The attached patch implements START TRANSACTION, per SQL99. The

functionality of the command is basically identical to that of
BEGIN; it just accepts a few extra options (only one of which
PostgreSQL currently implements), and is standards-compliant.
The patch includes a simple regression test and documentation.

[ Regression tests removed, per Peter.]

Neil Conway

doc/src/sgml/ref/allfiles.sgml

 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/ref/allfiles.sgml,v 1.43 2002/07/29 22:14:10 tgl Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/ref/allfiles.sgml,v 1.44 2002/08/04 04:31:44 momjian Exp $
 PostgreSQL documentation
 Complete list of usable sgml source files in this directory.
 -->
@@ -113,6 +113,7 @@ Complete list of usable sgml source files in this directory.
 <!entity setSessionAuth     system "set_session_auth.sgml">
 <!entity setTransaction     system "set_transaction.sgml">
 <!entity show               system "show.sgml">
+<!entity startTransaction	system "start_transaction.sgml">
 <!entity truncate           system "truncate.sgml">
 <!entity unlisten           system "unlisten.sgml">
 <!entity update             system "update.sgml">

doc/src/sgml/ref/begin.sgml

 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/ref/begin.sgml,v 1.17 2002/04/21 19:02:39 thomas Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/ref/begin.sgml,v 1.18 2002/08/04 04:31:44 momjian Exp $
 PostgreSQL documentation
 -->
 
@@ -21,7 +21,7 @@ PostgreSQL documentation
   <refsynopsisdivinfo>
    <date>1999-07-20</date>
   </refsynopsisdivinfo>
-  <synopsis>  
+  <synopsis>
 BEGIN [ WORK | TRANSACTION ]
   </synopsis>
   

doc/src/sgml/ref/set_transaction.sgml

-<!-- $Header: /cvsroot/pgsql/doc/src/sgml/ref/set_transaction.sgml,v 1.8 2002/01/20 22:19:57 petere Exp $ -->
+<!-- $Header: /cvsroot/pgsql/doc/src/sgml/ref/set_transaction.sgml,v 1.9 2002/08/04 04:31:44 momjian Exp $ -->
 <refentry id="SQL-SET-TRANSACTION">
  <docinfo>
   <date>2000-11-24</date>
@@ -97,11 +97,11 @@ SET default_transaction_isolation = '<replaceable>value</replaceable>'
    <title>SQL92, SQL99</title>
 
    <para>
-    SERIALIZABLE is the default level in <acronym>SQL</acronym>.
-    <productname>PostgreSQL</productname> does not provide the
-    isolation levels <option>READ UNCOMMITTED</option> 
-    and <option>REPEATABLE READ</option>. Because
-    of multiversion concurrency control, the serializable level is not
+    <option>SERIALIZABLE</option> is the default level in
+    <acronym>SQL</acronym>.  <productname>PostgreSQL</productname> does
+    not provide the isolation levels <option>READ UNCOMMITTED</option> 
+    and <option>REPEATABLE READ</option>. Because of multiversion
+    concurrency control, the <option>SERIALIZABLE</option> level is not
     truly serializable. See the <citetitle>User's Guide</citetitle> for
     details.
    </para>

doc/src/sgml/reference.sgml

 <!-- reference.sgml
-$Header: /cvsroot/pgsql/doc/src/sgml/reference.sgml,v 1.32 2002/07/29 22:14:10 tgl Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/reference.sgml,v 1.33 2002/08/04 04:31:44 momjian Exp $
 
 PostgreSQL Reference Manual
 -->
@@ -122,6 +122,7 @@ PostgreSQL Reference Manual
    &setSessionAuth;
    &setTransaction;
    &show;
+   &startTransaction;
    &truncate;
    &unlisten;
    &update;

src/backend/nodes/copyfuncs.c

@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.198 2002/07/29 22:14:10 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.199 2002/08/04 04:31:44 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2226,6 +2226,7 @@ _copyTransactionStmt(TransactionStmt *from)
 	TransactionStmt *newnode = makeNode(TransactionStmt);
 
 	newnode->command = from->command;
+	Node_Copy(from, newnode, options);
 
 	return newnode;
 }

src/backend/nodes/equalfuncs.c

@@ -20,7 +20,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/equalfuncs.c,v 1.145 2002/07/29 22:14:10 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/equalfuncs.c,v 1.146 2002/08/04 04:31:44 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1055,6 +1055,8 @@ _equalTransactionStmt(TransactionStmt *a, TransactionStmt *b)
 {
 	if (a->command != b->command)
 		return false;
+	if (!equal(a->options, b->options))
+		return false;
 
 	return true;
 }

src/backend/parser/gram.y

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.352 2002/07/31 17:19:51 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.353 2002/08/04 04:31:44 momjian Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -195,7 +195,7 @@ static void doNegateFloat(Value *v);
 
 %type <str>		opt_id,	all_Op, MathOp, opt_name, SpecialRuleRelation
 
-%type <str>		opt_level, opt_encoding
+%type <str>		iso_level, opt_encoding
 %type <node>	grantee
 %type <list>	grantee_list
 %type <ival>	privilege
@@ -218,7 +218,7 @@ static void doNegateFloat(Value *v);
 				target_list, update_target_list, insert_column_list,
 				insert_target_list, def_list, opt_indirection,
 				group_clause, TriggerFuncArgs, select_limit,
-				opt_select_limit, opclass_item_list
+				opt_select_limit, opclass_item_list, trans_options
 
