How check result is still valid

[Tilo Lutz <TiloLutz@gmx.de>]

Hi

I have a small problem, with ldap and php and hope someone can help me.
For performance-reasons I want to cache ldap search results.
Is there any way openldap can inform me a search result is invalid?

Example:
I want to write a php-application to manage users stored in ldap.
If a new user is created I'll check all assigned UIDNumber to get
a free UIDNumber.
I want to cache all UIDNumbers but how can I check somebody
has changed anything without doing a new search?

Regards, Tilo