[
https://issues.apache.org/jira/browse/CASSANDRA-19497?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17895468#comment-17895468
]
Caleb Rackliffe commented on CASSANDRA-19497:
---------------------------------------------
For a bit more on why we see the above result, this is trunk:
!cpu-trunk-19497.png!
...while this is the patch with a batch size of 100:
!cpu-batch-100-19497.png!
Without the patch, we waste a lot of time in useless \{{isEmpty}} calls in
\{{queryMemtableAndDisk}}.
> ResultRetriever should batch clusterings/rows during SAI post-filtering reads
> -----------------------------------------------------------------------------
>
> Key: CASSANDRA-19497
> URL: https://issues.apache.org/jira/browse/CASSANDRA-19497
> Project: Cassandra
> Issue Type: Improvement
> Components: Feature/SAI
> Reporter: Caleb Rackliffe
> Assignee: Caleb Rackliffe
> Priority: Normal
> Fix For: 5.0.x, 5.x
>
> Attachments: alloc-trunk.html, cpu-batch-100-19497.png,
> cpu-trunk-19497.png, cpu-trunk.html, heap-flamegraph.html,
> wall-no-parked-threads.html
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> SAI currently creates and executes a {{SinglePartitionReadCommand}} for every
> {{PrimaryKey}} the index produces to read the corresponding row for
> post-filtering. Informed by the limits present in the read command itself, it
> should be possible to batch those reads w/ a {{ClusteringIndexNamesFilter}}
> in many fewer {{SinglePartitionReadCommands}}. When we have a handful of
> matches in a large partition, this seems like would involve many fewer seeks,
> less unnecessary object creation, etc.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
