-- # $Id$
-- # $HeadURL$
-- # $Author$

CREATE OR REPLACE FUNCTION exists_constraint(constraintName text, dbSchema text, constraintType char) RETURNS bool AS
$$
DECLARE
  exist_constraint "bool";

BEGIN

   EXECUTE 'SELECT COUNT(*)
            FROM   pg_class     c
            JOIN   pg_namespace n ON n.oid = c.relnamespace
            WHERE  c.relname = $1
            AND    n.nspname = $2
            AND    c.relkind = $3'
   INTO exist_constraint
   USING constraintName, dbSchema, constraintType; 

   IF exist_constraint THEN
      RETURN TRUE;
   ELSE                    
      RETURN FALSE;
   END IF;

END;
$$
LANGUAGE plpgsql;