Not sure what channel to put this is, apologies if this not the one. One thing I really like about Datomic and it’s derivatives is that one can use multiple fact sources in queries. And also that one can use both databases and collections of facts as sources. What I’ve been thinking would also be nice is using SQL databases as sources. I imagine one could query them in a similar way where the entity position is the rowid and the attribute is :table-name/column-name . So an example from Datomics documentation would be:

[:find ?release-name
 :in $ ?artist-name
 :where [?artist-rowid :artist/name ?artist-name]
        [?release-rowid :release/artists ?artist-rowid]
        [?release-rowid :release/name ?release-name]]