Remove Invalid Characters (which are not accepted by Redshift)

remove_invalid_characters.sql

drop function if exists transformation_utils.remove_invalid_characters (p_string text);
create or replace function transformation_utils.remove_invalid_characters (p_string text)
  returns text AS
$body$ 
declare 
    c text;
begin
    select replace(p_string,'�','') into c;
    return c;
end;
$body$
  language 'plpgsql';