core.logic datomic query blog

bench.clj

(defn bench [n f]
  (let [rand-str #(str (java.util.UUID/randomUUID))
        emails (repeatedly n rand-str)
        name-email (reduce (fn [res em]
                             (conj res (vector (rand-str) (rand-str) em)))
                           [] emails)
        email-height (reduce (fn [res em]
                               (conj res (vector em (rand-int 100))))
                             [] emails)]
    (time (count (f name-email email-height)))))


(bench 5000 (partial q '[:find ?first ?height
                         :in [[?last ?first ?email]] [[?email ?height]]]))
;; "Elapsed time: 14757.248824 msecs"
;; 5000

(bench 5000 join-test)
;; "Elapsed time: 185.604 msecs"
;; 5000

;; Optimised Datomic query
(bench 5000 (partial q '[:find ?first ?height
                         :in $a $b
                         :where [$a ?last ?first ?email] [$b ?email ?height]]))
;; "Elapsed time: 10.869 msecs"
;; 5000

binding-map.clj

(binding-map '(?first ?last) ["John" "Doe"])
;; {?last "Doe", ?first "John"}

datomic-join.clj

(q '[:find ?first ?height
     :in [[?last ?first ?email]] [[?email ?height]]]
   [["Doe" "John" "[email protected]"]
    ["Doe" "Jane" "[email protected]"]]
   [["[email protected]" 73]
    ["[email protected]" 71]])
;; #<HashSet [["Jane" 73], ["John" 71]]>

join-test.clj

(defn join-test [xs ys]
  (let [rx (query '(?last ?first ?email) xs)
        ry (query '(?email ?height) ys)
        r (clojure.set/join rx ry)]
    (map (juxt '?first '?height) r)))

query.clj

(defn query [rule xs]  
  (let [prule (prep rule)]
    (map #(binding-map* prule (prep %)) xs)))

(query '(?answer) (repeatedly 5 #(vector 42)))
;; ({?answer 42} {?answer 42} {?answer 42} {?answer 42} {?answer 42})

run-join-test.clj

(join-test
 [["Doe" "John" "[email protected]"]
  ["Doe" "Jane" "[email protected]"]]
 [["[email protected]" 73]
  ["[email protected]" 71]])
;; (["John" 71] ["Jane" 73])