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Date: Mon, 11 Feb 2013 02:17:12 +0000 (UTC)
From: "James Taylor (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
Message-ID: <JIRA.12631632.1360484849257.271676.1360549032909@arcas>
In-Reply-To: <JIRA.12631632.1360484849257@arcas>
References: <JIRA.12631632.1360484849257@arcas>
Subject: [jira] [Commented] (HBASE-7805) Scan of same region processed
 serially if table has region observer coprocessor
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    [ https://issues.apache.org/jira/browse/HBASE-7805?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13575597#comment-13575597 ] 

James Taylor commented on HBASE-7805:
-------------------------------------

The coprocessor time will be much faster - they're running the scan completely on the server side and only returning a single row back to the client (mimicing what Phoenix does for an ungrouped aggregate query). Still not using the enhancements that Lars added, so the number will get better after that. 

The 0.94.2 numbers are fine, but my coprocessor wasn't being used for the 0.94.5 run. The jar path needs to be specified as null or else the coprocessor is silently ignored. The updated number are below (nice improvement on the non coprocessor case for 0.94.5):

10,000,000 rows
===============
v 0.94.2 (@1395367)
-------------------
With coprocessors
Serial time: 5352, Parallel time: 3548 (66%)
Without coprocessors
Serial time: 13442, Parallel time: 7456 (55%)

v 0.94.5 (latest)
-----------------
With coprocessors
Serial time: 5089, Parallel time: 3604 (71%)
Without coprocessors
Serial time: 9711, Parallel time: 6226 (64%)
                
> Scan of same region processed serially if table has region observer coprocessor
> -------------------------------------------------------------------------------
>
>                 Key: HBASE-7805
>                 URL: https://issues.apache.org/jira/browse/HBASE-7805
>             Project: HBase
>          Issue Type: Bug
>          Components: Coprocessors, Scanners
>    Affects Versions: 0.94.4
>            Reporter: James Taylor
>            Priority: Minor
>             Fix For: 0.96.0, 0.94.6
>
>         Attachments: 7805-0.94.patch, 7805-trunk.txt, 7805-trunk-v2.txt, ParallelScanTestCoProc.java, ParallelScanTest.java
>
>
> If multiple scans to different parts of the same region are executed in parallel, they are processed serially if the table has a region observer coprocessor.

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