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https://issues.apache.org/jira/browse/CASSANDRA-8730?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14311986#comment-14311986
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Benedict commented on CASSANDRA-8730:
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bq. while TimeUUIDType uses ByteBuffer.compareTo which does a byte-signed
comparison
Good catch. I would still prefer that these extend each other, because the
cleanup is I think useful and makes it more obvious they are interdependent.
But this does eliminate some of the benefit, and perhaps this should be done in
a separate patch.
bq. Also, as even subtly changing the comparison would have desastrous
consequence, it would be nice to add a few tests that checks that old and new
versions compare the same way
Sure. The current code already does some randomized testing, that I was
planning to up the ante on and run a burn test in, but there's no reason not to
introduce some specific tests for a mutation of each conditional comparison in
the old code.
bq. As an aside, I personally think this should be targeted at 3.0 (it's not a
bug fix).
I have no particular position on this. It's a pretty contained change though,
so I would be comfortable introducing it in 2.1, but have no strong preference
versus 3.0. Whilst I was a bit careless in the extension, I was careful in the
UUIDType rewrite to ensure the semantics of the comparison are the same. The
only semantic change I've introduced here is to assert the size of the data is
_exactly_ 16 bytes, or zero, which I'm comfortable omitting, or delaying, or
introducing. However anybody else feels strongly.
> 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: 2.1.4
>
>
> 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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