char	   *oldfilename;
+	bool		impl_savepoints_state;
 
 	if (!filename)
 		return false;
@@ -1274,11 +1275,19 @@
 		return false;
 	}
 
+	/*
+	 * Disable implicit savepoints during processing commands from files.
+	 */
+	impl_savepoints_state = pset.impl_savepoints_disabled;
+	pset.impl_savepoints_disabled = true;
+
 	oldfilename = pset.inputfile;
 	pset.inputfile = filename;
 	result = MainLoop(fd);
 	fclose(fd);
 	pset.inputfile = oldfilename;
+
+	pset.impl_savepoints_disabled = impl_savepoints_state;
 	return result;
 }
 
Index: src/bin/psql/common.c
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/bin/psql/common.c,v
retrieving revision 1.91
diff -u -r1.91 common.c
--- src/bin/psql/common.c	20 Sep 2004 18:51:19 -0000	1.91
+++ src/bin/psql/common.c	23 Sep 2004 19:51:36 -0000
@@ -61,7 +61,6 @@
 
 extern bool prompt_state;
 
-
 static bool command_no_begin(const char *query);
 
 
@@ -865,6 +864,7 @@
 	TimevalStruct before,
 				after;
 	bool		OK;
+	bool		implicit_savepoint = false;
 
 	if (!pset.db)
 	{
@@ -908,6 +908,26 @@
 		PQclear(results);
 	}
 
+	/*
+	 * Implicit savepoints make it possible to only rollback the last statement
+	 * on errors (interactive mode only, backend version >= 8.0).
+	 * 
+	 * Note: We assume that the savepoint pg_internal_psql will not be used by a user.
+	 */
+	if (PQtransactionStatus(pset.db) == PQTRANS_INTRANS &&
+		PQserverVersion(pset.db) >= 80000 &&
+		GetVariableBool(pset.vars, "IMPLICIT_SAVEPOINTS") &&
+		!pset.impl_savepoints_disabled &&
+		!pset.notty)
+	{
+		/* use PSQLexec instead of PQexec here, so -E prints this query */
+		results = PSQLexec("SAVEPOINT pg_internal_psql", false);
+		if (!results)		
+			return false;
+		PQclear(results);
+		implicit_savepoint = true;
+	}
+
 	if (pset.timing)
 		GETTIMEOFDAY(&before);
 
@@ -943,6 +963,26 @@
 
 	PrintNotifications();
 
+	/*
+	 * If we have created an implicit savepoint, the query failed, and the
+	 * connection is in transaction aborted state, try to rollback to the
+	 * savepoint set before executing the user query.
+	 * 
+	 * Note: we must not release the savepoint if there is no error since that
+	 * would have the side effect of releasing any savepoint created by the user
+	 * in the executed query.
+	 * 
+	 * Should we send a message to the user here?
+	 */
+	if (!OK
+		&& implicit_savepoint
+		&& PQtransactionStatus(pset.db) == PQTRANS_INERROR)
+	{
+		results = PSQLexec("ROLLBACK TO pg_internal_psql", false);
+		if (results)
+			PQclear(results);
+	}
+
 	return OK;
 }
 
Index: src/bin/psql/startup.c
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/bin/psql/startup.c,v
retrieving revision 1.100
diff -u -r1.100 startup.c
--- src/bin/psql/startup.c	13 Sep 2004 23:07:12 -0000	1.100
+++ src/bin/psql/startup.c	23 Sep 2004 19:51:36 -0000
@@ -146,6 +146,10 @@
 	SetVariable(pset.vars, "VERBOSITY", "default");
 	pset.verbosity = PQERRORS_DEFAULT;
 
+	/* Default values for implicit savepoints */
+	SetVariable(pset.vars, "IMPLICIT_SAVEPOINTS", "off");
+	pset.impl_savepoints_disabled = false;
+
 	pset.notty = (!isatty(fileno(stdin)) || !isatty(fileno(stdout)));
 
 	/* This is obsolete and should be removed sometime. */