diff --git a/src/Database/Oracle/Simple/Internal.hs b/src/Database/Oracle/Simple/Internal.hs
index 9c1ab23..7756a15 100644
--- a/src/Database/Oracle/Simple/Internal.hs
+++ b/src/Database/Oracle/Simple/Internal.hs
@@ -12,7 +12,17 @@
 {- HLINT ignore "Avoid restricted function" -}
 
 module Database.Oracle.Simple.Internal
-  ( DPINativeType (..),
+  ( DPIContextCreateParams (..),
+    DPIIntervalYM(..),
+    DPIIntervalDS (..),
+    DPICreateMode (..),
+    DPIShardingKeyColumn (..),
+    DPIPurity (..),
+    DPIAuthMode (..),
+    ConnectionCreateParams (..),
+    DPIPoolGetMode (..),
+    DPIAppContext (..),
+    DPINativeType (..),
     DPIData (..),
     DPIBytes (..),
     DPIStmt (..),
@@ -80,7 +90,7 @@ import Foreign.C.String (CString, newCString, newCStringLen, peekCString, peekCS
 import Foreign.C.Types (CInt (..), CUInt (..))
 import Foreign.ForeignPtr (ForeignPtr, addForeignPtrFinalizer, finalizeForeignPtr, newForeignPtr_, withForeignPtr)
 import Foreign.Marshal.Alloc (alloca, free)
-import Foreign.Ptr (FunPtr, Ptr, castPtr, nullPtr)
+import Foreign.Ptr (FunPtr, Ptr, castPtr, nullPtr, plusPtr)
 import Foreign.Storable.Generic (GStorable, Storable (..))
 import GHC.Generics (Generic)
 import GHC.TypeLits (Natural)
@@ -326,8 +336,126 @@ data DPIPoolCreateParams = DPIPoolCreateParams
   , dpi_accessTokenCallback :: FunPtr ()
   , dpi_accessTokenCallbackContext :: Ptr ()
   }
-  deriving (Show, Eq, Generic)
-  deriving anyclass (GStorable)
+  deriving (Show, Eq)
+
+instance Storable DPIPoolCreateParams where
+    sizeOf _ = (9 * sizeOf (undefined :: CUInt))
+              + (4 * sizeOf (undefined :: CInt))
+              + sizeOf (undefined :: DPIPoolGetMode)
+              + sizeOf (undefined :: FunPtr ())
+              + sizeOf (undefined :: Ptr ())
+              + (2 * sizeOf (undefined :: CString))
+
+    alignment _ = alignment (undefined :: CUInt)
+
+    peek ptr = do
+      let base = castPtr ptr
+      DPIPoolCreateParams
+        <$> peek base                           -- dpi_minSessions
+        <*> peek (base `plusPtr`     sizeOf (undefined :: CUInt)) -- dpi_maxSessions
+        <*> peek (base `plusPtr` (2 * sizeOf (undefined :: CUInt))) -- dpi_sessionIncrement
+        <*> peek (base `plusPtr`( 3 * sizeOf (undefined :: CUInt))) -- dpi_pingInterval
+        <*> peek (base `plusPtr` (3 * sizeOf (undefined :: CUInt))
+                       `plusPtr`     sizeOf (undefined :: CInt)) -- dpi_pingTimeout
+        <*> peek (base `plusPtr` (3 * sizeOf (undefined :: CUInt))
+                       `plusPtr` (2 * sizeOf (undefined :: CInt))) -- dpi_homogeneous
+        <*> peek (base `plusPtr` (3 * sizeOf (undefined :: CUInt))
+                       `plusPtr` (3 * sizeOf (undefined :: CInt))) -- dpi_externalAuth
+        <*> peek (base `plusPtr` (3 * sizeOf (undefined :: CUInt))
+                       `plusPtr` (4 * sizeOf (undefined :: CInt))) -- dpi_getMode
+        <*> peek (base `plusPtr` (3 * sizeOf (undefined :: CUInt))
+                       `plusPtr` (4 * sizeOf (undefined :: CInt))
+                       `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)) -- dpi_outPoolName
+        <*> peek (base `plusPtr` (3 * sizeOf (undefined :: CUInt))
+                       `plusPtr` (4 * sizeOf (undefined :: CInt))
+                       `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                       `plusPtr`     sizeOf (undefined :: CString)) -- dpi_outPoolNameLength
+        <*> peek (base `plusPtr` (4 * sizeOf (undefined :: CUInt))
+                       `plusPtr` (4 * sizeOf (undefined :: CInt))
+                       `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                       `plusPtr`     sizeOf (undefined :: CString)) -- dpi_timeout
+        <*> peek (base `plusPtr` (5 * sizeOf (undefined :: CUInt))
+                       `plusPtr` (4 * sizeOf (undefined :: CInt))
+                       `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                       `plusPtr`     sizeOf (undefined :: CString)) -- dpi_waitTimeout
+        <*> peek (base `plusPtr` (6 * sizeOf (undefined :: CUInt))
+                       `plusPtr` (4 * sizeOf (undefined :: CInt))
+                       `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                       `plusPtr`     sizeOf (undefined :: CString)) -- dpi_maxLifetimeSession
+        <*> peek (base `plusPtr` (7 * sizeOf (undefined :: CUInt))
+                       `plusPtr` (4 * sizeOf (undefined :: CInt))
+                       `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                       `plusPtr`     sizeOf (undefined :: CString)) -- dpi_plsqlFixupCallback
+        <*> peek (base `plusPtr` (7 * sizeOf (undefined :: CUInt))
+                       `plusPtr` (4 * sizeOf (undefined :: CInt))
+                       `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                       `plusPtr` (2 * sizeOf (undefined :: CString))) -- dpi_plsqlFixupCallbackLength
+        <*> peek (base `plusPtr` (8 * sizeOf (undefined :: CUInt))
+                       `plusPtr` (4 * sizeOf (undefined :: CInt))
+                       `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                       `plusPtr` (2 * sizeOf (undefined :: CString))) -- dpi_maxSessionsPerShard
+        <*> peek (base `plusPtr` (9 * sizeOf (undefined :: CUInt))
+                       `plusPtr` (4 * sizeOf (undefined :: CInt))
+                       `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                       `plusPtr` (2 * sizeOf (undefined :: CString))) -- dpi_accessTokenCallback
+        <*> peek (base `plusPtr` (10 * sizeOf (undefined :: CUInt))
+                       `plusPtr` (4 * sizeOf (undefined :: CInt))
+                       `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                       `plusPtr` (2 * sizeOf (undefined :: CString))) -- dpi_accessTokenCallbackContext
