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https://issues.apache.org/jira/browse/CASSANDRA-4705?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vijay updated CASSANDRA-4705:
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Attachment: 0001-CASSANDRA-4705.patch
Hi Jonathan, the custom value is kind of better in the cases where users can
say, My SLA is 20 MS and i want co-ordinator to retry the reads after 15 MS, or
more aggressively retry after 10 MS.
Attached patch supports the following:
- ALL
- auto95 (Default)
- auto98
- auto99
- auto999
- autoMean
- NONE (current behavior)
> Speculative execution for CL_ONE
> --------------------------------
>
> Key: CASSANDRA-4705
> URL: https://issues.apache.org/jira/browse/CASSANDRA-4705
> Project: Cassandra
> Issue Type: Improvement
> Affects Versions: 1.2.0
> Reporter: Vijay
> Assignee: Vijay
> Priority: Minor
> Attachments: 0001-CASSANDRA-4705.patch
>
>
> When read_repair is not 1.0, we send the request to one node for some of the
> requests. When a node goes down or when a node is too busy the client has to
> wait for the timeout before it can retry.
> It would be nice to watch for latency and execute an additional request to a
> different node, if the response is not received within average/99% of the
> response times recorded in the past.
> CASSANDRA-2540 might be able to solve the variance when read_repair is set to
> 1.0
> 1) May be we need to use metrics-core to record various Percentiles
> 2) Modify ReadCallback.get to execute additional request speculatively.
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