Which key-value store has decent twisted API (nonblocking)?

I need a reliable K-V storage to be run in network. Main requirements:

1. Network conn开发者_StackOverflowectivity
2. has nonblocking twisted API
3. be reliable, production ready. No data loss
4. write performance is more important than read performance
5. support for distributed operation and failover would be great (So I just specify list of nodes)
6. java/ruby/erlang API would also be much appreciated

Additional bonus for having auto-increment for Key (PK), so SQL (MySQl? Postgres?) are also considered, do they have twisted drivers?

You could also Redis, with https://github.com/deldotdr/txRedis. redis is super fast, the only inconveninet is that it is memory based, meaning that your data has to fit in memory.

MongoDB sounds like a really good fit: http://api.mongodb.org/python/1.8.1%2B/index.html

I haven't really played with Twisted yet but Mongo fulfils all of your listed requirements.