+
+    poke ptr DPIPoolCreateParams{..} = do
+      let base = castPtr ptr
+      poke base dpi_minSessions
+      poke (base `plusPtr`     sizeOf (undefined :: CUInt)) dpi_maxSessions
+      poke (base `plusPtr` (2 * sizeOf (undefined :: CUInt))) dpi_sessionIncrement
+      poke (base `plusPtr`( 3 * sizeOf (undefined :: CUInt))) dpi_pingInterval
+      poke (base `plusPtr` (3 * sizeOf (undefined :: CUInt))
+                 `plusPtr`     sizeOf (undefined :: CInt)) dpi_pingTimeout
+      poke (base `plusPtr` (3 * sizeOf (undefined :: CUInt))
+                 `plusPtr` (2 * sizeOf (undefined :: CInt))) dpi_homogeneous
+      poke (base `plusPtr` (3 * sizeOf (undefined :: CUInt))
+                 `plusPtr` (3 * sizeOf (undefined :: CInt))) dpi_externalAuth
+      poke (base `plusPtr` (3 * sizeOf (undefined :: CUInt))
+                 `plusPtr` (4 * sizeOf (undefined :: CInt))) dpi_getMode
+      poke (base `plusPtr` (3 * sizeOf (undefined :: CUInt))
+                 `plusPtr` (4 * sizeOf (undefined :: CInt))
+                 `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)) dpi_outPoolName
+      poke (base `plusPtr` (3 * sizeOf (undefined :: CUInt))
+                 `plusPtr` (4 * sizeOf (undefined :: CInt))
+                 `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                 `plusPtr`     sizeOf (undefined :: CString)) dpi_outPoolNameLength
+      poke (base `plusPtr` (4 * sizeOf (undefined :: CUInt))
+                 `plusPtr` (4 * sizeOf (undefined :: CInt))
+                 `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                 `plusPtr`     sizeOf (undefined :: CString)) dpi_timeout
+      poke (base `plusPtr` (5 * sizeOf (undefined :: CUInt))
+                 `plusPtr` (4 * sizeOf (undefined :: CInt))
+                 `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                 `plusPtr`     sizeOf (undefined :: CString)) dpi_waitTimeout
+      poke (base `plusPtr` (6 * sizeOf (undefined :: CUInt))
+                 `plusPtr` (4 * sizeOf (undefined :: CInt))
+                 `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                 `plusPtr`     sizeOf (undefined :: CString)) dpi_maxLifetimeSession
+      poke (base `plusPtr` (7 * sizeOf (undefined :: CUInt))
+                 `plusPtr` (4 * sizeOf (undefined :: CInt))
+                 `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                 `plusPtr`     sizeOf (undefined :: CString)) dpi_plsqlFixupCallback
+      poke (base `plusPtr` (7 * sizeOf (undefined :: CUInt))
+                 `plusPtr` (4 * sizeOf (undefined :: CInt))
+                 `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                 `plusPtr` (2 * sizeOf (undefined :: CString))) dpi_plsqlFixupCallbackLength
+      poke (base `plusPtr` (8 * sizeOf (undefined :: CUInt))
+                 `plusPtr` (4 * sizeOf (undefined :: CInt))
+                 `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                 `plusPtr` (2 * sizeOf (undefined :: CString))) dpi_maxSessionsPerShard
+      poke (base `plusPtr` (9 * sizeOf (undefined :: CUInt))
+                 `plusPtr` (4 * sizeOf (undefined :: CInt))
+                 `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                 `plusPtr` (2 * sizeOf (undefined :: CString))) dpi_accessTokenCallback
+      poke (base `plusPtr` (10 * sizeOf (undefined :: CUInt))
+                 `plusPtr` (4 * sizeOf (undefined :: CInt))
+                 `plusPtr`     sizeOf (undefined :: DPIPoolGetMode)
+                 `plusPtr` (2 * sizeOf (undefined :: CString))) dpi_accessTokenCallbackContext
 
 data DPIPoolGetMode
   = DPI_MODE_POOL_GET_FORCEGET
@@ -384,8 +512,302 @@ data ConnectionCreateParams = ConnectionCreateParams
   , numSuperShardingKeyColumns :: Word8
   , outNewSession :: CInt
   }
-  deriving (Show, Eq, Generic)
-  deriving anyclass (GStorable)
+  deriving (Show, Eq)
+
+instance Storable ConnectionCreateParams where
+
+    sizeOf _ =  sizeOf (undefined :: DPIAuthMode)
+              + (4 * sizeOf (undefined :: CString))
+              + (5 * sizeOf (undefined :: CUInt))
+              + sizeOf (undefined :: DPIPurity)
+              + sizeOf (undefined :: DPIAppContext)
+              + (4 * sizeOf (undefined :: CInt))
+              + sizeOf (undefined :: Ptr ())
+              + sizeOf (undefined :: DPIPool)
+              + (2 * sizeOf (undefined :: DPIShardingKeyColumn))
+              + (2 * sizeOf (undefined :: Word8))
+    alignment _ = alignment (undefined :: CUInt)
+    
+    peek ptr = do
+      let base = castPtr ptr
+      ConnectionCreateParams
+        <$> peek (base `plusPtr` 0)                                 -- authMode
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode)) -- connectionClass
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` sizeOf (undefined :: CString))     -- connectionClassLength
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` sizeOf (undefined :: CString)
+                       `plusPtr` sizeOf (undefined :: CUInt))     -- purity
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` sizeOf (undefined :: CString)
+                       `plusPtr` sizeOf (undefined :: CUInt)
+                       `plusPtr` sizeOf (undefined :: DPIPurity)) -- newPassword
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` (2 * sizeOf (undefined :: CString))
+                       `plusPtr` sizeOf (undefined :: CUInt)
+                       `plusPtr` sizeOf (undefined :: DPIPurity)) -- newPasswordLength
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` (2 * sizeOf (undefined :: CString))
+                       `plusPtr` (2 * sizeOf (undefined :: CUInt))
+                       `plusPtr` sizeOf (undefined :: DPIPurity)) -- appContenxt
