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https://issues.apache.org/jira/browse/CASSANDRA-1043?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12863512#action_12863512
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Nicolas Labrot commented on CASSANDRA-1043:
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I will just add a comment on the test. Like the optimisation uses the internal
structure of Jug UUID it should be valusable to add a test on it.
for example with asserts on value of UUID.INDEX_CLOCK_HI, UUID.INDEX_CLOCK_MID
and INDEX_CLOCK_MID.INDEX_CLOCK_LO
> Faster UUID comparisons
> -----------------------
>
> Key: CASSANDRA-1043
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1043
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: James Golick
> Assignee: James Golick
> Priority: Minor
> Fix For: 0.7
>
> Attachments: faster-uuid-compare-v3.diff, faster_uuid_compare.diff,
> patch-v2-with-tests.diff
>
>
> As I explained on the mailing list, doing slice queries on CFs that are
> sorted by TimeUUIDType gets slower as the value of count increases. According
> to my profiles, this is largely due to the fact that ConcurrentSkipListMap
> calls the comparator very frequently, which is extremely inefficient. In
> order to compare two UUIDs, it has to materialize them both in to
> java.util.UUID objects which is quite slow. The more UUIDs to compare, the
> slower it is.
> Attached is a patch that compares UUIDs by extracting the timestamp directly
> from the byte[] representation. According to my tests, it's close to a 50%
> performance improvement.
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