 %type <range>	into_clause, OptTempTableName
 
@@ -847,14 +847,14 @@ set_rest:  ColId TO var_list_or_default
 						n->args = makeList1($3);
 					$$ = n;
 				}
-			| TRANSACTION ISOLATION LEVEL opt_level opt_mode
+			| TRANSACTION ISOLATION LEVEL iso_level opt_mode
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);
 					n->name = "TRANSACTION ISOLATION LEVEL";
 					n->args = makeList1(makeStringConst($4, NULL));
 					$$ = n;
 				}
-			| SESSION CHARACTERISTICS AS TRANSACTION ISOLATION LEVEL opt_level
+			| SESSION CHARACTERISTICS AS TRANSACTION ISOLATION LEVEL iso_level
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);
 					n->name = "default_transaction_isolation";
@@ -902,7 +902,7 @@ var_value:	opt_boolean
 				{ $$ = makeAConst($1); }
 		;
 
-opt_level:	READ COMMITTED							{ $$ = "read committed"; }
+iso_level:	READ COMMITTED							{ $$ = "read committed"; }
 			| SERIALIZABLE							{ $$ = "serializable"; }
 		;
 
@@ -3445,67 +3445,60 @@ TransactionStmt:
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->command = ROLLBACK;
+					n->options = NIL;
 					$$ = (Node *)n;
 				}
 			| BEGIN_TRANS opt_trans
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->command = BEGIN_TRANS;
+					n->options = NIL;
 					$$ = (Node *)n;
 				}
-			| COMMIT opt_trans
+			| START TRANSACTION trans_options
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
-					n->command = COMMIT;
+					n->command = START;
+					n->options = $3;
 					$$ = (Node *)n;
 				}
-			| COMMIT opt_trans opt_chain
+			| COMMIT opt_trans
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->command = COMMIT;
+					n->options = NIL;
 					$$ = (Node *)n;
 				}
 			| END_TRANS opt_trans
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->command = COMMIT;
+					n->options = NIL;
 					$$ = (Node *)n;
 				}
 			| ROLLBACK opt_trans
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->command = ROLLBACK;
-					$$ = (Node *)n;
-				}
-			| ROLLBACK opt_trans opt_chain
-				{
-					TransactionStmt *n = makeNode(TransactionStmt);
-					n->command = ROLLBACK;
+					n->options = NIL;
 					$$ = (Node *)n;
 				}
 		;
 
+trans_options:	ISOLATION LEVEL iso_level
+									{ $$ = makeList1(makeStringConst($3, NULL)); }
+			 |	/* EMPTY */			{ $$ = NIL; }
+			 ;
+
 opt_trans:	WORK									{}
 			| TRANSACTION							{}
 			| /*EMPTY*/								{}
 		;
 
-opt_chain:	AND NO CHAIN							{}
-			| AND CHAIN
-				{
-					/* SQL99 asks that conforming dbs reject AND CHAIN
-					 * if they don't support it. So we can't just ignore it.
-					 * - thomas 2000-08-06
-					 */
-					elog(ERROR, "COMMIT/AND CHAIN not yet supported");
-				}
-		;
-
-
 /*****************************************************************************
  *
  *		QUERY:
- *				define view <viewname> '('target-list ')' [where <quals> ]
+ *				create view <viewname> '('target-list ')' AS <query>
  *
  *****************************************************************************/
 

src/backend/tcop/postgres.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.276 2002/07/30 16:55:45 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.277 2002/08/04 04:31:44 momjian Exp $
  *
  * NOTES
  *	  this is the "main" module of the postgres backend and
@@ -1693,7 +1693,7 @@ PostgresMain(int argc, char *argv[], const char *username)
 	if (!IsUnderPostmaster)
 	{
 		puts("\nPOSTGRES backend interactive interface ");
-		puts("$Revision: 1.276 $ $Date: 2002/07/30 16:55:45 $\n");
+		puts("$Revision: 1.277 $ $Date: 2002/08/04 04:31:44 $\n");
 	}
 
 	/*
@@ -2160,6 +2160,10 @@ CreateCommandTag(Node *parsetree)
 						tag = "BEGIN";
 						break;
 
+					case START:
+						tag = "START TRANSACTION";
+						break;
+
 					case COMMIT:
 						tag = "COMMIT";
 						break;

src/backend/tcop/utility.c

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/tcop/utility.c,v 1.167 2002/07/30 16:55:45 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/tcop/utility.c,v 1.168 2002/08/04 04:31:44 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -205,6 +205,28 @@ ProcessUtility(Node *parsetree,
 						BeginTransactionBlock();
 						break;
 
+					/*
+					 * START TRANSACTION, as defined by SQL99: Identical to BEGIN,
+					 * except that it takes a few additional options.
+					 */
+					case START:
+						{
+							BeginTransactionBlock();
+
+							/*
+							 * Currently, the only option that can be set is
+							 * the transaction isolation level by START
+							 * TRANSACTION.
+							 */
+							if (stmt->options)
+							{
+								SetPGVariable("TRANSACTION ISOLATION LEVEL",
+											  stmt->options,
+											  false);
+							}
+						}
+						break;
+
 					case COMMIT:
 						EndTransactionBlock();
 						break;

src/include/nodes/parsenodes.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: parsenodes.h,v 1.196 2002/07/30 16:55:45 momjian Exp $
+ * $Id: parsenodes.h,v 1.197 2002/08/04 04:31:44 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1387,13 +1387,14 @@ typedef struct UnlistenStmt
 } UnlistenStmt;
 
 /* ----------------------
- *		{Begin|Abort|End} Transaction Statement
+ *		{Begin|Commit|Rollback} Transaction Statement
  * ----------------------
  */
 typedef struct TransactionStmt
 {
 	NodeTag		type;
-	int			command;		/* BEGIN|END|ABORT */
+	int			command;		/* BEGIN_TRANS|START|COMMIT|ROLLBACK */
+	List	   *options;
 } TransactionStmt;
 
 /* ----------------------