@magnars: I think I read that they are committed to supporting up to 100k partitions but there is no hard limit built in.

@magnars @domkm : I'd recommend instead creating say 1024 partitions or so and then assigning users somehow into those (maybe randomly, maybe doing a hash of some external id and using mod to chunk that into 1024 sections). Rich said a thing about this a long time ago on the mailing list (bottom post): https://groups.google.com/forum/#!searchin/datomic/rich$20hickey$20partition/datomic/7HvCCbrsOJ0/IOKsOMMcahsJ

Excellent, that makes sense. Thanks for the advice.