CREATE OR REPLACE FUNCTION get_users_by_ids(_uids text[])
  RETURNS JSON AS
$func$
   SELECT json_agg(sub)
   FROM (
      SELECT u.id, u.username
           , ARRAY (SELECT followid FROM followers WHERE userid   = u.id) AS following
           , ARRAY (SELECT userid   FROM followers WHERE followid = u.id) AS followers
      FROM   users u
      WHERE  u.id = ANY (_uids)
      ) sub
$func$  LANGUAGE sql SECURITY DEFINER;