CREATE OR REPLACE FUNCTION notify_event() RETURNS TRIGGER AS $$

    DECLARE
        data json;
        notification json;

    BEGIN

        -- Convert the old or new row to JSON, based on the kind of action.
        -- Action = DELETE?             -> OLD row
        -- Action = INSERT or UPDATE?   -> NEW row
        IF (TG_OP = 'DELETE') THEN
            data = row_to_json(OLD);
        ELSE
            data = row_to_json(NEW);
        END IF;

        -- Contruct the notification as a JSON string.
        notification = json_build_object(
                          'table',TG_TABLE_NAME,
                          'action', TG_OP,
                          'data', data);

        -- Execute pg_notify(channel, notification)
        PERFORM pg_notify('redify_update', notification::text);

        -- Result is ignored since this is an AFTER trigger
        RETURN NULL;
    END;

$$ LANGUAGE plpgsql;

CREATE TRIGGER products_notify_event
AFTER INSERT OR UPDATE OR DELETE ON products
    FOR EACH ROW EXECUTE PROCEDURE notify_event();