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Date: Wed, 21 Sep 2016 22:44:20 +0000 (UTC)
From: "Josh Elser (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (ACCUMULO-4468)
 accumulo.core.data.Key.equals(Key, PartialKey) improvement
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archived-at: Wed, 21 Sep 2016 22:44:22 -0000


    [ https://issues.apache.org/jira/browse/ACCUMULO-4468?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15511430#comment-15511430 ] 

Josh Elser commented on ACCUMULO-4468:
--------------------------------------

Looking at the repo, it's important that the code is not doing a {{previous.equals(next)}} but actually {{previous.equals(next, PartialKey.ROW_COLFAM)}}.

> accumulo.core.data.Key.equals(Key, PartialKey) improvement
> ----------------------------------------------------------
>
>                 Key: ACCUMULO-4468
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-4468
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 1.8.0
>            Reporter: Will Murnane
>            Priority: Trivial
>              Labels: newbie, performance
>         Attachments: benchmark.tar.gz, key_comparison.patch
>
>
> In the Key.equals(Key, PartialKey) overload, the current method compares starting at the beginning of the key, and works its way toward the end. This functions correctly, of course, but one of the typical uses of this method is to compare adjacent rows to break them into larger chunks. For example, accumulo.core.iterators.Combiner repeatedly calls this method with subsequent pairs of keys.
> I have a patch which reverses the comparison order. That is, if the method is called with ROW_COLFAM_COLQUAL_COLVIS, it will compare visibility, cq, cf, and finally row. This (marginally) improves the speed of comparisons in the relatively common case where only the last part is changing, with less complex code.


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