Any API for this?
What about query with conditions on key or values ?
I know there is a tap.py, which can dump all contents from Membase, but it it just a tool.
There isn't a way to do this do this Membase, but Couchbase 2.0 will add query support and will be released in late October. In the meantime you can download a developer preview on the Couchbase website to check out the new features.