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From Brian Tarbox <>
Subject do all nodes actually send the data to the coordinator when doing a read?
Date Fri, 25 Jul 2014 20:12:46 GMT
We're considering a C* setup with very large columns and I have a question
about the details of read.

I understand that a read request gets handled by the coordinator which
sends read requests to <quorum> of the nodes holding replicas of the data,
and once <quorum> nodes have replied with consistent data it is returned to
the client.

My understanding is that each of the nodes actually sends the full data
being requested to the coordinator (which in the case of very large columns
would involve lots of network traffic).  Is that right?

The alternative (which I don't think is the case but I've been asked to
verify) is that the replicas first send meta-data to the coordinator which
then asks one replica to send the actual data.  Again, I don't think this
is the case but was asked to confirm.



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