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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-3928) Some potential performance improvements to Bytes/KeyValue
Date Fri, 27 May 2011 18:50:47 GMT

    [ https://issues.apache.org/jira/browse/HBASE-3928?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13040376#comment-13040376
] 

stack commented on HBASE-3928:
------------------------------

+1 on commit to TRUNK.  Can only improve things.  We'll be profiling 0.92 before commit so
if a problem, a newly-introduced hotspot, we'll see it then (I'd doubt that this optimization
would show in YCSB -- not unless it made stuff really bad, or really good which I don't think
is going to be happening here).

Odd we don't cache this Bytes.toBytes("MAX_SEQ_ID_KEY") and the other TIMERANGE constant that
follows.



> Some potential performance improvements to Bytes/KeyValue
> ---------------------------------------------------------
>
>                 Key: HBASE-3928
>                 URL: https://issues.apache.org/jira/browse/HBASE-3928
>             Project: HBase
>          Issue Type: Improvement
>    Affects Versions: 0.92.0
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>            Priority: Minor
>             Fix For: 0.92.0
>
>         Attachments: hbase-3928.txt
>
>
> We use Bytes.compareTo() a lot where we could be using a more efficient equals() method.
The trick that makes equals() faster than compareTo is that we can short-circuit two common
cases:
> Case 1) the length is not the same - only need to do one comparison
> Case 2) the two arrays have the same length and a common prefix: compare the last byte
first, since it's the one most likely to differ (given we are usually comparing adjacent sorted
data).

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