[Samba] idmap_rid/idmap_hash collisions?

[Nick]

Is it possible for the uid/gid numbers that are generated by the
idmap_rid and idmap_hash to collide if there are a large number of
users or groups?  I cannot seem to find any documentation on the
limitations of these plugins.  Before using I want to make absolutely
sure that there won't be any collisions.

In doing some research about Likewise Open, I see it's hashing routine
can have this problem:

"If your Active Directory relative identifiers, or RIDs, are a number
greater than 524,287, the Likewise Open algorithm that generates UIDs
and GIDs can result in UID-GID collisions among users and groups. In
such cases, it is recommended that you use Likewise Enterprise or that
you use the Likewise UID-GID management tool."

http://www.likewise.com/resources/documentation_library/manuals/open/likewise-open-guide.html#AboutLikewiseAgent

I was somehow thinking that Likewise is based on Samba, although I
don't remember where I heard that so it could be total BS.

Does anyone know about the limitations of these idmap backends?