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From: mayunSaicmotor <git@git.apache.org>
To: issues@carbondata.incubator.apache.org
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Subject: [GitHub] incubator-carbondata pull request #732: [CARBONDATA-754] improve performance...
Content-Type: text/plain
Message-Id: <20170405171906.6DB04DFC8E@git1-us-west.apache.org>
Date: Wed,  5 Apr 2017 17:19:06 +0000 (UTC)
archived-at: Wed, 05 Apr 2017 17:19:16 -0000

GitHub user mayunSaicmotor reopened a pull request:

    https://github.com/apache/incubator-carbondata/pull/732

    [CARBONDATA-754] improve performance when order by prefix columns of mdk  + limit

    the improvement scenario  is for  order by prefix columns of mdk  + limit
    
    1. order by prefix columns of mdk   asc + limit 
    2. order by prefix columns of mdk   desc + limit 
    3. order by prefix columns of mdk   asc + limit + filter
    4. order by prefix columns of mdk   desc + limit + filter
    
    the logical is to leverage  the mdk sort feature to get the sorted data. The performance is much better.
    for example,  order by prefix columns of mdk  + limit on 20,000,000 data, the  performance can be from  10s to about 1s.
    if do not want to use this feature, can also set    CarbonCommonConstants.ORDER_BY_MDK_OPTIMIZATION_FLG = false.
    
    
You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/mayunSaicmotor/incubator-carbondata orderby-mdk

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/incubator-carbondata/pull/732.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #732
    
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