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From "Matt Corgan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-7279) Avoid copying the rowkey in RegionScanner, StoreScanner, and ScanQueryMatcher
Date Wed, 05 Dec 2012 07:18:58 GMT

    [ https://issues.apache.org/jira/browse/HBASE-7279?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13510331#comment-13510331
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Matt Corgan commented on HBASE-7279:
------------------------------------

Yeah - we can't do it with the current immutable KeyValues because of garbage and/or memory
bloat, but the encoded scanners reuse a backing object where you can cache as many values
as you want because you're reusing everything.  See BufferedDataBlockEncoder.SeekerState (which
i'm making implement the Cell interface).  The SeekerState gets reused as the scanner trots
along.
                
> Avoid copying the rowkey in RegionScanner, StoreScanner, and ScanQueryMatcher
> -----------------------------------------------------------------------------
>
>                 Key: HBASE-7279
>                 URL: https://issues.apache.org/jira/browse/HBASE-7279
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Lars Hofhansl
>            Assignee: Lars Hofhansl
>             Fix For: 0.96.0, 0.94.4
>
>         Attachments: 7279-0.94.txt, 7279-0.94-v2.txt, 7279-0.94-v3.txt, 7279-0.96-v1.txt
>
>
> Did some profiling again.
> I we can gain some performance [1] when passing buffer, rowoffset, and rowlength instead
of making a copy of the row key.
> That way we can also remove the row key caching (and this patch also removes the timestamps
caching). Considering the sheer number in which we create KVs, every byte save is good.
> [1] (15-20% when data is in the block cache we setup a Filter such that only a single
row is returned to the client).

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