I have a column named position with geo data.
Query:

    SELECT ST_SRID(position) FROM checkpoint LIMIT 1;

returns 4326

If I try to simplify/compress points with 

    SELECT st_dumppoints(st_simplify(st_makeline(points.position)), 0.005))).geom
    FROM 
        (SELECT position
        FROM checkpoint) AS points

it works, but my question is, is st_simplify SRID aware function? Or should I transform the points to another coordinate system with ST_Transform? (The function probably reduces the number of nodes based on line section angles and the simplification may not give the correct results if it does not acknowledge lat lon coordinates - lat : lon ratio is not 1, which is the case with x and y from Cartesian coordinate system).