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From Leonid Ilyevsky <lilyev...@mooncapital.com>
Subject Batch update efficiency with composite key
Date Wed, 18 Jul 2012 13:18:42 GMT
I have a question about efficiency of updates to a CF with composite key.

Let say I have 100 of logical rows to update, and they all belong to the same physical wide
row. In my naïve understanding (correct me if I am wrong), in order to update a logical row,
Cassandra has to retrieve the whole physical row, add columns to it, and put it back. So I
put all my 100 updates in a batch and send it over. Would Cassandra be smart enough to recognize
that they all belong to one physical row, retrieve it once, do all the updates and put it
back once? Is my batch thing even relevant in this case? What happens if I just send updates
one by one?

I want to understand why I should use batches. I don't really care about one timestamp for
all records, I only care about efficiency. So I thought, I want to at least save on the number
of remote calls, but I also wonder what happens on Cassandra side.


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