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https://issues.apache.org/jira/browse/CASSANDRA-8546?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dominic Letz updated CASSANDRA-8546:
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Attachment: cassandra-2.0.11-8546.txt
Attaching a patch that replaces the plain arrays with a GapList from the
brownies java collections library (apache 2.0 license).
Passes ant test
Improves performance in the worse case scenarios like this on my notebook:
50k deletes: 7 seconds without patch 700ms with patch.
100k deletes: 3 minutes without patch 3 seconds with patch.
> RangeTombstoneList becoming bottleneck on tombstone heavy tasks
> ---------------------------------------------------------------
>
> Key: CASSANDRA-8546
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8546
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Environment: 2.0.11 / 2.1
> Reporter: Dominic Letz
> Priority: Critical
> Fix For: 2.0.12
>
> Attachments: cassandra-2.0.11-8546.txt, tombstone_test.tgz
>
>
> I would like to propose a change of the data structure used in the
> RangeTombstoneList to store and insert tombstone ranges to something with at
> least O(log N) insert in the middle and at near O(1) and start AND end. Here
> is why:
> When having tombstone heavy work-loads the current implementation of
> RangeTombstoneList becomes a bottleneck with slice queries.
> Scanning the number of tombstones up to the default maximum (100k) can take
> up to 3 minutes of how addInternal() scales on insertion of middle and start
> elements.
> The attached test shows that with 50k deletes from both sides of a range.
> INSERT 1...110000
> flush()
> DELETE 1...50000
> DELETE 110000...60000
> While one direction performs ok (~400ms on my notebook):
> {code}
> SELECT * FROM timeseries WHERE name = 'a' ORDER BY timestamp DESC LIMIT 1
> {code}
> The other direction underperforms (~7seconds on my notebook)
> {code}
> SELECT * FROM timeseries WHERE name = 'a' ORDER BY timestamp ASC LIMIT 1
> {code}
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