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From "Chao Shi (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-9000) Linear reseek in Memstore
Date Thu, 31 Oct 2013 05:54:27 GMT

    [ https://issues.apache.org/jira/browse/HBASE-9000?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13809958#comment-13809958
] 

Chao Shi commented on HBASE-9000:
---------------------------------

I re-ran the benchmark program, and get the following numbers. (As there the overhead is not
significant, the numbers below are the median of 5 runs.)

||operation||trunk||w/ patch (n=5)||w/patch (n=20)
|reseek to next row|5.82 us|5.76 us|6.14 us|
|reseek to next column|3.397 us|0.596 us|0.572 us|

(where n is the limit of max linear seeks)

numbers are varying within +-10% between each run.

bq. -1 findbugs. The patch appears to introduce 1 new Findbugs (version 1.3.9) warnings.
bq. -1 site. The patch appears to cause mvn site goal to fail.

These two QA -1s seem not to be related with my patch.

> Linear reseek in Memstore
> -------------------------
>
>                 Key: HBASE-9000
>                 URL: https://issues.apache.org/jira/browse/HBASE-9000
>             Project: HBase
>          Issue Type: Improvement
>    Affects Versions: 0.89-fb
>            Reporter: Shane Hogan
>            Priority: Minor
>             Fix For: 0.89-fb
>
>         Attachments: hbase-9000-benchmark-program.patch, hbase-9000.patch, hbase-9000-port-fb.patch
>
>
> This is to address the linear reseek in MemStoreScanner. Currently reseek iterates over
the kvset and the snapshot linearly by just calling next repeatedly. The new solution is to
do this linear seek up to a configurable maximum amount of times then if the seek is not yet
complete fall back to logarithmic seek.



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