LDAP-Queries with wildcards (?) ...

[Tomas Hein <Tomas.Hein@amg.de>]

I use OpenLDAP 2.0.7 and i have following Problem :
 there are ca. 10000 User-Entries in the directory,
i have tested the following searchfilters
( 'user_id' is just an example ) :

1)   '(& (objectclass=inetOrgPerson) (uid=user_id) )'     ->
       the user is found

2)   '(& (objectclass=inetOrgPerson) (uid=*user_id*) )'  ->
       there are users, that are not found ( ca 6% of all users - WHY?)

3)   '(& (objectclass=inetOrgPerson) (uid=*user_id) )'    ->
      the  user is rapidly found

- Queries with wildcards at the begin and at the end (2) don't found all

users. ( UserId has the syntax 'user_xxx_St_xxx' e.g.:
  user 'user_7_St_205' is found and user 'user_15_St_160' not <both
entries exist in the directory!> ).

any ideas ?