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https://issues.apache.org/jira/browse/CASSANDRA-19755?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sam Tunnicliffe updated CASSANDRA-19755:
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Test and Documentation Plan: new and existing tests
Status: Patch Available (was: Open)
The issue is with sharing the same start time
({{RequestTime.startedAtNanos()}}) for the timing of each individual read
query, which was introduced by CASSANDRA-19534.
This results in accumulation so that the latency reported for query _n_
includes the latency of _(n-1)_ + _(n-2)_ + _(n-3)_ etc.
The fix is trivial and doesn't affect the other aspects of CASSANDRA-19534.
|4.1 patch:|[https://github.com/apache/cassandra/pull/3404]|
|5.0 patch:|[https://github.com/apache/cassandra/pull/3405]|
|trunk patch:|[https://github.com/apache/cassandra/pull/3406]|
There are 3 failures in the 4.1 CI results, but all of them are present without
this patch. Two are already tracked (CASSANDRA-17928, CASSANDRA-19702), but I
couldn't find an open JIRA for the {{ReadRepairTest}} dtest failure.
The jvm17 dtest timeouts on trunk are most likely down to CASSANDRA-19239, for
which a fix is coming soon.
> Coordinator read latency metrics are inflated for some queries
> --------------------------------------------------------------
>
> Key: CASSANDRA-19755
> URL: https://issues.apache.org/jira/browse/CASSANDRA-19755
> Project: Cassandra
> Issue Type: Bug
> Components: Observability/Metrics
> Reporter: Sam Tunnicliffe
> Assignee: Sam Tunnicliffe
> Priority: Normal
> Fix For: 4.1.x, 5.0-rc
>
>
> When a partition read is decomposed on the coordinator into multiple single
> partition read queries, the latency metric captured in StorageProxy can be
> artificially increased.
> This primarily affects reads where paging and aggregates are used or where an
> IN clause selects multiple partition keys.
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