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https://issues.apache.org/jira/browse/CASSANDRA-2034?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13080137#comment-13080137
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Jonathan Ellis commented on CASSANDRA-2034:
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bq. The only issue is if too many mutations queue up you might OOM but this is
the same problem we currently we have with the write stage
Right. Either way worst case is already "you need to be able to buffer up to
rpc_timeout's worth of writes in memory."
bq. if you use a Expiring map you should add a onExpiration hook to write the
hint locally for the replicas that never responded to the Mutation
I'm not sure you want a separate ExpiringMap from the one you already have in
MS. Might make for weird corner cases. But that's an implementation detail;
the approach is sound.
> Make Read Repair unnecessary when Hinted Handoff is enabled
> -----------------------------------------------------------
>
> Key: CASSANDRA-2034
> URL: https://issues.apache.org/jira/browse/CASSANDRA-2034
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Jonathan Ellis
> Assignee: Patricio Echague
> Fix For: 1.0
>
> Attachments: 2034-formatting.txt, CASSANDRA-2034-trunk-v2.patch,
> CASSANDRA-2034-trunk-v3.patch, CASSANDRA-2034-trunk-v4.patch,
> CASSANDRA-2034-trunk-v5.patch, CASSANDRA-2034-trunk-v6.patch,
> CASSANDRA-2034-trunk-v7.patch, CASSANDRA-2034-trunk.patch
>
> Original Estimate: 8h
> Remaining Estimate: 8h
>
> Currently, HH is purely an optimization -- if a machine goes down, enabling
> HH means RR/AES will have less work to do, but you can't disable RR entirely
> in most situations since HH doesn't kick in until the FailureDetector does.
> Let's add a scheduled task to the mutate path, such that we return to the
> client normally after ConsistencyLevel is achieved, but after RpcTimeout we
> check the responseHandler write acks and write local hints for any missing
> targets.
> This would making disabling RR when HH is enabled a much more reasonable
> option, which has a huge impact on read throughput.
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