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https://issues.apache.org/jira/browse/CASSANDRA-8730?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14348607#comment-14348607
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Benedict commented on CASSANDRA-8730:
-------------------------------------
bq. UUIDType is supposed to correctly compare TimeUUIDTypes
Regrettably, no it isn't. It actually has a different comparison logic for the
LSB of the TimeUUID.
bq. What is UUIDTypeTest.permute used to check for?
I've commented this method now, but it is to exhaustively check each of the
permutations of any given comparison point (i.e. each byte for all but the byte
containing the UUID type, and the top 4 bits only for that byte). I've also
updated the tests to randomise the input to the permutations, although
logically this should have no impact.
bq. Maybe resurrect the old versions to check that they are prior version
consistent in the unit tests. Maybe modify the test to use a seeded RNG with a
known seed and print it out so if there is a failure we can reproduce.
Sure, added to branch.
> Optimize UUIDType comparisons
> -----------------------------
>
> Key: CASSANDRA-8730
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8730
> Project: Cassandra
> Issue Type: Improvement
> Reporter: J.B. Langston
> Assignee: Benedict
> Fix For: 3.0
>
>
> Compaction is slow on tables using compound keys containing UUIDs due to
> being CPU bound by key comparison. [~benedict] said he sees some easy
> optimizations that could be made for UUID comparison.
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