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` (2 * sizeOf (undefined :: CString))
+                       `plusPtr` (2 * sizeOf (undefined :: CUInt))
+                       `plusPtr` sizeOf (undefined :: DPIPurity)
+                       `plusPtr` sizeOf (undefined :: DPIAppContext)) -- numAppContext
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` (2 * sizeOf (undefined :: CString))
+                       `plusPtr` (3 * sizeOf (undefined :: CUInt))
+                       `plusPtr` sizeOf (undefined :: DPIPurity)
+                       `plusPtr` sizeOf (undefined :: DPIAppContext)) -- externalAuth
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` (2 * sizeOf (undefined :: CString))
+                       `plusPtr` (3 * sizeOf (undefined :: CUInt))
+                       `plusPtr` sizeOf (undefined :: DPIPurity)
+                       `plusPtr` sizeOf (undefined :: CInt)
+                       `plusPtr` sizeOf (undefined :: DPIAppContext)) -- externalHandle
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` (2 * sizeOf (undefined :: CString))
+                       `plusPtr` (3 * sizeOf (undefined :: CUInt))
+                       `plusPtr` sizeOf (undefined :: DPIPurity)
+                       `plusPtr` sizeOf (undefined :: CInt)
+                       `plusPtr` sizeOf (undefined :: DPIAppContext)
+                       `plusPtr` sizeOf (undefined :: Ptr ())) -- pool
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` (2 * sizeOf (undefined :: CString))
+                       `plusPtr` (3 * sizeOf (undefined :: CUInt))
+                       `plusPtr` sizeOf (undefined :: DPIPurity)
+                       `plusPtr` sizeOf (undefined :: CInt)
+                       `plusPtr` sizeOf (undefined :: DPIAppContext)
+                       `plusPtr` sizeOf (undefined :: Ptr ())
+                       `plusPtr` sizeOf (undefined :: DPIPool)) -- tag
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` (3 * sizeOf (undefined :: CString))
+                       `plusPtr` (3 * sizeOf (undefined :: CUInt))
+                       `plusPtr` sizeOf (undefined :: DPIPurity)
+                       `plusPtr` sizeOf (undefined :: CInt)
+                       `plusPtr` sizeOf (undefined :: DPIAppContext)
+                       `plusPtr` sizeOf (undefined :: Ptr ())
+                       `plusPtr` sizeOf (undefined :: DPIPool)) -- tagLength
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` (3 * sizeOf (undefined :: CString))
+                       `plusPtr` (4 * sizeOf (undefined :: CUInt))
+                       `plusPtr` sizeOf (undefined :: DPIPurity)
+                       `plusPtr` sizeOf (undefined :: CInt)
+                       `plusPtr` sizeOf (undefined :: DPIAppContext)
+                       `plusPtr` sizeOf (undefined :: Ptr ())
+                       `plusPtr` sizeOf (undefined :: DPIPool)) -- matchAnyTag
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` (3 * sizeOf (undefined :: CString))
+                       `plusPtr` (4 * sizeOf (undefined :: CUInt))
+                       `plusPtr` sizeOf (undefined :: DPIPurity)
+                       `plusPtr` (2 * sizeOf (undefined :: CInt))
+                       `plusPtr` sizeOf (undefined :: DPIAppContext)
+                       `plusPtr` sizeOf (undefined :: Ptr ())
+                       `plusPtr` sizeOf (undefined :: DPIPool)) -- outTag
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` (4 * sizeOf (undefined :: CString))
+                       `plusPtr` (4 * sizeOf (undefined :: CUInt))
+                       `plusPtr` sizeOf (undefined :: DPIPurity)
+                       `plusPtr` (2 * sizeOf (undefined :: CInt))
+                       `plusPtr` sizeOf (undefined :: DPIAppContext)
+                       `plusPtr` sizeOf (undefined :: Ptr ())
+                       `plusPtr` sizeOf (undefined :: DPIPool)) -- outTagLength
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` (4 * sizeOf (undefined :: CString))
+                       `plusPtr` (5 * sizeOf (undefined :: CUInt))
+                       `plusPtr` sizeOf (undefined :: DPIPurity)
+                       `plusPtr` (2 * sizeOf (undefined :: CInt))
+                       `plusPtr` sizeOf (undefined :: DPIAppContext)
+                       `plusPtr` sizeOf (undefined :: Ptr ())
+                       `plusPtr` sizeOf (undefined :: DPIPool)) -- outTagFound
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` (4 * sizeOf (undefined :: CString))
+                       `plusPtr` (5 * sizeOf (undefined :: CUInt))
+                       `plusPtr` sizeOf (undefined :: DPIPurity)
+                       `plusPtr` (3 * sizeOf (undefined :: CInt))
+                       `plusPtr` sizeOf (undefined :: DPIAppContext)
+                       `plusPtr` sizeOf (undefined :: Ptr ())
+                       `plusPtr` sizeOf (undefined :: DPIPool)) -- shardingKeyColumn
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` (4 * sizeOf (undefined :: CString))
+                       `plusPtr` (5 * sizeOf (undefined :: CUInt))
+                       `plusPtr` sizeOf (undefined :: DPIPurity)
+                       `plusPtr` (3 * sizeOf (undefined :: CInt))
+                       `plusPtr` sizeOf (undefined :: DPIAppContext)
+                       `plusPtr` sizeOf (undefined :: Ptr ())
+                       `plusPtr` sizeOf (undefined :: DPIPool)
+                       `plusPtr` sizeOf (undefined :: DPIShardingKeyColumn)) -- numShardingKeyColumns
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` (4 * sizeOf (undefined :: CString))
+                       `plusPtr` (5 * sizeOf (undefined :: CUInt))
+                       `plusPtr` sizeOf (undefined :: DPIPurity)
+                       `plusPtr` (3 * sizeOf (undefined :: CInt))
+                       `plusPtr` sizeOf (undefined :: DPIAppContext)
