Clojurians Log v2

I think that would usually be a job for a foreign key, right? Like a unique UUID that gets asserted on an entity separately from the automatically generated entity id? I think database generated identifiers like the entity id are only good for establishing relationships within the context of THAT specific DB. They often change, like when restoring databases from backups, so using them in other contexts can create problems if one database expects the ID to be a certain value, and then it changes.

I don't understand that answer to my question...

As I understood your original question, you were asking whether you could use the same Datomic-generated entity ID across two or more separate "systems". These kinds of automatically generated database identifier keys often change, so they're not good for establishing relationships between entities across systems

;; database one
{:db/id 123
 :event/uuid #uuid "680fea81-d130-4b06-bb25-ad034518b082"
 :event/date "04-28-2025"
 :event/name "Monday meeting"}

;; database two, holds a reference to the first entity in the first DB using its
;; :db/id
;; works, but the :db/id for this entity could change in the future, breaking
;; the foreign key reference
{:db/id 456
 :other-db/id 123
 :event/date "04-28-2025"
 :event/name "Monday meeting"}

;; database three, holds a reference to the first entity in the first DB using
;; its :event/uuid key
;; :event/uuid was asserted on this entity by the application itself, not by
;; Datomic, so it will persist between backups, restorations, etc.
{:db/id 456
 :other-db/uuid #uuid "680fea81-d130-4b06-bb25-ad034518b082"
 :event/date "04-28-2025"
 :event/name "Monday meeting"}