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https://issues.apache.org/jira/browse/DRILL-5065?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15703289#comment-15703289
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ASF GitHub Bot commented on DRILL-5065:
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GitHub user spanchamiamapr opened a pull request:
https://github.com/apache/drill/pull/670
DRILL-5065 - Optimize count( * ) queries on MapR-DB JSON Tables
In MapR-DB v5.2.0, we enabled '_id' only projection for JSON tables.
Hence, we can now optimize the following queries:
a. count(*) by projecting only the '_id' column.
b. '_id' only projections, including count(_id)
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/spanchamiamapr/drill master
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/drill/pull/670.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 #670
----
commit 3d12a9526365bcc96c605fc30f3b6fbe4961b97d
Author: Smidth Panchamia <spancha...@mapr.com>
Date: 2016-11-28T21:59:34Z
DRILL-5065 - Optimize count( * ) queries on MapR-DB JSON Tables
In MapR-DB v5.2.0, we enabled '_id' only projection for JSON tables.
Hence, we can now optimize the following queries:
a. count(*) by projecting only the '_id' column.
b. '_id' only projections, including count(_id)
----
> Optimize count( *) queries on MapR-DB JSON Tables
> -------------------------------------------------
>
> Key: DRILL-5065
> URL: https://issues.apache.org/jira/browse/DRILL-5065
> Project: Apache Drill
> Issue Type: Improvement
> Components: Storage - MapRDB
> Affects Versions: 1.9.0
> Environment: Clusters with MapR v5.2.0 and above
> Reporter: Abhishek Girish
> Assignee: Smidth Panchamia
>
> The JSON FileReader optimizes count(* ) queries, by only counting the number
> of records in the files and discarding the data. This makes the query
> execution faster & efficient.
> We need a similar feature in the MapR format plugin (maprdb) to optimize _id
> only projection & count(* ) queries on MapR-DB JSON Tables.
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