diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,7 @@
+## 2.5
+
+* changes for read/write typeclass split
+
 ## 2.1.4
 
 * support http-api-data for url serialization
diff --git a/Database/Persist/MongoDB.hs b/Database/Persist/MongoDB.hs
--- a/Database/Persist/MongoDB.hs
+++ b/Database/Persist/MongoDB.hs
@@ -7,7 +7,7 @@
 -- and want lower level-level MongoDB access.
 -- There are functions available to make working with the raw driver
 -- easier: they are under the Entity conversion section.
--- You should still use the same connection pool that you are using for Persistent. 
+-- You should still use the same connection pool that you are using for Persistent.
 --
 -- MongoDB is a schema-less database.
 -- The MongoDB Persistent backend does not help perform migrations.
@@ -173,7 +173,8 @@
     return $ lookup key env
 #endif
 
-instance HasPersistBackend DB.MongoContext DB.MongoContext where
+instance HasPersistBackend DB.MongoContext where
+    type BaseBackend DB.MongoContext = DB.MongoContext
     persistBackend = id
 
 recordTypeFromKey :: Key record -> record
@@ -187,21 +188,21 @@
     parseJSON (Number x) = (return . NoOrphanNominalDiffTime . fromRational . toRational) x
 
 
-#else 
+#else
     parseJSON (Number (I x)) = (return . NoOrphanNominalDiffTime . fromInteger) x
     parseJSON (Number (D x)) = (return . NoOrphanNominalDiffTime . fromRational . toRational) x
 
-#endif                           
+#endif
     parseJSON _ = fail "couldn't parse diff time"
 
 newtype NoOrphanPortID = NoOrphanPortID PortID deriving (Show, Eq)
 
 
 instance FromJSON NoOrphanPortID where
-#if MIN_VERSION_aeson(0, 7, 0)  
+#if MIN_VERSION_aeson(0, 7, 0)
     parseJSON (Number  x) = (return . NoOrphanPortID . PortNumber . fromIntegral ) cnvX
       where cnvX :: Word16
-            cnvX = round x 
+            cnvX = round x
 
 #else
     parseJSON (Number (I x)) = (return . NoOrphanPortID . PortNumber . fromInteger) x
@@ -376,7 +377,7 @@
 
 queryByKey :: (PersistEntity record, PersistEntityBackend record ~ DB.MongoContext)
            => Key record -> DB.Query
-queryByKey k = DB.select (keyToMongoDoc k) (collectionNameFromKey k)
+queryByKey k = (DB.select (keyToMongoDoc k) (collectionNameFromKey k)) {DB.project = projectionFromKey k}
 
 selectByKey :: (PersistEntity record, PersistEntityBackend record ~ DB.MongoContext)
             => Key record -> DB.Selection
@@ -540,10 +541,11 @@
 
 -- | older versions versions of haddock (like that on hackage) do not show that this defines
 -- @BackendKey DB.MongoContext = MongoKey { unMongoKey :: DB.ObjectId }@
-instance PersistStore DB.MongoContext where
+instance PersistCore DB.MongoContext where
     newtype BackendKey DB.MongoContext = MongoKey { unMongoKey :: DB.ObjectId }
         deriving (Show, Read, Eq, Ord, PersistField)
 
+instance PersistStoreWrite DB.MongoContext where
     insert record = DB.insert (collectionName record) (toInsertDoc record)
                 >>= keyFrom_idEx
 
@@ -571,16 +573,6 @@
         , DB.selector = keyToMongoDoc k
         }
 
-    get k = do
-            d <- DB.findOne (queryByKey k)
-            case d of
-              Nothing -> return Nothing
-              Just doc -> do
-                Entity _ ent <- fromPersistValuesThrow t doc
-                return $ Just ent
-          where
-            t = entityDefFromKey k
-
     update _ [] = return ()
     update key upds =
         DB.modify
@@ -588,9 +580,7 @@
            $ updatesToDoc upds
 
     updateGet key upds = do
-        result <- DB.findAndModify (DB.select (keyToMongoDoc key)
-                     (collectionNameFromKey key)
-                   ) (updatesToDoc upds)
+        result <- DB.findAndModify (queryByKey key) (updatesToDoc upds)
         either err instantiate result
       where
         instantiate doc = do
@@ -599,11 +589,21 @@
         err msg = Trans.liftIO $ throwIO $ KeyNotFound $ show key ++ msg
         t = entityDefFromKey key
 
+instance PersistStoreRead DB.MongoContext where
+    get k = do
+            d <- DB.findOne (queryByKey k)
+            case d of
+              Nothing -> return Nothing
+              Just doc -> do
+                Entity _ ent <- fromPersistValuesThrow t doc
+                return $ Just ent
+          where
+            t = entityDefFromKey k
 
-instance PersistUnique DB.MongoContext where
+instance PersistUniqueRead DB.MongoContext where
     getBy uniq = do
         mdoc <- DB.findOne $
-          DB.select (toUniquesDoc uniq) (collectionName rec)
+          (DB.select (toUniquesDoc uniq) (collectionName rec)) {DB.project = projectionFromRecord rec}
         case mdoc of
             Nothing -> return Nothing
             Just doc -> liftM Just $ fromPersistValuesThrow t doc
@@ -611,6 +611,7 @@
         t = entityDef $ Just rec
         rec = dummyFromUnique uniq
 
