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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-2364) Record dynamic snitch latencies for counter writes
Date Tue, 22 Mar 2011 18:18:05 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-2364?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13009756#comment-13009756
] 

Jonathan Ellis commented on CASSANDRA-2364:
-------------------------------------------

Disagree that we want to pollute read latency info w/ writes (which are almost impossible
to slow down, so you're basically just measuring network latency and mixing that low-value
info w/ the high-value signal the reads).

Also: always choosing the closest node to be the write coordinator seems like you lose the
benefits of counter partitioning.

Suggest using static snitch info to prefer a coordinator from the local DC and randomly pick
from those.

> Record dynamic snitch latencies for counter writes
> --------------------------------------------------
>
>                 Key: CASSANDRA-2364
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2364
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Stu Hood
>            Priority: Minor
>              Labels: counters
>             Fix For: 0.8
>
>
> The counter code chooses a single replica to coordinate a write, meaning that it should
be subject to dynamic snitch latencies like a read would be. This already works when there
are reads going on, because the dynamic snitch read latencies are used to pick a node to coordinate,
but when there are no reads going on (such as during a backfill) the latencies do not adjust.

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