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From "chunhui shen (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-9488) Improve performance for small scan
Date Wed, 11 Sep 2013 03:11:52 GMT

    [ https://issues.apache.org/jira/browse/HBASE-9488?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13763905#comment-13763905
] 

chunhui shen commented on HBASE-9488:
-------------------------------------

Patch-v3 do the following changes:
1.Share the duplication code between ClientScanner & ClientSmallScanner, (Now, ClientSmallScanner
extends ClientScanner)
2.Support scan metrics in  ClientSmallScanner
3.Addressing the other comments from above and review board


Make the 0.94 branch patch as Lars mentioned, (The new method of HRegionInterface is named
'scan', seems more appropriate for me)
                
> Improve performance for small scan
> ----------------------------------
>
>                 Key: HBASE-9488
>                 URL: https://issues.apache.org/jira/browse/HBASE-9488
>             Project: HBase
>          Issue Type: Improvement
>          Components: Client, Performance, Scanners
>            Reporter: chunhui shen
>            Assignee: chunhui shen
>         Attachments: hbase-9488-94-v3.patch, HBASE-9488-trunk.patch, HBASE-9488-trunkV2.patch,
HBASE-9488-trunkV3.patch, test results.jpg
>
>
> review board:
> https://reviews.apache.org/r/14059/
> Now, one scan operation would call 3 RPC at least:
> openScanner();
> next();
> closeScanner();
> I think we could reduce the RPC call to one for small scan to get better performance
> Also using pread is better than seek+read for small scan (For this point, see more on
HBASE-7266)
> Implements such a small scan as the patch, and take the performance test as following:
> a.Environment´╝Ü
> patched on 0.94 version
> one regionserver; 
> one client with 50 concurrent threads;
> KV size:50/100;
> 100% LRU cache hit ratio;
> Random start row of scan
> b.Results:
> See the picture attachment
> *Usage:*
> Scan scan = new Scan(startRow,stopRow);
> scan.setSmall(true);
> ResultScanner scanner = table.getScanner(scan);
> Set the new 'small' attribute as true for scan, others are the same
>  

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