diff --git a/Database/Groundhog/Generic/PersistBackendHelpers.hs b/Database/Groundhog/Generic/PersistBackendHelpers.hs
--- a/Database/Groundhog/Generic/PersistBackendHelpers.hs
+++ b/Database/Groundhog/Generic/PersistBackendHelpers.hs
@@ -254,6 +254,7 @@
 
   let ifAbsent tname constr = do
       let query = "SELECT " <> maybe "1" id (constrId escape constr) <> " FROM " <> escape (fromString tname) <> " WHERE " <> cond
+--      x <- queryFunc query [DbInt64] (foldr ((.) . snd) id uniques []) id
       x <- queryFunc query [DbInt64] (concatMap snd uniques) id
       case x of
         Nothing  -> liftM Right $ Core.insert v
diff --git a/examples/compositeKeys.hs b/examples/compositeKeys.hs
new file mode 100644
--- /dev/null
+++ b/examples/compositeKeys.hs
@@ -0,0 +1,74 @@
+{-# LANGUAGE GADTs, TypeFamilies, TemplateHaskell, QuasiQuotes, FlexibleInstances, StandaloneDeriving #-}
+import Control.Monad
+import Control.Monad.IO.Class (liftIO)
+import Database.Groundhog.TH
+import Database.Groundhog.Sqlite
+
+-- artistName is a unique key
+data Artist = Artist { artistName :: String, artistSurname :: String } deriving (Eq, Show)
+
+mkPersist defaultCodegenConfig [groundhog|
+definitions:
+  - entity: Artist
+    autoKey:
+      constrName: AutoKey
+      default: false # Defines if this key is used when an entity is stored directly, for example, data Ref = Ref SomeEntity
+    keys:
+      - name: ArtistFullName
+        default: true
+    constructors:
+      - name: Artist
+        uniques:
+          - name: ArtistFullName
+            fields: [artistName, artistSurname]
+|]
+
+data Album  = Album  { albumName :: String} deriving (Eq, Show)
+-- many-to-many relation
+data ArtistAlbum = ArtistAlbum {artist :: Key Artist (Unique ArtistFullName), album :: Key Album BackendSpecific }
+deriving instance Eq ArtistAlbum
+deriving instance Show ArtistAlbum
+-- We cannot use regular deriving because when it works, the Key Eq and Show instances for (Key Album BackendSpecific) are not created yet
+data Track  = Track  { albumTrack :: Key Album BackendSpecific, trackName :: String }
+deriving instance Eq Track
+deriving instance Show Track
+
+mkPersist defaultCodegenConfig [groundhog|
+definitions:
+- entity: Album
+- entity: Track
+# keys of many-to-many relation form a unique key
+- entity: ArtistAlbum
+  autoKey: null
+  keys:
+  - name: ArtistAlbumKey
+    default: true
+  constructors:
+  - name: ArtistAlbum
+    fields:
+    - name: artist
+      embeddedType: []
+    uniques:
+    - name: ArtistAlbumKey
+      fields: [artist, album]
+|]
+
+main :: IO ()
+main = withSqliteConn ":memory:" $ runSqliteConn $ do
+  let artists = [Artist "John" "Lennon", Artist "George" "Harrison"]
+      imagineAlbum = Album "Imagine"
+  runMigration defaultMigrationLogger $ do
+    migrate (undefined :: ArtistAlbum)
+    migrate (undefined :: Track)
+  mapM_ insert artists
+
+  imagineKey <- insert imagineAlbum
+  let tracks = map (Track imagineKey) ["Imagine", "Crippled Inside", "Jealous Guy", "It's So Hard", "I Don't Want to Be a Soldier, Mama, I Don't Want to Die", "Gimme Some Truth", "Oh My Love", "How Do You Sleep?", "How?", "Oh Yoko!"]
+  mapM_ insert tracks
+  mapM_ (\artist -> insert $ ArtistAlbum (extractUnique artist) imagineKey) artists
+  -- print first 3 tracks from any album with John Lennon
+  [albumKey'] <- project AlbumField $ (ArtistField ==. ArtistFullNameKey "John" "Lennon") `limitTo` 1
+  -- order by primary key
+  tracks' <- select $ (AlbumTrackField ==. albumKey') `orderBy` [Asc AutoKeyField] `limitTo` 3
+  liftIO $ print tracks'
+
diff --git a/groundhog.cabal b/groundhog.cabal
--- a/groundhog.cabal
+++ b/groundhog.cabal
@@ -1,5 +1,5 @@
 name:            groundhog
-version:         0.1.0.1
+version:         0.1.0.2
 license:         BSD3
 license-file:    LICENSE
 author:          Boris Lykah <lykahb@gmail.com>
@@ -15,7 +15,7 @@
 
 library
     build-depends:   base                     >= 4         && < 5
-                   , bytestring               >= 0.9       && < 0.10
+                   , bytestring               >= 0.9
                    , transformers             >= 0.2.1     && < 0.4
                    , time                     >= 1.1.4
                    , text                     >= 0.8       && < 0.12