+                       `plusPtr` sizeOf (undefined :: Ptr ())
+                       `plusPtr` sizeOf (undefined :: DPIPool)
+                       `plusPtr` sizeOf (undefined :: DPIShardingKeyColumn)
+                       `plusPtr` sizeOf (undefined :: Word8)) -- superShardingKeyColumns
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` (4 * sizeOf (undefined :: CString))
+                       `plusPtr` (5 * sizeOf (undefined :: CUInt))
+                       `plusPtr` sizeOf (undefined :: DPIPurity)
+                       `plusPtr` (3 * sizeOf (undefined :: CInt))
+                       `plusPtr` sizeOf (undefined :: DPIAppContext)
+                       `plusPtr` sizeOf (undefined :: Ptr ())
+                       `plusPtr` sizeOf (undefined :: DPIPool)
+                       `plusPtr` (2 * sizeOf (undefined :: DPIShardingKeyColumn))
+                       `plusPtr` sizeOf (undefined :: Word8)) -- numSuperShardingKeyColumns
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+                       `plusPtr` (4 * sizeOf (undefined :: CString))
+                       `plusPtr` (5 * sizeOf (undefined :: CUInt))
+                       `plusPtr` sizeOf (undefined :: DPIPurity)
+                       `plusPtr` (3 * sizeOf (undefined :: CInt))
+                       `plusPtr` sizeOf (undefined :: DPIAppContext)
+                       `plusPtr` sizeOf (undefined :: Ptr ())
+                       `plusPtr` sizeOf (undefined :: DPIPool)
+                       `plusPtr` (2 * sizeOf (undefined :: DPIShardingKeyColumn))
+                       `plusPtr` (2 * sizeOf (undefined :: Word8))) -- outNewSession
+
+    poke ptr ConnectionCreateParams{..} = do
+      let base = castPtr ptr
+      poke (base `plusPtr` 0) authMode
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode)) connectionClass
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` sizeOf (undefined :: CString)) connectionClassLength
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` sizeOf (undefined :: CString)
+              `plusPtr` sizeOf (undefined :: CUInt))  purity
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` sizeOf (undefined :: CString)
+              `plusPtr` sizeOf (undefined :: CUInt)
+              `plusPtr` sizeOf (undefined :: DPIPurity)) newPassword
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` (2 * sizeOf (undefined :: CString))
+              `plusPtr` sizeOf (undefined :: CUInt)
+              `plusPtr` sizeOf (undefined :: DPIPurity)) newPasswordLength
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` (2 * sizeOf (undefined :: CString))
+              `plusPtr` (2 * sizeOf (undefined :: CUInt))
+              `plusPtr` sizeOf (undefined :: DPIPurity)) appContenxt
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` (2 * sizeOf (undefined :: CString))
+              `plusPtr` (2 * sizeOf (undefined :: CUInt))
+              `plusPtr` sizeOf (undefined :: DPIPurity)
+              `plusPtr` sizeOf (undefined :: DPIAppContext)) numAppContext
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` (2 * sizeOf (undefined :: CString))
+              `plusPtr` (3 * sizeOf (undefined :: CUInt))
+              `plusPtr` sizeOf (undefined :: DPIPurity)
+              `plusPtr` sizeOf (undefined :: DPIAppContext)) externalAuth
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` (2 * sizeOf (undefined :: CString))
+              `plusPtr` (3 * sizeOf (undefined :: CUInt))
+              `plusPtr` sizeOf (undefined :: DPIPurity)
+              `plusPtr` sizeOf (undefined :: CInt)
+              `plusPtr` sizeOf (undefined :: DPIAppContext)) externalHandle
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` (2 * sizeOf (undefined :: CString))
+              `plusPtr` (3 * sizeOf (undefined :: CUInt))
+              `plusPtr` sizeOf (undefined :: DPIPurity)
+              `plusPtr` sizeOf (undefined :: CInt)
+              `plusPtr` sizeOf (undefined :: DPIAppContext)
+              `plusPtr` sizeOf (undefined :: Ptr ())) pool
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` (2 * sizeOf (undefined :: CString))
+              `plusPtr` (3 * sizeOf (undefined :: CUInt))
+              `plusPtr` sizeOf (undefined :: DPIPurity)
+              `plusPtr` sizeOf (undefined :: CInt)
+              `plusPtr` sizeOf (undefined :: DPIAppContext)
+              `plusPtr` sizeOf (undefined :: Ptr ())
+              `plusPtr` sizeOf (undefined :: DPIPool)) tag
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` (3 * sizeOf (undefined :: CString))
+              `plusPtr` (3 * sizeOf (undefined :: CUInt))
+              `plusPtr` sizeOf (undefined :: DPIPurity)
+              `plusPtr` sizeOf (undefined :: CInt)
+              `plusPtr` sizeOf (undefined :: DPIAppContext)
+              `plusPtr` sizeOf (undefined :: Ptr ())
+              `plusPtr` sizeOf (undefined :: DPIPool)) tagLength
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` (3 * sizeOf (undefined :: CString))
+              `plusPtr` (4 * sizeOf (undefined :: CUInt))
+              `plusPtr` sizeOf (undefined :: DPIPurity)
+              `plusPtr` sizeOf (undefined :: CInt)
+              `plusPtr` sizeOf (undefined :: DPIAppContext)
+              `plusPtr` sizeOf (undefined :: Ptr ())
+              `plusPtr` sizeOf (undefined :: DPIPool)) matchAnyTag
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` (3 * sizeOf (undefined :: CString))
+              `plusPtr` (4 * sizeOf (undefined :: CUInt))
+              `plusPtr` sizeOf (undefined :: DPIPurity)
+              `plusPtr` (2 * sizeOf (undefined :: CInt))
+              `plusPtr` sizeOf (undefined :: DPIAppContext)
+              `plusPtr` sizeOf (undefined :: Ptr ())
+              `plusPtr` sizeOf (undefined :: DPIPool)) outTag
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` (4 * sizeOf (undefined :: CString))
