The \'Embedded\' section of the Datomic Queries and Rules document says:
Query languages like SQL are oriented around a client-server model where, in a
datomic.api/entity provides such functionality.
It just has the gotcha that the returned map has a custom representation which hides all fields but :db/id. One can access those fields, but printing them requires merging the map into a regular Clojure map.
:db/id