xtdb-v1 entity-history

entity-history.clj

; Add some sensor readings for sensor :a
(xt/submit-tx xtdb-node
  [; Day 1: You get a reading of 1
   [::xt/put
    {:xt/id :a :value 1}
    #inst "2024-01-01"]
   ; Day 2: You get a reading of 2
   [::xt/put
    {:xt/id :a :value 2}
    #inst "2024-01-02"]
   ; Day 3: You get a reading of 2 again
   [::xt/put
    {:xt/id :a :value 2}
    #inst "2024-01-03"]
   ; Day 4: You get a reading of 3
   [::xt/put
    {:xt/id :a :value 3}
    #inst "2024-01-04"]])

; Get the current value of :a
(xt/q (xt/db xtdb-node)
      '{:find [(pull doc [*])]
        :where [[doc :xt/id :a]]})
; => #{[{:xt/id :a, :value 3}]}

; How has :a changed over "valid time"?
(let [sensor :a]
  (->> (xt/entity-history (xt/db xtdb-node)
                          sensor
                          :asc
                          {:with-docs? true})
       (mapv ::xt/doc)))
; => [{:xt/id :a, :value 1}
;     {:xt/id :a, :value 2}
;     {:xt/id :a, :value 2}
;     {:xt/id :a, :value 3}]