+instance PersistUniqueWrite DB.MongoContext where
     deleteBy uniq =
         DB.delete DB.Select {
           DB.coll = collectionName $ dummyFromUnique uniq
@@ -649,8 +650,8 @@
         instantiate (Just doc) =
             fromPersistValuesThrow (entityDef $ Just newRecord) doc
             -}
-   
 
+
 -- | It would make more sense to call this _id, but GHC treats leading underscore in special ways
 id_ :: T.Text
 id_ = "_id"
@@ -673,8 +674,21 @@
                       => Key record -> Text
 collectionNameFromKey = collectionName . recordTypeFromKey
 
+projectionFromEntityDef :: EntityDef -> DB.Projector
+projectionFromEntityDef eDef =
+  map toField (entityFields eDef)
+  where
+    toField :: FieldDef -> DB.Field
+    toField fDef = (unDBName (fieldDB fDef)) DB.=: (1 :: Int)
 
-instance PersistQuery DB.MongoContext where
+projectionFromKey :: PersistEntity record => Key record -> DB.Projector
+projectionFromKey = projectionFromEntityDef . entityDefFromKey
+
+projectionFromRecord :: PersistEntity record => record -> DB.Projector
+projectionFromRecord = projectionFromEntityDef . entityDef . Just
+
+
+instance PersistQueryWrite DB.MongoContext where
     updateWhere _ [] = return ()
     updateWhere filts upds =
         DB.modify DB.Select {
@@ -688,6 +702,7 @@
         , DB.selector = filtersToDoc filts
         }
 
+instance PersistQueryRead DB.MongoContext where
     count filts = do
         i <- DB.count query
         return $ fromIntegral i
@@ -758,6 +773,7 @@
       DB.limit = fromIntegral limit
     , DB.skip  = fromIntegral offset
     , DB.sort  = orders
+    , DB.project = projectionFromRecord (dummyFromFilts filts)
     }
   where
     (limit, offset, orders') = limitOffsetOrder opts
@@ -914,7 +930,7 @@
 
 
 fromPersistValuesThrow :: (Trans.MonadIO m, PersistEntity record, PersistEntityBackend record ~ DB.MongoContext) => EntityDef -> [DB.Field] -> m (Entity record)
-fromPersistValuesThrow entDef doc = 
+fromPersistValuesThrow entDef doc =
     case eitherFromPersistValues entDef doc of
         Left t -> Trans.liftIO . throwIO $ PersistMarshalError $
                    unHaskellName (entityHaskell entDef) `mappend` ": " `mappend` t
@@ -960,14 +976,14 @@
     -- reorder = map (fromJust . (flip Prelude.lookup $ castDoc)) castColumns
     --
     -- this is O(n * log(n))
-    -- reorder =  map (\c -> (M.fromList castDoc) M.! c) castColumns 
+    -- reorder =  map (\c -> (M.fromList castDoc) M.! c) castColumns
     --
     -- and finally, this is O(n * log(n))
     -- * do an alist lookup for each column
     -- * but once we found an item in the alist use a new alist without that item for future lookups
     -- * so for the last query there is only one item left
     --
-    reorder :: [(Text, PersistValue)] 
+    reorder :: [(Text, PersistValue)]
     reorder = match castColumns castDoc []
       where
         match :: [(Text, Maybe EmbedEntityDef)]
@@ -979,7 +995,6 @@
         -- allow extra mongoDB fields that persistent does not know about
         -- another application may use fields we don't care about
         -- our own application may set extra fields with the raw driver
-        -- TODO: instead use a projection to avoid network overhead
         match [] _ values = values
         match (column:columns) fields values =
           let (found, unused) = matchOne fields []
@@ -1060,7 +1075,7 @@
   cast' (DB.RegEx (DB.Regex us1 us2))    = Just $ PersistByteString $ E.encodeUtf8 $ T.append us1 us2
   cast' (DB.Doc doc)  = Just $ PersistMap $ assocListFromDoc doc
   cast' (DB.Array xs) = Just $ PersistList $ mapMaybe DB.cast' xs
-  cast' (DB.ObjId x)  = Just $ oidToPersistValue x 
+  cast' (DB.ObjId x)  = Just $ oidToPersistValue x
   cast' (DB.JavaScr _) = throw $ PersistMongoDBUnsupported "cast operation not supported for javascript"
   cast' (DB.Sym _)     = throw $ PersistMongoDBUnsupported "cast operation not supported for sym"
   cast' (DB.Stamp _)   = throw $ PersistMongoDBUnsupported "cast operation not supported for stamp"
@@ -1078,7 +1093,7 @@
 
   get = do w1 <- Serialize.get
            w2 <- Serialize.get
-           return (DB.Oid w1 w2) 
+           return (DB.Oid w1 w2)
 
 dummyFromUnique :: Unique v -> v
 dummyFromUnique _ = error "dummyFromUnique"
diff --git a/persistent-mongoDB.cabal b/persistent-mongoDB.cabal
--- a/persistent-mongoDB.cabal
+++ b/persistent-mongoDB.cabal
@@ -1,5 +1,5 @@
 name:            persistent-mongoDB
-version:         2.1.4
+version:         2.5
 license:         MIT
 license-file:    LICENSE
 author:          Greg Weber <greg@gregweber.info>
@@ -20,7 +20,7 @@
 
 library
     build-depends:   base               >= 4.6 && < 5
-                   , persistent         >= 2.1.1   && < 3
+                   , persistent         >= 2.5   && < 3
                    , text               >= 0.8
                    , transformers       >= 0.2.1
                    , containers         >= 0.2