I'm making the switch to MongoDB from MySQL. A familiar architecture to me for a very basic users table would have auto-incrementing of the uid. See Mongo's own documentation for this use case.
I'm wondering whether this is the best architectural decision. From a UX standpoint, I like having UIDs as external references, for example in shorter URLs: http://example.com/users/12345
Is there a third way? Someone in IRC Freenode's #mongodb suggested creating a range of IDs and caching them. I'm unsure of how to actually implement that, or whether there's another route I can go. I don't necessarily even need the _id itself to be incremented this way. As long as the users all have a unique numerical uid within the document, I would be happy.