On Wed, Feb 5, 2014 at 2:45 PM, Sameer Farooqui <sam...@blueplastic.com>wrote:
> Does the new DataStax Python Driver 1.0.0 intelligently choose a > coordinator that is also likely to be a replica partner for that row-key > when using vnodes in C* 2.0? If so, how does it do it... just hash the > row-key and see which partition range it falls in and which node owns that > range? > Basically, yes. > > Here is all the DataStax blog post says on this topic: > > "When a query is executed, a list of nodes to attempt the query against is > generated. If the query fails against the first node in the list, the > second node may be used, and so on. When sending a query to a node, the > driver selects the least-utilized connection from that node's connection > pool and issues the query." > > How is that list of nodes generated? > It depends on what LoadBalancingPolicy you pick: http://datastax.github.io/python-driver/api/cassandra/policies.html#load-balancing . By default, the driver does not try to use a replica as the coordinator; you have to wrap the load balancing policy with TokenAwarePolicy to enable that. > > > Also, does the current version of the DS Java driver also intelligently > choose a coordinator that is likely to already hold a replica of the row > key? > The Java driver behavior is almost exactly the same. P.S. There is a mailing list dedicated to the python driver: https://groups.google.com/a/lists.datastax.com/forum/#!forum/python-driver-user -- Tyler Hobbs DataStax <http://datastax.com/>
