CREATE USER system privilege?

Hi

I wanted to create a user who can create other users. But this causes
some problems:

* I did not find any CREATE USER system privilege. So I have to create
the first user as Superuser? What I do not want!
--> Is this correct?

* So I decided to write a function owned by a superuser which can be
called by this first user (see below).
--> Why does CREATE USER $1 fail??? CREATE USER xyz works. Is this a bug
or did I miss something?

* Is there realy no other way to execute a stored procedure than SELECT
function();
--> I was looking about half an hours into the documents but did not
find something like: exec function();

Thanks for tipps
Oli

CREATE OR REPLACE FUNCTION
public.create_user(pg_catalog.pg_user.usename%TYPE)
RETURNS varchar AS '
DECLARE
  ret VARCHAR;
BEGIN
  CREATE USER oli;
  SELECT INTO ret $1;
  CREATE USER $1;
  RETURN ret;
END;
' LANGUAGE plpgsql
SECURITY DEFINER;

-------------------------------------------------------

Oli Sennhauser
Database-Engineer (Oracle & PostgreSQL)
Rebenweg 6
CH - 8610 Uster / Switzerland

Phone (+41) 1 940 24 82 or Mobile (+41) 79 450 49 14
e-Mail oli.sennhauser@bluewin.ch
Website http://mypage.bluewin.ch/shinguz/PostgreSQL/

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