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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-7279) Avoid copying the rowkey in RegionScanner, StoreScanner, and ScanQueryMatcher
Date Wed, 05 Dec 2012 05:29:01 GMT

    [ https://issues.apache.org/jira/browse/HBASE-7279?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13510287#comment-13510287
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Lars Hofhansl commented on HBASE-7279:
--------------------------------------

peeked is a local stack reference, so that should be ok

Re: how to verify the row cache is not needed... I looked at every caller of KeyValue.getRow().
These are either:
# tests
# not a hot code path (like getting the first key during a split)
# or from inspection it can be seen that the KV is not used twice

I think we're good on that front.

I am less certain about the timestamp cache, so I could put that back, and we leave that for
another patch (after removing the timestamp cache I was not observing any change - neither
speedup nor slowdown).

                
> 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
>
>
> 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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