Added: d/reset-schema!, d/with-schema

Author: tonsky

CHANGELOG.md

@@ -1,5 +1,6 @@
 # WIP
 
+- Added: `d/reset-schema!`, `d/with-schema`
 - JVM: Return `nil` from `d/restore-conn` if there is no db
 - Do not throw from d/touch when finding hanging refs
 

src/datascript/core.cljc

@@ -285,6 +285,10 @@
   {:pre [(db/db? db)]}
   (:db-after (with db tx-data)))
 
+(defn ^DB with-schema
+  "Warning! No validation or conversion. Only change schema in a compatible way"
+  [db schema]
+  (db/with-schema db schema))
 
 ; Index lookups
 
@@ -527,7 +531,7 @@
            (if (> (transduce (map count) + 0 tx-tail') (:branching-factor settings))
              ;; overflow tail
              (do
-               (storage/store-impl! db (storage/storage-adapter db))
+               (storage/store-impl! db (storage/storage-adapter db) false)
                (reset! *tx-tail [])
                (reset! (:db-last-stored (meta conn)) db))
              ;; just update tail
@@ -652,6 +656,17 @@
        (callback report))
      db)))
 
+(defn reset-schema! [conn schema]
+  "Warning! Does not perform any validation or data conversion. Only change schema in a compatible way"
+  {:pre [(conn? conn)]}
+  (let [db (swap! conn db/with-schema schema)]
+    #?(:clj
+       (when-some [storage (storage/storage @conn)]
+         (storage/store-impl! db (storage/storage-adapter db) true)
+         (reset! (:tx-tail (meta conn)) [])
+         (reset! (:db-last-stored (meta conn)) db)))
+    db))
+
 (defn- atom? [a]
   #?(:cljs (instance? Atom a)
      :clj  (instance? clojure.lang.IAtom a)))

src/datascript/db.cljc

@@ -1032,6 +1032,15 @@
      :pull-attrs    (lru/cache 100)
      :hash          (atom 0)}))
 
+(defn with-schema [db schema]
+  {:pre [(db? db) (or (nil? schema) (map? schema))]}
+  (assoc db
+    :schema        schema
+    :rschema       (rschema (merge implicit-schema schema))
+    :pull-patterns (lru/cache 100)
+    :pull-attrs    (lru/cache 100)
+    :hash          (atom 0)))
+
 (defn- equiv-db-index [x y]
   (loop [xs (seq x)
          ys (seq y)]

src/datascript/storage.clj

@@ -52,6 +52,7 @@
   me.tonsky.persistent_sorted_set.IStorage
   (store [_ ^ANode node]
     (let [addr (gen-addr)
+          _    (util/log "store" addr)
           keys (mapv serializable-datom (.keys node))
           data (cond-> {:level (.level node)
                         :keys  keys}
@@ -60,6 +61,7 @@
       (vswap! *store-buffer* conj! [addr data])
       addr))
   (restore [_ addr]
+    (util/log "restore" addr)
     (let [{:keys [level keys addresses]} (-restore storage addr)
           ^List keys' (map (fn [[e a v tx]] (db/datom e a v tx)) keys)]
       (if addresses
@@ -84,7 +86,7 @@
 (defn- remember-db [db]
   (.add stored-dbs (WeakReference. db)))
 
-(defn store-impl! [db adapter]
+(defn store-impl! [db adapter force?]
   (locking (:storage adapter)
     (remember-db db)
     (binding [*store-buffer* (volatile! (transient []))]
@@ -100,7 +102,7 @@
                     :avet     avet-addr
                     :max-addr @*max-addr}
                    (set/settings (:eavt db)))]
-        (when (pos? (count @*store-buffer*))
+        (when (or force? (pos? (count @*store-buffer*)))
           (vswap! *store-buffer* conj! [root-addr meta])
           (vswap! *store-buffer* conj! [tail-addr []])
           (-store (:storage adapter) (persistent! @*store-buffer*)))
@@ -109,17 +111,17 @@
 (defn store
   ([db]
    (if-some [adapter (storage-adapter db)]
-     (store-impl! db adapter)
+     (store-impl! db adapter false)
      (throw (ex-info "Database has no associated storage" {}))))
   ([db storage]
    (if-some [adapter (storage-adapter db)]
      (let [current-storage (:storage adapter)]
        (if (identical? current-storage storage)
-         (store-impl! db adapter)
+         (store-impl! db adapter false)
          (throw (ex-info "Database is already stored with another IStorage" {:storage current-storage}))))
      (let [settings (.-_settings ^PersistentSortedSet (:eavt db))
            adapter  (StorageAdapter. storage settings)]
-       (store-impl! db adapter)))))
+       (store-impl! db adapter false)))))
 
 (defn store-tail [db tail]
   (-store (storage db) [[tail-addr (mapv #(mapv serializable-datom %) tail)]]))