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From Clint Kelly <clint.ke...@gmail.com>
Subject Any way to get a list of per-node token ranges using the DataStax Java driver?
Date Fri, 28 Feb 2014 18:27:38 GMT
Hi everyone,

I've been working on a rewrite of the Cassandra InputFormat for Hadoop 2
using the DataStax Java driver instead of the Thrift API.

I have a prototype working now, but there is one bit of code that I have
not been able to replace with code for the Java driver.  In the
InputFormat#getSplits method, the old code has a call like the following:

          map = client.describe_ring(ConfigHelper.getInputKeyspace(conf));

This gets a list of the distinct token ranges for the Cassandra cluster.

The rest of "getSplits" then takes these key ranges, breaks them up into
subranges (to match the user-specified input split size), and then gets the
replica nodes for the various token ranges (as the locations for the
splits).

Does anyone know how I can do the following with the native protocol?

   - Get the distinct token ranges for the C* cluster
   - Get the set of replica nodes for a given range of tokens?

I tried looking around in Cluster and Metadata, among other places, in the
API docs, but I didn't see anything that looked like it would do what I
want.

Thanks!

Best regards,
Clint

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