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From Alain Rastoul <alf.mmm....@gmail.com>
Subject Re: How can I scale my read rate?
Date Fri, 24 Mar 2017 05:43:23 GMT
On 24/03/2017 01:00, Eric Stevens wrote:
> Assuming an even distribution of data in your cluster, and an even
> distribution across those keys by your readers, you would not need to
> increase RF with cluster size to increase read performance.  If you have
> 3 nodes with RF=3, and do 3 million reads, with good distribution, each
> node has served 1 million read requests.  If you increase to 6 nodes and
> keep RF=3, then each node now owns half as much data and serves only
> 500,000 reads.  Or more meaningfully in the same time it takes to do 3
> million reads under the 3 node cluster you ought to be able to do 6
> million reads under the 6 node cluster since each node is just
> responsible for 1 million total reads.
>
Hi Eric,

I think I got your point.
In case of really evenly distributed  reads it may (or should?) not make 
any difference,

But when you do not distribute well the reads (and in that case only),
my understanding about RF was that it could help spreading the load :
In that case, with RF= 4 instead of 3,  with several clients accessing keys
same key ranges, a coordinator could pick up one node to handle the request
in 4 replicas instead of picking up one node in 3 , thus having
more "workers" to handle a request ?

Am I wrong here ?

Thank you for the clarification


-- 
best,
Alain


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