Make SET really not start a transaction.

doc/src/sgml/ref/reset.sgml

 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/ref/reset.sgml,v 1.16 2002/10/09 04:59:38 momjian Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/ref/reset.sgml,v 1.17 2002/10/13 16:55:05 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -68,7 +68,7 @@ SET <replaceable class="parameter">variable</replaceable> TO DEFAULT
   </para>
 
   <para>
-   See the <command>SHOW</> manual page for details on the transaction
+   See the <command>SET</> manual page for details on the transaction
    behavior of <command>RESET</>.
   </para>
 

doc/src/sgml/ref/set.sgml

 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/ref/set.sgml,v 1.67 2002/10/09 16:27:48 momjian Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/ref/set.sgml,v 1.68 2002/10/13 16:55:05 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -109,9 +109,10 @@ SET [ SESSION | LOCAL ] TIME ZONE { <replaceable class="PARAMETER">timezone</rep
   </para>
 
   <para>
-   With <literal>autocommit</> set to <literal>off</>, <command>SET</>
+   Even with <literal>autocommit</> set to <literal>off</>, <command>SET</>
    does not start a new transaction block. See the
-   <literal>autocommit</> section of the documentation for details.
+   <literal>autocommit</> section of the <citetitle>Administrator's
+   Guide</citetitle> for details.
   </para>
 
   <para>

doc/src/sgml/ref/show.sgml

 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/ref/show.sgml,v 1.21 2002/09/01 01:59:48 momjian Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/ref/show.sgml,v 1.22 2002/10/13 16:55:05 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -60,6 +60,13 @@ SHOW ALL
    command-line flag when starting the
    <application>postmaster</application>.
   </para>
+
+  <para>
+   Even with <literal>autocommit</> set to <literal>off</>, <command>SHOW</>
+   does not start a new transaction block. See the
+   <literal>autocommit</> section of the <citetitle>Administrator's
+   Guide</citetitle> for details.
+  </para>
  </refsect1>
 
  <refsect1>

doc/src/sgml/runtime.sgml

 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.144 2002/10/09 04:59:38 momjian Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.145 2002/10/13 16:55:05 tgl Exp $
 -->
 
 <Chapter Id="runtime">
@@ -1236,7 +1236,7 @@ env PGOPTIONS='-c geqo=off' psql
 	<command>BEGIN</> with no matching <command>COMMIT</> has been
 	given).
 	If set to false, <productname>PostgreSQL</productname> will
-	commit the commands only when receiving an explicit
+	commit only upon receiving an explicit
 	<command>COMMIT</> command. This mode can also be thought of as
 	implicitly issuing <command>BEGIN</> whenever a command is
 	received that is not already inside a transaction block. The
@@ -1247,16 +1247,16 @@ env PGOPTIONS='-c geqo=off' psql
        </para>
        <note>
         <para>
-	 With <varname>autocommit</> set to false, <command>SET</>,
+	 Even with <varname>autocommit</> set to false, <command>SET</>,
 	 <command>SHOW</>, and <command>RESET</> do not start new
 	 transaction blocks. They are run in their own transactions.
-	 Once another command is issued, multi-statement transaction
-	 behavior begins and any <command>SET</>, <command>SHOW</>, or
+	 Once another command is issued, a transaction block
+	 begins and any <command>SET</>, <command>SHOW</>, or
 	 <command>RESET</> commands are considered to be part of the
 	 transaction, i.e. they are committed or rolled back depending
-	 on the completion status of the transaction. To have
-	 <command>SET</>, <command>SHOW</>, and <command>RESET</>
-	 commands at the start of a transaction, use <command>BEGIN</>
+	 on the completion status of the transaction. To execute a
+	 <command>SET</>, <command>SHOW</>, or <command>RESET</>
+	 command at the start of a transaction block, use <command>BEGIN</>
 	 first.
         </para>
        </note>

src/backend/tcop/postgres.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.300 2002/10/09 04:59:38 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.301 2002/10/13 16:55:05 tgl Exp $
  *
  * NOTES
  *	  this is the "main" module of the postgres backend and
@@ -76,7 +76,6 @@ char	   *debug_query_string; /* for pgmonitor and
 CommandDest whereToSendOutput = Debug;
 
 extern int	StatementTimeout;
-extern bool autocommit;
 
 static bool dontExecute = false;
 
