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From Ian Kallen <>
Subject Re: Updating (as opposed to just setting) Cassandra data via Hadoop
Date Fri, 07 May 2010 13:54:25 GMT
On 5/6/10 3:26 PM, Stu Hood wrote:
> Ian: I think that as get_range_slice gets faster, the approach that Mark was heading
toward may be considerably more efficient than reading the old value in the OutputFormat.
Interesting, I'm trying to understand the performance impact of the 
different ways to do this. Under Mark's approach, the prior values are 
pulled out of Cassandra in the mapper in bulk, then merged and written 
back to Cassandra in the reducer; the get_range_slice is faster than the 
individual row fetches that my approach does in the reducer. Is that 
what you mean or are you referring to something else?

Ian Kallen
vox: 925.385.8426

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