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From "chunhui shen (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-9488) Improve performance for small scan
Date Tue, 10 Sep 2013 08:30:52 GMT

    [ https://issues.apache.org/jira/browse/HBASE-9488?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13762842#comment-13762842
] 

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

bq.I didn't get how you reduce RPCs to one (is it implemented in this patch?).
Yes, See the ClientSmallScanner in the patch.

With the patch, no RPC when calling HTable#getScanner and ResultScanner#close, only call RPC
when calling ResultScanner#next
                
> 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-trunk.patch, HBASE-9488-trunkV2.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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