GitHub user ravipesala opened a pull request:
https://github.com/apache/incubator-carbondata/pull/359 [CARBONDATA-456] Fixing select count(*) slow issue
In the current master select count(*) query is slower because it try to retrieve all columns out of store and count it. But it is not needed using metadata could count the number of rows. So in driver side we no need to add all columns when projection is null, just don't add any columns and execute to return the empty rows but count could be calculated from those empty rows.
You can merge this pull request into a Git repository by running:
$ git pull
https://github.com/ravipesala/incubator-carbondata countstarslowissue
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/incubator-carbondata/pull/359.patchTo close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #359
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commit 2c74ef50cee15cae086d5ba2995eabebc262e570
Author: ravipesala <
[hidden email]>
Date: 2016-11-28T07:09:51Z
Fixing count(*) slow issue
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