+              `plusPtr` (4 * sizeOf (undefined :: CUInt))
+              `plusPtr` sizeOf (undefined :: DPIPurity)
+              `plusPtr` (2 * sizeOf (undefined :: CInt))
+              `plusPtr` sizeOf (undefined :: DPIAppContext)
+              `plusPtr` sizeOf (undefined :: Ptr ())
+              `plusPtr` sizeOf (undefined :: DPIPool)) outTagLength
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` (4 * sizeOf (undefined :: CString))
+              `plusPtr` (5 * sizeOf (undefined :: CUInt))
+              `plusPtr` sizeOf (undefined :: DPIPurity)
+              `plusPtr` (2 * sizeOf (undefined :: CInt))
+              `plusPtr` sizeOf (undefined :: DPIAppContext)
+              `plusPtr` sizeOf (undefined :: Ptr ())
+              `plusPtr` sizeOf (undefined :: DPIPool)) outTagFound
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` (4 * sizeOf (undefined :: CString))
+              `plusPtr` (5 * sizeOf (undefined :: CUInt))
+              `plusPtr` sizeOf (undefined :: DPIPurity)
+              `plusPtr` (3 * sizeOf (undefined :: CInt))
+              `plusPtr` sizeOf (undefined :: DPIAppContext)
+              `plusPtr` sizeOf (undefined :: Ptr ())
+              `plusPtr` sizeOf (undefined :: DPIPool)) shardingKeyColumn
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` (4 * sizeOf (undefined :: CString))
+              `plusPtr` (5 * sizeOf (undefined :: CUInt))
+              `plusPtr` sizeOf (undefined :: DPIPurity)
+              `plusPtr` (3 * sizeOf (undefined :: CInt))
+              `plusPtr` sizeOf (undefined :: DPIAppContext)
+              `plusPtr` sizeOf (undefined :: Ptr ())
+              `plusPtr` sizeOf (undefined :: DPIPool)
+              `plusPtr` sizeOf (undefined :: DPIShardingKeyColumn)) numShardingKeyColumns
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` (4 * sizeOf (undefined :: CString))
+              `plusPtr` (5 * sizeOf (undefined :: CUInt))
+              `plusPtr` sizeOf (undefined :: DPIPurity)
+              `plusPtr` (3 * sizeOf (undefined :: CInt))
+              `plusPtr` sizeOf (undefined :: DPIAppContext)
+              `plusPtr` sizeOf (undefined :: Ptr ())
+              `plusPtr` sizeOf (undefined :: DPIPool)
+              `plusPtr` sizeOf (undefined :: DPIShardingKeyColumn)
+              `plusPtr` sizeOf (undefined :: Word8)) superShardingKeyColumns
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` (4 * sizeOf (undefined :: CString))
+              `plusPtr` (5 * sizeOf (undefined :: CUInt))
+              `plusPtr` sizeOf (undefined :: DPIPurity)
+              `plusPtr` (3 * sizeOf (undefined :: CInt))
+              `plusPtr` sizeOf (undefined :: DPIAppContext)
+              `plusPtr` sizeOf (undefined :: Ptr ())
+              `plusPtr` sizeOf (undefined :: DPIPool)
+              `plusPtr` (2 * sizeOf (undefined :: DPIShardingKeyColumn))
+              `plusPtr` sizeOf (undefined :: Word8)) numSuperShardingKeyColumns
+      poke (base `plusPtr` sizeOf (undefined :: DPIAuthMode) 
+              `plusPtr` (4 * sizeOf (undefined :: CString))
+              `plusPtr` (5 * sizeOf (undefined :: CUInt))
+              `plusPtr` sizeOf (undefined :: DPIPurity)
+              `plusPtr` (3 * sizeOf (undefined :: CInt))
+              `plusPtr` sizeOf (undefined :: DPIAppContext)
+              `plusPtr` sizeOf (undefined :: Ptr ())
+              `plusPtr` sizeOf (undefined :: DPIPool)
+              `plusPtr` (2 * sizeOf (undefined :: DPIShardingKeyColumn))
+              `plusPtr` (2 * sizeOf (undefined :: Word8))) outNewSession
 
 data DPICommonCreateParams = DPICommonCreateParams
   { createMode :: DPICreateMode
@@ -398,8 +820,64 @@ data DPICommonCreateParams = DPICommonCreateParams
   , sodaMetadataCache :: Int
   , stmtCacheSize :: CInt
   }
-  deriving (Show, Eq, Generic)
-  deriving anyclass (GStorable)
+  deriving (Show, Eq)
+
+instance Storable DPICommonCreateParams where
+    sizeOf _ =  sizeOf (undefined :: DPICreateMode)
+              + (4 * sizeOf (undefined :: CString))
+              + (3 * sizeOf (undefined :: CInt))
+              + sizeOf (undefined :: Int)
+
+    alignment _ = alignment (undefined :: Int)
+
+    peek ptr = do
+      let base = castPtr ptr
+      DPICommonCreateParams
+        <$> peek (base `plusPtr` 0)                                   -- createMode
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPICreateMode)) -- encoding
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPICreateMode) 
+                       `plusPtr` sizeOf (undefined :: CString))       -- nencoding
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPICreateMode) 
+                       `plusPtr` (2 * sizeOf (undefined :: CString))) -- edition
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPICreateMode) 
+                       `plusPtr` (3 * sizeOf (undefined :: CString))) -- editionLength
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPICreateMode) 
+                       `plusPtr` (3 * sizeOf (undefined :: CString))
+                       `plusPtr` sizeOf (undefined :: CInt)) -- driverName
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPICreateMode) 
+                       `plusPtr` (4 * sizeOf (undefined :: CString))
+                       `plusPtr` sizeOf (undefined :: CInt)) -- driverNameLength
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPICreateMode) 
+                       `plusPtr` (4 * sizeOf (undefined :: CString))
+                       `plusPtr` (2 * sizeOf (undefined :: CInt))) -- sodaMetadataCache
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPICreateMode) 
+                       `plusPtr` (4 * sizeOf (undefined :: CString))
+                       `plusPtr` (2 * sizeOf (undefined :: CInt))
+                       `plusPtr` sizeOf (undefined :: Int)) -- stmtCacheSize
+
+    poke ptr DPICommonCreateParams{..} = do
