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Jeff Jirsa commented on CASSANDRA-7296:
---------------------------------------
{quote}
First, I'm not even entirely sure than letting the dynamic snitch bypass the
coordinator if it's a replica is a good idea in the first place. Everyone more
or less agree that doing token-aware routing is a good thing nowadays, and it's
certainly confusing that the dynamic snitch may screw that up. If the dynamic
snitch was a perfect and instantaneous view of latencies, then that could make
sense, but it's not. Anyway, I think it's worth at least evaluating making even
the dynamic snitch always pick the local node if it's a replica, as I'm not
sure the benefit of not doing so outweigh the confusion it creates.
{quote}
Emotionally, I want this to be the right answer (principle of least
astonishment), but I don't think it is. I'm concerned it will prove to be a
step backwards in real clusters, where coordinator disk latencies may truly
jump up up significantly (imagine all compaction threads running scrub/cleanup,
where not only is the disk likely completely utilized, but the # of sstables on
disk grows because all compaction threads are in use, so reads are more
expensive than normal - in this case, dsnitch DOES save us, and implementing
this type of change would be very hard to work around in production with most
drivers).
> Add CL.COORDINATOR_ONLY
> -----------------------
>
> Key: CASSANDRA-7296
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7296
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Tupshin Harper
>
> For reasons such as CASSANDRA-6340 and similar, it would be nice to have a
> read that never gets distributed, and only works if the coordinator you are
> talking to is an owner of the row.
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