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https://issues.apache.org/jira/browse/CASSANDRA-13611?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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C. Scott Andreas updated CASSANDRA-13611:
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Summary: Reduce cost/frequency of digest mismatches in quorum reads (was:
Digest mismatch in Quorum read)
> Reduce cost/frequency of digest mismatches in quorum reads
> ----------------------------------------------------------
>
> Key: CASSANDRA-13611
> URL: https://issues.apache.org/jira/browse/CASSANDRA-13611
> Project: Cassandra
> Issue Type: Improvement
> Components: Coordination
> Reporter: Dikang Gu
> Assignee: Dikang Gu
> Priority: Major
> Fix For: 4.x
>
>
> In current implementation, when we issue a quorum read, C* will send full
> data request to one replica, and send digest requests to other replicas. If
> the digest mismatch, C* will send another round of full data request to all
> replicas.
> In our environment, we find in P99 case, digest are always mismatch, so we
> are doing 2 round trips of requests in P99, which hurts our P99 latency a lot.
> We propose that in quorum read case, we send full data replicas to the quorum
> replicas directly, reconcile them and send back to client. In our experiment
> , it reduced the P99 latency by 20% ~ 30%.
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