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https://issues.apache.org/jira/browse/CASSANDRA-21637?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dmitry Konstantinov updated CASSANDRA-21637:
--------------------------------------------
Fix Version/s: 6.0-alpha3
7.0
(was: 7.x)
(was: 6.0.x)
Source Control Link:
https://github.com/apache/cassandra/commit/508ea049629c931f54b509e36438b089aef8fd1a
Resolution: Fixed
Status: Resolved (was: Ready to Commit)
> Avoid double chunk read for BTI small partitions during a select query
> execution
> --------------------------------------------------------------------------------
>
> Key: CASSANDRA-21637
> URL: https://issues.apache.org/jira/browse/CASSANDRA-21637
> Project: Apache Cassandra
> Issue Type: Improvement
> Components: Local/SSTable
> Reporter: Dmitry Konstantinov
> Assignee: Dmitry Konstantinov
> Priority: Normal
> Fix For: 6.0-alpha3, 7.0
>
> Attachments: CASSANDRA-21637-trunk-ci_summary.html,
> image-2026-09-02-15-59-03-586.png, image-2026-09-06-17-35-44-923.png,
> image-2026-09-12-13-04-44-694.png, noser_base_btiNoDoubleReadAfter_cpu.html,
> noser_base_btiNoDoubleReadAfter_fileCacheDisabled_cpu.html,
> noser_base_btiNoDoubleReadAfter_fileCacheDisabled_wall.html,
> noser_base_btiNoDoubleReadAfter_fileCacheEnabled_cpu.html,
> noser_base_btiNoDoubleReadAfter_fileCacheEnabled_wall.html,
> noser_base_btiNoDoubleReadBefore_cpu.html,
> noser_base_btiNoDoubleReadBefore_fileCacheDisabled_cpu.html,
> noser_base_btiNoDoubleReadBefore_fileCacheDisabled_wall.html,
> noser_base_btiNoDoubleReadBefore_fileCacheEnabled_cpu.html,
> noser_base_btiNoDoubleReadBefore_fileCacheEnabled_wall.html
>
> Time Spent: 50m
> Remaining Estimate: 0h
>
> BtiTableReader.getExactPosition() opens a data-file reader to verify the
> partition key when the trie payload is negative (means the partition small
> enough to have no row index entry). It then closed that reader, and
> AbstractSSTableIterator immediately reopened the same file at the same
> position. So, we read the same chunk twice in such scenario as well as run
> LZ4 decompression and CRC32 check twice. We can re-use the reader to avoid it.
> !image-2026-09-02-15-59-03-586.png|width=600!
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