SELECT TIMESTAMP WITH TIME ZONE 'epoch' + 1109796233 * INTERVAL '1 second';

CREATE OR REPLACE FUNCTION ts2int(timestamp without time zone) RETURNS int AS
$$
select extract('epoch' from $1)::integer;
$$ LANGUAGE SQL STRICT STABLE;

CREATE OR REPLACE FUNCTION int2ts(integer) RETURNS timestamp AS
$$
SELECT ( TIMESTAMP WITH TIME ZONE 'epoch' + $1 * INTERVAL '1second')::timestamp without time zone;
$$ LANGUAGE SQL STRICT STABLE;