Re: Uniqueness of entryUUID across multiple LDAP servers

[Michael Ströder <michael@stroeder.com>]

Rakesh Yadav wrote:
> Actually i am using multiple LDAP servers due to distributed environment.
> So our tree hierarchy can span over multiple LDAP servers.
>
> And i want to use entryUUID as a unique key for my entries of the tree.
> Can u tell me,entryUUID would be unique over multiple LDAP servers?
>
> Or in case of multiple LDAP servers, Two entries which are residing on 
> different LDAP servers but belongs to the same Tree Hierarchy, can have 
> same entryUUID?

Well, you have to clearly specify what that really means.

UUIDs are a general concept for generating unique IDs over time and 
space. But nothing prevents you to undermine the uniqueness by false 
administration. And still how UUIDs are used in a certain context is 
important for saying something about the scope of uniqueness.

In case of OpenLDAP's slapd it's more meaningful to describe when the 
entryUUID is / is not generated by the DSA:

1. If you add a new entry via LDAP to a LDAP server a new entryUUID is 
generated. (Use of a DUA like ldapadd or another LDAP client tool)

2. If you add a new entry with slapadd tool a new entryUUID is generated 
if the LDIF input data does *not* already contain entryUUID attribute. 
(e.g. when loading initial data from off-site generated LDIF)

3. If you (re-)add a new entry with slapadd tool the entryUUID attribute 
value is not generated if the LDIF input data already contains an 
entryUUID attribute (backup/restore case).

4. If an entry is replicated to another slapd server instance the 
attribute entryUUID is copied to the replicated entry, so no new entry 
UUID is generated! (normal replication via syncrepl)

If there are more cases I'd ask other readers to add to this list.

Ciao, Michael.


--
Michael Ströder
E-Mail: michael@stroeder.com
http://www.stroeder.com