Hello, I have inherited responsibility for a LDAP user management system written in Python/Django: https://github.com/VPAC/django-placard In my rewrite come across a sticky problem: how do I reliably and efficiently allocate unique uidNumber for new users and gidNumber of new groups? The current solution, as used by my predecessor, is to list every user or group in the system, sort or scan though the list looking for the highest id, add 1, and use that. Unfortunately, this seems to be lacking in efficiency (specially if there are a lot of users) and relying on the hope that two users will never be created at the same time. Race conditions could occur. Only solution I can think of is to create a special server that atomically allocates ids. Seems a lot of work for something so simple. Any ideas for other solutions? (not sure if this is on-topic or not for luv-main, so posting here just to be safe) Thanks -- Brian May <brian@microcomaustralia.com.au>