Don't forget that reading at ONE may not mean that only 1 replica is involved
in the request.
Any get or multiget (not range scan) read that runs with ReadRepair enabled
will be sent to all UP replicas. If the RR is disabled it will only be sent to
as many replicas as needed for the CL. For CL ONE the RR happens async to the
request, this normally means after the initial request has returned.
So running with CL One *may* make the request return a little faster, but if RR
is enabled you are still asking the cluster to do the same amount of work. And
if the client(s) is running in a tight loop reading at ONE makes is easier for
the client to overload the server as it can send more work before the server
has really finished the previous request.
You can adjust the probability the RR will run in the yaml config.
Hope that helps.
-----------------
Aaron Morton
Freelance Cassandra Developer
@aaronmorton
http://www.thelastpickle.com
On 10 Jun 2011, at 00:37, Richard Low wrote:
> 2011/6/9 Héctor Izquierdo Seliva <izquie...@strands.com>:
>
>> Yeah, but if I have RF=3 then there are three nodes that can answer the
>> request right?
>
> Yes, if you're happy to read ConsistencyLevel.ONE.
