TRIGGER: clear old data on INSERT

trigger.sql

CREATE OR REPLACE FUNCTION clearOld()
RETURNS TRIGGER
AS $$
    BEGIN
        DELETE FROM sf_muni_points WHERE created_at < now()-'1 day'::interval;
        RETURN NEW;
    END;
$$ language plpgsql;

CREATE TRIGGER clearOldOnInsert
    AFTER INSERT ON sf_muni_points
    FOR EACH STATEMENT
    WHEN (pg_trigger_depth() = 0)
    EXECUTE PROCEDURE clearOld();