CREATE OR REPLACE FUNCTION insert_operations_trigger()
  RETURNS TRIGGER AS
$BODY$
    DECLARE
        SQL text;
        m RECORD;
        r macnoms.operations;
    BEGIN
        IF EXISTS (SELECT 1 FROM macnoms.operations WHERE opnum=NEW.opnum)  THEN
            SELECT INTO r * FROM macnoms.operations WHERE opnum=NEW.opnum;
            NEW.lastmod := NULL;
            r.lastmod:=NULL;
            IF ROW(r.*) IS DISTINCT FROM ROW(NEW.*) OR NOT(r.the_geom ~ NEW.the_geom AND st_equals(r.the_geom,NEW.the_geom)) THEN
                DELETE FROM macnoms.operations WHERE opnum=NEW.opnum;
            ELSE
                RETURN NULL;
            END IF;
        END IF;
        NEW.lastmod=now();
        RETURN NEW;
    END;
$BODY$
  LANGUAGE plpgsql VOLATILE
  COST 100;
ALTER FUNCTION insert_operations_trigger() OWNER TO pgsql;