That kind of defeats the purpose of what's being proposed. Why wouldn't you just store all of the data in memcache instead of just the key? If you lost the me

That kind of defeats the purpose of what's being proposed. Why wouldn't you just store all of the data in memcache instead of just the key? If you lost the memcache you're losing all of your sessions either way. One way you could get around it would be some kind of time based key like an RSA token. That way each of the servers would know all of the tokens a priori and you only accept that token for a limited period of time. Not perfect, but you still benefit from not being tied to your database.