+        let base = castPtr ptr
+        poke (base `plusPtr` 0) createMode
+        poke (base `plusPtr` sizeOf (undefined :: DPICreateMode)) encoding
+        poke (base `plusPtr` sizeOf (undefined :: DPICreateMode) 
+                       `plusPtr` sizeOf (undefined :: CString)) nencoding
+        poke (base `plusPtr` sizeOf (undefined :: DPICreateMode) 
+                       `plusPtr` (2 * sizeOf (undefined :: CString))) edition
+        poke (base `plusPtr` sizeOf (undefined :: DPICreateMode) 
+                       `plusPtr` (3 * sizeOf (undefined :: CString))) editionLength
+        poke (base `plusPtr` sizeOf (undefined :: DPICreateMode) 
+                       `plusPtr` (3 * sizeOf (undefined :: CString))
+                       `plusPtr` sizeOf (undefined :: CInt)) driverName
+        poke (base `plusPtr` sizeOf (undefined :: DPICreateMode) 
+                       `plusPtr` (4 * sizeOf (undefined :: CString))
+                       `plusPtr` sizeOf (undefined :: CInt)) driverNameLength
+        poke (base `plusPtr` sizeOf (undefined :: DPICreateMode) 
+                       `plusPtr` (4 * sizeOf (undefined :: CString))
+                       `plusPtr` (2 * sizeOf (undefined :: CInt))) sodaMetadataCache
+        poke (base `plusPtr` sizeOf (undefined :: DPICreateMode) 
+                       `plusPtr` (4 * sizeOf (undefined :: CString))
+                       `plusPtr` (2 * sizeOf (undefined :: CInt))
+                       `plusPtr` sizeOf (undefined :: Int)) stmtCacheSize
 
 -- | typedef uint32_t dpiCreateMode;
 data DPICreateMode
@@ -664,8 +1142,61 @@ data DPITimestamp = DPITimestamp
   , tzHourOffset :: Int8
   , tzMinuteOffset :: Int8
   }
-  deriving (Show, Eq, Generic)
-  deriving anyclass (GStorable)
+  deriving (Show, Eq)
+
+instance Storable DPITimestamp where
+    sizeOf _ = sizeOf (undefined :: Int16)
+             + (5 * sizeOf (undefined :: Word8))
+             + sizeOf (undefined :: CUInt)
+             + (2 * sizeOf (undefined :: Int8))
+
+    alignment _ = sizeOf (undefined :: CUInt)
+
+    peek ptr = do
+        let base = castPtr ptr
+        DPITimestamp
+          <$> peek (base `plusPtr` 0)                           -- year
+          <*> peek (base `plusPtr`      sizeOf (undefined :: Int16)) -- month
+          <*> peek (base `plusPtr` sizeOf (undefined :: Int16)
+                        `plusPtr` sizeOf (undefined :: Word8)) -- day
+          <*> peek (base `plusPtr` sizeOf (undefined :: Int16)
+                        `plusPtr` (2 * sizeOf (undefined :: Word8))) -- hour
+          <*> peek (base `plusPtr` sizeOf (undefined :: Int16)
+                        `plusPtr` (3 * sizeOf (undefined :: Word8))) -- minute
+          <*> peek (base `plusPtr` sizeOf (undefined :: Int16)
+                        `plusPtr` (4 * sizeOf (undefined :: Word8))) -- second
+          <*> peek (base `plusPtr` sizeOf (undefined :: Int16)
+                        `plusPtr` (5 * sizeOf (undefined :: Word8))) -- fsecond
+          <*> peek (base `plusPtr` sizeOf (undefined :: Int16)
+                        `plusPtr` (5 * sizeOf (undefined :: Word8))
+                        `plusPtr` sizeOf (undefined :: CUInt)) -- tzHourOffset
+          <*> peek (base `plusPtr` sizeOf (undefined :: Int16)
+                        `plusPtr` (5 * sizeOf (undefined :: Word8))
+                        `plusPtr` sizeOf (undefined :: CUInt)
+                        `plusPtr` sizeOf (undefined :: Int8)) -- tzMinuteOffset
+    
+    poke ptr DPITimestamp{..} = do
+        let base = castPtr ptr
+        poke (base `plusPtr` 0) year
+        poke (base `plusPtr` sizeOf (undefined :: Int16)) month
+        poke (base `plusPtr` sizeOf (undefined :: Int16) 
+                       `plusPtr` sizeOf (undefined :: Word8)) day
+        poke (base `plusPtr` sizeOf (undefined :: Int16) 
+                       `plusPtr` (2 * sizeOf (undefined :: Word8))) hour
+        poke (base `plusPtr` sizeOf (undefined :: Int16) 
+                       `plusPtr` (3 * sizeOf (undefined :: Word8))) minute
+        poke (base `plusPtr` sizeOf (undefined :: Int16) 
+                       `plusPtr` (4 * sizeOf (undefined :: Word8))) second
+        poke (base `plusPtr` sizeOf (undefined :: Int16) 
+                       `plusPtr` (5 * sizeOf (undefined :: Word8))) fsecond
+        poke (base `plusPtr` sizeOf (undefined :: Int16) 
+                       `plusPtr` (5 * sizeOf (undefined :: Word8))
+                       `plusPtr` sizeOf (undefined :: CUInt)) tzHourOffset
+        poke (base `plusPtr` sizeOf (undefined :: Int16) 
+                       `plusPtr` (5 * sizeOf (undefined :: Word8))
+                       `plusPtr` sizeOf (undefined :: CUInt)
+                       `plusPtr` sizeOf (undefined :: Int8)) tzMinuteOffset
+
 
 {- | Converts a DPITimestamp into the UTCTime zone by applying the offsets
 to the year, month, day, hour, minutes and seconds
@@ -701,8 +1232,40 @@ data DPIAppContext = DPIAppContext
   , value :: CString
   , valueLength :: CUInt
   }
-  deriving (Show, Eq, Generic)
-  deriving anyclass (GStorable)
+  deriving (Show, Eq)
+
+instance Storable DPIAppContext where
+    sizeOf _ = (3 * sizeOf (undefined :: CString))
+                + (3 * sizeOf (undefined :: CUInt))
+
+    alignment _ = alignment (undefined :: CUInt)
+
+    peek ptr = do
+        let base = castPtr ptr
+        DPIAppContext
+          <$> peek (base `plusPtr` 0)                           -- namespaceName
+          <*> peek (base `plusPtr`  sizeOf (undefined :: CString)) -- namespaceNameLength
+          <*> peek (base `plusPtr`  sizeOf (undefined :: CString)
+                            `plusPtr`  sizeOf (undefined :: CUInt)) -- name
+          <*> peek (base `plusPtr` (2 * sizeOf (undefined :: CString))
+                            `plusPtr` sizeOf (undefined :: CUInt)) -- nameLength
