Grid mobility: problem aspect

In addition to the topic about grid mobility .

The question arose: how will the user ID, who has just registered, be assigned to the system without centralization?

One of the reasons: to store the database of all IDs in the base of each point. Disadvantages: it will be very hard to update the database (on the scale of all users), and if several new users log in, updates on the ID may arise.
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Another option is to assign the ID "not immediately." When registering on the web, we take the nearest numbers and see which bits have already been accurately filled. If, say, there is a bit (32 in binary representation) number 32 in the neighborhood of the neighbors, then the ID starts at bit 33, the query marks "32nd is zero" and the request is passed to the next points. Where there is an absence of a filled discharge, the corresponding discharge is recorded in the ID.

I myself feel that the idea is crude, but it looks like the algorithm for catching a lion in Africa: we divide Africa in half, discard the one in which there is no lion, we repeat to catch ...