[Flow] Session backends? Database Sessions?

[Christian Loock]

Hello,

how can I use Database or Memcache stored sessions? I tried to change 
the Caches.yaml

Flow_Session_Storage:
   backend: TYPO3\Flow\Cache\Backend\MemcachedBackend
   backendOptions:
     servers: ['localhost:11211']


But i get the following error:

#1370964558: The session storage cache must provide a backend 
implementing the IterableBackendInterface, but the given backend 
"TYPO3\Flow\Cache\Backend\MemcachedBackend" does not implement it.

Only Apc and FileSystem Backend implement this Interface right now it 
seems, but in the documentation is written that you can Use PDO and 
Memcache Session.

Thanks,

Christian