+          <*> peek (base `plusPtr` (2 * sizeOf (undefined :: CString))
+                            `plusPtr` (2 * sizeOf (undefined :: CUInt))) -- value
+          <*> peek (base `plusPtr` (3 * sizeOf (undefined :: CString))
+                            `plusPtr` (2 * sizeOf (undefined :: CUInt))) -- valueLength
+
+    poke ptr DPIAppContext{..} = do
+        let base = castPtr ptr
+        poke (base `plusPtr` 0) namespaceName
+        poke (base `plusPtr` sizeOf (undefined :: CString)) namespaceNameLength
+        poke (base `plusPtr` sizeOf (undefined :: CString)
+                        `plusPtr` sizeOf (undefined :: CUInt)) name
+        poke (base `plusPtr` (2 * sizeOf (undefined :: CString))
+                        `plusPtr` sizeOf (undefined :: CUInt)) nameLength
+        poke (base `plusPtr` (2 * sizeOf (undefined :: CString))
+                        `plusPtr` (2 * sizeOf (undefined :: CUInt))) value
+        poke (base `plusPtr` (3 * sizeOf (undefined :: CString))
+                        `plusPtr` (2 * sizeOf (undefined :: CUInt))) valueLength
 
 data DPIContextCreateParams = DPIContextCreateParams
   { defaultDriverName :: CString
@@ -711,8 +1274,29 @@ data DPIContextCreateParams = DPIContextCreateParams
   , oracleClientLibDir :: CString
   , oracleClientConfigDir :: CString
   }
-  deriving (Show, Eq, Generic)
-  deriving anyclass (GStorable)
+  deriving (Show, Eq)
+
+instance Storable DPIContextCreateParams where
+    sizeOf _ = 5 * sizeOf (undefined :: CString)
+    alignment _ = alignment (undefined :: CString)
+
+    peek ptr = do
+        let base = castPtr ptr
+        DPIContextCreateParams
+            <$> peek (base `plusPtr` 0) -- defaultDriverName
+            <*> peek (base `plusPtr` sizeOf (undefined :: CString)) -- defaultEncoding
+            <*> peek (base `plusPtr` (2 * sizeOf (undefined :: CString))) -- loadErrorUrl
+            <*> peek (base `plusPtr` (3 * sizeOf (undefined :: CString))) -- oracleClientLibDir
+            <*> peek (base `plusPtr` (4 * sizeOf (undefined :: CString))) -- oracleClientConfigDir
+
+    poke ptr DPIContextCreateParams{..} = do
+        let base = castPtr ptr
+        poke (base `plusPtr` 0) defaultDriverName
+        poke (base `plusPtr` sizeOf (undefined :: CString)) defaultEncoding
+        poke (base `plusPtr` (2 * sizeOf (undefined :: CString))) loadErrorUrl
+        poke (base `plusPtr` (3 * sizeOf (undefined :: CString))) oracleClientLibDir
+        poke (base `plusPtr` (4 * sizeOf (undefined :: CString))) oracleClientConfigDir
+        
 
 foreign import ccall "dpiContext_getError"
   dpiContext_getError :: DPIContext -> Ptr ErrorInfo -> IO ()
@@ -937,6 +1521,7 @@ data DPIOracleType
   | DPI_ORACLE_TYPE_UROWID
   | DPI_ORACLE_TYPE_LONG_NVARCHAR
   | DPI_ORACLE_TYPE_MAX
+    deriving (Eq, Show)
 
 instance Storable DPIOracleType where
   sizeOf _ = sizeOf (undefined :: CUInt)
diff --git a/src/Database/Oracle/Simple/JSON.hs b/src/Database/Oracle/Simple/JSON.hs
index 28fa8fb..c45adc9 100644
--- a/src/Database/Oracle/Simple/JSON.hs
+++ b/src/Database/Oracle/Simple/JSON.hs
@@ -8,7 +8,7 @@
 {-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE UndecidableInstances #-}
 
-module Database.Oracle.Simple.JSON (AesonField (..), JsonDecodeError (..)) where
+module Database.Oracle.Simple.JSON (AesonField (..), JsonDecodeError (..), DPIJsonNode(..)) where
 
 import Control.Exception (Exception (displayException), SomeException, catch, evaluate, throwIO)
 import Control.Monad (void, (<=<))
@@ -22,9 +22,10 @@ import Data.Scientific (fromFloatDigits)
 import Data.String (fromString)
 import Data.Text.Encoding (decodeUtf8)
 import qualified Data.Vector as Vector
-import Foreign (Ptr, Storable, alloca, peek, peekArray)
+import Foreign (Ptr, Storable, alloca, peekArray)
 import Foreign.C (CDouble (CDouble), CInt (CInt), CString, CUInt (CUInt), peekCStringLen)
-import Foreign.Storable.Generic (GStorable)
+import Foreign.Storable.Generic (GStorable, Storable(..))
+import Foreign.Ptr (castPtr, plusPtr)
 import GHC.Generics (Generic)
 
 import Database.Oracle.Simple.FromField (FieldParser (FieldParser), FromField (fromDPINativeType, fromField), ReadDPIBuffer)
@@ -137,9 +138,27 @@ data DPIJsonNode = DPIJsonNode
   { djnOracleTypeNumber :: DPIOracleType
   , djnNativeTypeNumber :: DPINativeType
   , djnValue :: Ptr ReadBuffer
-  }
-  deriving (Generic)
-  deriving anyclass (GStorable)
+  } deriving (Eq, Show)
+
+instance Storable DPIJsonNode where
+    sizeOf _ = sizeOf (undefined :: DPIOracleType)
+                + sizeOf (undefined :: DPINativeType)
+                    + sizeOf (undefined :: Ptr ReadBuffer)
+    alignment _ = alignment (undefined :: DPIOracleType)
+
+    peek ptr = do
+      let base = castPtr ptr
+      DPIJsonNode
+        <$> peek (base `plusPtr` 0) -- DPIOracleType
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIOracleType)) -- DPINativeType
+        <*> peek (base `plusPtr` sizeOf (undefined :: DPIOracleType)
+                                   `plusPtr` sizeOf (undefined :: DPINativeType)) -- Ptr ReadBuffer
+    poke ptr DPIJsonNode{..} = do
+      let base = castPtr ptr
+      poke (base `plusPtr` 0) djnOracleTypeNumber
+      poke (base `plusPtr` sizeOf (undefined :: DPIOracleType)) djnNativeTypeNumber
+      poke (base `plusPtr` sizeOf (undefined :: DPIOracleType)
+                    `plusPtr` sizeOf (undefined :: Ptr ReadBuffer)) djnValue
 
 data DPIJsonArray = DPIJsonArray
   { djaNumElements :: CUInt
diff --git a/test/Main.hs b/test/Main.hs
index 92861ad..dd9f374 100644
--- a/test/Main.hs
+++ b/test/Main.hs
@@ -22,8 +22,8 @@ import qualified Hedgehog.Gen as Gen
 import qualified Hedgehog.Range as Range
 import Test.Hspec (Spec, around, describe, hspec, it, shouldBe)
 import Test.Hspec.Hedgehog (hedgehog)
-import Foreign (peek, Storable, with)
-import Foreign.C.Types (CLong(..), CUInt(..))
