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Posted to commits@cassandra.apache.org by "Stu Hood (JIRA)" <ji...@apache.org> on 2011/09/08 23:34:09 UTC

[jira] [Commented] (CASSANDRA-2890) Randomize (to some extend) the choice of the first replica for counter increment

    [ https://issues.apache.org/jira/browse/CASSANDRA-2890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13100715#comment-13100715 ] 

Stu Hood commented on CASSANDRA-2890:
-------------------------------------

Randomizing the first replica will break dynamic snitch behaviour. If we're assuming:
1) everyone uses the dynamic snitch
2) some folks perform nearly 100% writes, and very few client reads
...would it be better to start recording the replicate-on-writes latencies in the dynamic snitch, so that the first replica will be chosen based on latency, rather than raw snitch scores?

> Randomize (to some extend) the choice of the first replica for counter increment
> --------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-2890
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2890
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>    Affects Versions: 0.8.0
>            Reporter: Sylvain Lebresne
>            Assignee: Sylvain Lebresne
>            Priority: Minor
>              Labels: counters
>             Fix For: 1.1
>
>
> Right now, we choose the first replica for a counter increments based solely on what the snitch returns. If the clients requests are well balanced over the cluster and the snitch not ill configured, this should not be a problem, but this is probably too strong an assumption to make.
> The goal of this ticket is to change this to choose a random replica in the current data center instead.

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