gistfile1.txt

;; same thing using reduction over d/datoms.
;; Objective is to avoid realizing too much in memory
;; May still be slow, but won't OOM

(defn orgs->max-fks [db]
  (reduce (fn [o->fk [content-eid _ content-fk]]
            (let [org-id (-> (d/entity db content-eid)
                          :content/collection
                          :collection/organization
                          :db/id)]
              ;; We know content-fk is always increasing,
              ;; so we just write over the previous seen
              (assoc o->fk org-id content-fk)))
    {}
    ;; You can skip over some of these with d/index-range if you know a
    ;; higher fk that all orgs have at least one fk above
    (d/datoms db :avet :content/fk)))