+import Foreign (peek, Storable, with, nullFunPtr, nullPtr)
+import Foreign.C.Types (CLong(..), CUInt(..), CInt(..))
 import Foreign.C.String (newCString)
 
 import Database.Oracle.Simple
@@ -268,6 +268,126 @@ spec pool = do
             }
             result <- roundTripStorable dpixid
             result `shouldBe` dpixid
+        it "DPIPoolCreateParams" $ \_ -> do
+            someCString <- newCString "hello"
+            let dPIPoolCreateParams = DPIPoolCreateParams {
+                dpi_minSessions = CUInt 1
+              , dpi_maxSessions = CUInt 1
+              , dpi_sessionIncrement = CUInt 1
+              , dpi_pingInterval = CInt 1
+              , dpi_pingTimeout = CInt 1
+              , dpi_homogeneous = CInt 1
+              , dpi_externalAuth = CInt 1
+              , dpi_getMode = DPI_MODE_POOL_GET_WAIT
+              , dpi_outPoolName = someCString
+              , dpi_outPoolNameLength = CUInt 1
+              , dpi_timeout = CUInt 1
+              , dpi_waitTimeout = CUInt 1
+              , dpi_maxLifetimeSession = CUInt 1
+              , dpi_plsqlFixupCallback = someCString
+              , dpi_plsqlFixupCallbackLength = CUInt 1
+              , dpi_maxSessionsPerShard = CUInt 1
+              , dpi_accessTokenCallback = nullFunPtr
+              , dpi_accessTokenCallbackContext = nullPtr
+            }
+            result <- roundTripStorable dPIPoolCreateParams
+            result `shouldBe` dPIPoolCreateParams
+        it "ConnectionCreateParams" $ \_ -> do
+            someCString <- newCString "hello"
+            let dPIAppContext = DPIAppContext {
+              namespaceName = someCString
+            , namespaceNameLength = CUInt 1
+            , name = someCString
+            , nameLength = CUInt 1
+            , value = someCString
+            , valueLength = CUInt 1
+            }
+            let connectionCreateParams = ConnectionCreateParams {
+              authMode = DPI_MODE_AUTH_DEFAULT
+            , connectionClass = someCString
+            , connectionClassLength = CUInt 1
+            , purity = DPI_PURITY_DEFAULT
+            , newPassword = someCString
+            , newPasswordLength = CUInt 1
+            , appContenxt = dPIAppContext
+            , numAppContext = CUInt 1
+            , externalAuth = CInt 1
+            , externalHandle = nullPtr
+            , pool = DPIPool nullPtr
+            , tag = someCString
+            , tagLength = CUInt 1
+            , matchAnyTag = CInt 1
+            , outTag = someCString
+            , outTagLength = CUInt 1
+            , outTagFound = CInt 1
+            , shardingKeyColumn = DPIShardingKeyColumn nullPtr
+            , numShardingKeyColumns = 1
+            , superShardingKeyColumns = DPIShardingKeyColumn nullPtr
+            , numSuperShardingKeyColumns = 1
+            , outNewSession = CInt 1
+            }
+            result <- roundTripStorable connectionCreateParams
+            result `shouldBe` connectionCreateParams
+        it "DPICommonCreateParams" $ \_ -> do
+            someCString <- newCString "hello"
+            let dPICommonCreateParams = DPICommonCreateParams { 
+              createMode = DPI_MODE_CREATE_DEFAULT 
+            , encoding = someCString
+            , nencoding = someCString
+            , edition = someCString
+            , editionLength = CInt 1
+            , driverName = someCString
+            , driverNameLength = CInt 1
+            , sodaMetadataCache = 1
+            , stmtCacheSize = CInt 1
+          }
+            result <- roundTripStorable dPICommonCreateParams
+            result `shouldBe` dPICommonCreateParams
+        it "DPITimestamp" $ \_ -> do
+          let dPITimestamp = DPITimestamp {
+            year = 1
+          , month = 1
+          , day = 1
+          , hour = 1
+          , minute = 1
+          , second = 1
+          , fsecond = CUInt 1
+          , tzHourOffset = 1
+          , tzMinuteOffset = 1
+          }
+          result <- roundTripStorable dPITimestamp
+          result `shouldBe` dPITimestamp
+        it "DPIAppContext" $ \_ -> do
+          someCString <- newCString "hello"
+          let dPIAppContext = DPIAppContext {
+            namespaceName = someCString
+          , namespaceNameLength = CUInt 1
+          , name = someCString
+          , nameLength = CUInt 1
+          , value = someCString
+          , valueLength = CUInt 1
+          } 
+          result <- roundTripStorable dPIAppContext
+          result `shouldBe` dPIAppContext
+        it "DPIContextCreateParams" $ \_ -> do
+          someCString <- newCString "hello"
+          let dPIContextCreateParams = DPIContextCreateParams {
+            defaultDriverName = someCString
+          , defaultEncoding = someCString
+          , loadErrorUrl = someCString
+          , oracleClientLibDir = someCString
+          , oracleClientConfigDir = someCString
+          }
+          result <- roundTripStorable dPIContextCreateParams
+          result `shouldBe` dPIContextCreateParams
+        it "DPIJsonNode" $ \_ -> do
+          let dPIJsonNode = DPIJsonNode {
+                djnOracleTypeNumber = DPI_ORACLE_TYPE_NONE
+               , djnNativeTypeNumber = DPI_NATIVE_TYPE_INT64 
+               , djnValue = nullPtr
+            }
+          result <- roundTripStorable dPIJsonNode
+          result `shouldBe` dPIJsonNode
   where
     handleOracleError action = Exc.try @OracleError action >>= either (\_ -> pure ()) (\_ -> pure ())