didn't know datomic was free of licensing fees - I didn't use it back in the day because the cost was prohibitive... interesting
And also it has inspired a few other clojure datalog databases, so there is much more choice: * https://github.com/datalevin/datalevin * https://github.com/replikativ/datahike * https://github.com/threatgrid/asami
There is also xtdb, but it abandoned datalog and is going in another (albeit interesting direction) https://xtdb.com/
here is a comparison website, but it is somewhat out of date: https://clojurelog.github.io/