@@ -620,15 +619,11 @@ pg_exec_query_string(StringInfo query_string,	/* string to execute */
 	foreach(parsetree_item, parsetree_list)
 	{
 		Node	   *parsetree = (Node *) lfirst(parsetree_item);
-		bool		isTransactionStmt;
 		const char *commandTag;
 		char		completionTag[COMPLETION_TAG_BUFSIZE];
 		List	   *querytree_list,
 				   *querytree_item;
 
-		/* Transaction control statements need some special handling */
-		isTransactionStmt = IsA(parsetree, TransactionStmt);
-
 		/*
 		 * First we set the command-completion tag to the main query (as
 		 * opposed to each of the others that may be generated by analyze
@@ -653,7 +648,7 @@ pg_exec_query_string(StringInfo query_string,	/* string to execute */
 		{
 			bool		allowit = false;
 
-			if (isTransactionStmt)
+			if (IsA(parsetree, TransactionStmt))
 			{
 				TransactionStmt *stmt = (TransactionStmt *) parsetree;
 
@@ -698,6 +693,7 @@ pg_exec_query_string(StringInfo query_string,	/* string to execute */
 		foreach(querytree_item, querytree_list)
 		{
 			Query	   *querytree = (Query *) lfirst(querytree_item);
+			bool		endTransactionBlock = false;
 
 			/* Make sure we are in a transaction command */
 			if (!xact_started)
@@ -733,6 +729,13 @@ pg_exec_query_string(StringInfo query_string,	/* string to execute */
 					IsA(utilityStmt, ReindexStmt))
 					SetQuerySnapshot();
 
+				/* end transaction block if transaction or variable stmt */
+				if (IsA(utilityStmt, TransactionStmt) ||
+					IsA(utilityStmt, VariableSetStmt) ||
+					IsA(utilityStmt, VariableShowStmt) ||
+					IsA(utilityStmt, VariableResetStmt))
+					endTransactionBlock = true;
+
 				if (querytree->originalQuery)
 				{
 					/* utility statement can override default tag string */
@@ -805,7 +808,7 @@ pg_exec_query_string(StringInfo query_string,	/* string to execute */
 			 * visible to subsequent ones.	In particular we'd better do
 			 * so before checking constraints.
 			 */
-			if (!isTransactionStmt)
+			if (!endTransactionBlock)
 				CommandCounterIncrement();
 
 			/*
@@ -820,13 +823,13 @@ pg_exec_query_string(StringInfo query_string,	/* string to execute */
 			MemoryContextResetAndDeleteChildren(CurrentMemoryContext);
 
 			/*
-			 * If this was a transaction control statement, commit it and
-			 * arrange to start a new xact command for the next command
-			 * (if any).
+			 * If this was a transaction control statement or a variable
+			 * set/show/reset statement, commit it and arrange to start a
+			 * new xact command for the next command (if any).
 			 */
-			if (isTransactionStmt)
+			if (endTransactionBlock)
 			{
-				finish_xact_command(false);
+				finish_xact_command(true);
 				xact_started = false;
 			}
 		}						/* end loop over queries generated from a
@@ -844,19 +847,7 @@ pg_exec_query_string(StringInfo query_string,	/* string to execute */
 		 */
 		if (lnext(parsetree_item) == NIL && xact_started)
 		{
-			/*
-			 *	Don't allow SET/SHOW/RESET to start a new transaction
-			 *	with autocommit off.  We do this by forcing a COMMIT
-			 *	when these commands start a transaction.
-			 */
-			if (autocommit ||
-				IsTransactionState() ||
-				(strcmp(commandTag, "SET") != 0 &&
-				 strcmp(commandTag, "SHOW") != 0 &&
-				 strcmp(commandTag, "RESET") != 0))
 			finish_xact_command(false);
-			else
-				finish_xact_command(true);
 			xact_started = false;
 		}
 
@@ -1733,7 +1724,7 @@ PostgresMain(int argc, char *argv[], const char *username)
 	if (!IsUnderPostmaster)
 	{
 		puts("\nPOSTGRES backend interactive interface ");
-		puts("$Revision: 1.300 $ $Date: 2002/10/09 04:59:38 $\n");
+		puts("$Revision: 1.301 $ $Date: 2002/10/13 16:55:05 $\n");
 	}
 
 	/*