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https://issues.apache.org/jira/browse/CASSANDRA-13508?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16215821#comment-16215821
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Blake Eggleston commented on CASSANDRA-13508:
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Coming back to this, I think making {{system.paxos}} configurable might be the
wrong approach. The system keyspaces typically store system metadata, where the
data and query volumes are low enough that the table configuration shouldn’t be
a concern for operators. The paxos table (and the batch log, but let's stick to
the paxos table for now) is directly involved in the processing of queries. In
applications that are heavy cas users, it can be the most heavily used table in
the cluster.
Maybe it would be better to treat these tables more like index tables, where
each table involved in paxos operations gets it’s own local sidecar table? We
could either then make the paxos table inherit the compaction settings from
it’s parent table, or we could enable separately tuning the paxos table with a
{{paxos_compaction}} schema option or something.
Any thoughts on this?
> Make system.paxos table compaction strategy configurable
> --------------------------------------------------------
>
> Key: CASSANDRA-13508
> URL: https://issues.apache.org/jira/browse/CASSANDRA-13508
> Project: Cassandra
> Issue Type: Improvement
> Components: Coordination
> Reporter: Jay Zhuang
> Assignee: Jay Zhuang
> Labels: core, paxos
> Fix For: 4.0, 4.x
>
> Attachments: test11.png, test2.png
>
>
> The default compaction strategy for {{system.paxos}} table is LCS for
> performance reason: CASSANDRA-7753. But for CAS heavily used cluster, the
> system is busy with {{system.paxos}} compaction.
> As the data in {{paxos}} table are TTL'ed, TWCS might be a better fit. In our
> test, it significantly reduced the number of compaction without impacting the
> latency too much:
> !test11.png!
> The time window for TWCS is set to 2 minutes for the test.
> Here is the p99 latency impact:
> !test2.png!
> the yellow one is LCS, the purple one is TWCS. Average p99 has about 10%
> increase.
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