Re: How to mark a transaction as SERIALIZABLE?

In version 9.0, I've been reading http://www.postgresql.org/docs/9.0/interactive/sql-begin.html. I've been using the following  : 

CREATE OR REPLACE FUNCTION test(character varying)

  RETURNS SETOF integer AS

$BODY$

BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE; 

--SET TRANSACTION ISOLATION LEVEL SERIALIZABLE; 

RETURN 1;

END;

 $BODY$

  LANGUAGE plpgsql VOLATILE

which returns with the error : 

ERROR:  syntax error at or near "TRANSACTION"

LINE 1: TRANSACTION ISOLATION LEVEL SERIALIZABLE

if the BEGIN line is empty with no semi-colon, the function will work :

CREATE OR REPLACE FUNCTION test(character varying)

  RETURNS integer AS

$BODY$

BEGIN 

--TRANSACTION ISOLATION LEVEL SERIALIZABLE; 

--SET TRANSACTION ISOLATION LEVEL SERIALIZABLE; 

RETURN 1;

END;

 $BODY$

  LANGUAGE plpgsql VOLATILE

but if I place a semi-colon after BEGIN (e.g. BEGIN;), I get the error :

ERROR:  syntax error at or near ";"

LINE 5: BEGIN; 

So any help you may be able to provide in the BEGIN syntax (or whatever I'm doing wrong) is greatly appreciated. Thanks!

   -Joe