On Thu, Mar 3, 2011 at 8:34 PM, Suraj Varma <svarma...@gmail.com> wrote: > This is interesting - so, doesn't asynchbase have any dependency on hbase > jar or hadoop jar? How does it achieve this version independence?
Yes asynchbase doesn't depend on the HBase jar or Hadoop jar. It's just a re-implementation of the HBase client, but done differently. The version independence is achieved by using the getProtocolVersion RPC. Depending on the version of the server, the client will adjust its behavior to match the server's expectations. > Also - does this mean that we could just swap the zookeeper quorum to that > of a different version cluster and achieve a no outage upgrade (from > client's perspective)? Theoretically, yes. In practice, bear in mind that HBase has a bad track record of breaking backward compatibility between virtually every release (even minor ones), although they often bump the protocol version number even though there are no client-visible API changes (e.g. because only some internal APIs used by the master or other administrative APIs irrelevant for the client changed). For a long time asynchbase didn't actually care what version the server was, because the subset of the API it was using was fairly stable. Having said that, I'm hopeful that since HBase is becoming increasingly popular and prevalent among "NoSQL" databases, the versions are going to be increasingly backward compatible and changes will be implemented in such a way that the client will be able to detect different server versions and adjust itself accordingly. Eventually, I hope it'll be possible to have rolling upgrades of a cluster, at least between minor versions. -- Benoit "tsuna" Sigoure Software Engineer @ www.StumbleUpon.com
