"Bob Phillips" wrote...
GUIDs?
....

Yes, for example. Banks and other high transaction count businesses also
have localized batching of IDs, in which local servers receive a batch of
IDs from a central machines. Those IDs are marked as distributed but not yet
used until those local machines replicate with the central machine and
transmit the IDs actually assigned. Depending on how many distributed but
not yet assigned IDs there are on the local server, the central machine may
or may not give the server another batch.

What I'm getting at is that real time centralization isn't necessary, but
eventual centralization during replication is necessary. Use the level of
centralization or localization that works best. Just don't forget to
replicate.