[jira] Updated: (CASSANDRA-1043) Faster UUID comparisons

["James Golick (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-1043?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

James Golick updated CASSANDRA-1043:
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    Attachment: faster_uuid_compare.diff

> 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
>            Priority: Minor
>         Attachments: faster_uuid_compare.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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