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Posted to commits@cassandra.apache.org by "Kanthi Subramanian (Jira)" <ji...@apache.org> on 2021/10/23 23:00:08 UTC
[jira] [Commented] (CASSANDRA-14160) maxPurgeableTimestamp should
traverse tables in order of minTimestamp
[ https://issues.apache.org/jira/browse/CASSANDRA-14160?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17433379#comment-17433379 ]
Kanthi Subramanian commented on CASSANDRA-14160:
------------------------------------------------
[~e.dimitrova], [~brandon.williams] is this issue still valid, would be a good experience to work on SSTables.
> maxPurgeableTimestamp should traverse tables in order of minTimestamp
> ---------------------------------------------------------------------
>
> Key: CASSANDRA-14160
> URL: https://issues.apache.org/jira/browse/CASSANDRA-14160
> Project: Cassandra
> Issue Type: Bug
> Components: Local/Compaction
> Reporter: Josh Snyder
> Priority: Normal
> Labels: performance
> Fix For: 4.x
>
>
> In maxPurgeableTimestamp, we iterate over the bloom filters of each overlapping SSTable. Of the bloom filter hits, we take the SSTable with the lowest minTimestamp. If we kept the SSTables in sorted order of minTimestamp, then we could short-circuit the operation at the first bloom filter hit, reducing cache pressure (or worse, I/O) and CPU time.
> I've written (but not yet benchmarked) [some code|https://github.com/hashbrowncipher/cassandra/commit/29859a4a2e617f6775be49448858bc59fdafab44] to demonstrate this possibility.
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