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https://issues.apache.org/jira/browse/CASSANDRA-16465?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17329095#comment-17329095
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Paulo Motta edited comment on CASSANDRA-16465 at 4/22/21, 2:05 PM:
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{quote}I do have some doubt if the behavior is related to CASSANDRA-15690
because the impact on the read latency can be observed immediately after
switching the Cassandra version. No need to wait for partitions being deleted
or not.
{quote}
If this is caused by CASSANDRA-15690 the performance regression should be
observed immediately after switching version, even if there are no partition
deletions.
{quote}I have to object. In our setup it does happen with 3.11.7. With 3.11.6
performance is still ok.
{quote}
In order to rule out CASSANDRA-15690 would you be willing to test a jar of
[this
branch|https://github.com/pauloricardomg/cassandra/tree/cassandra-3.11.7-without-CASSANDRA-15690]
? This is basically 3.11.7 without CASSANDRA-15690. You can clone this repo
and then generate the jar with -{{mvn jar}}- *{{ant jar}}* and then replace
your install {{cassandra-all*.jar}} with the newly created jar. If the
performance issue is fixed than we can safely assume it was caused by the
removal of the optimization from CASSANDRA-15690.
was (Author: paulo):
bq. I do have some doubt if the behavior is related to CASSANDRA-15690 because
the impact on the read latency can be observed immediately after switching the
Cassandra version. No need to wait for partitions being deleted or not.
If this is caused by CASSANDRA-15690 the performance regression should be
observed immediately after switching version, even if there are no partition
deletions.
bq. I have to object. In our setup it does happen with 3.11.7. With 3.11.6
performance is still ok.
In order to rule out CASSANDRA-15690 would you be willing to test a jar of
[this
branch|https://github.com/pauloricardomg/cassandra/tree/cassandra-3.11.7-without-CASSANDRA-15690]
? This is basically 3.11.7 without CASSANDRA-15690. You can clone this repo
and then generate the jar with {{mvn jar}} and then replace your install
{{cassandra-all*.jar}} with the newly created jar. If the performance issue is
fixed than we can safely assume it was caused by the removal of the
optimization from CASSANDRA-15690.
> Increased Read Latency With Cassandra >= 3.11.7
> -----------------------------------------------
>
> Key: CASSANDRA-16465
> URL: https://issues.apache.org/jira/browse/CASSANDRA-16465
> Project: Cassandra
> Issue Type: Bug
> Components: Legacy/Local Write-Read Paths
> Reporter: Ahmed ELJAMI
> Priority: Normal
> Fix For: 3.11.11
>
>
> After upgrading Cassandra from 3.11.3 to 3.11.9, Cassandra read latency 99%
> increased significantly. Getting back to 3.11.3 immediately fixed the issue.
> I have observed "SStable reads" increases after upgrading to 3.11.9.
> The same behavior was observed by some other users:
> [https://www.mail-archive.com/[email protected]/msg61247.html]
> According to Paulo Motta's comment, this behavior may be caused by
> https://issues.apache.org/jira/browse/CASSANDRA-15690 which was introduced on
> 3.11.7 and removed an optimization that may cause a correctness issue when
> there are partition deletions.
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