[jira] [Commented] (DRILL-6574) Add option to push LIMIT(0) on top of SCAN (late limit 0 optimization)

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DRILL-6574?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16547687#comment-16547687 ] 

ASF GitHub Bot commented on DRILL-6574:
---------------------------------------

KazydubB opened a new pull request #1386: DRILL-6574: Add option to push LIMIT(0) on top of SCAN (late limit 0 optimization)
URL: https://github.com/apache/drill/pull/1386
 
 
   

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> Add option to push LIMIT(0) on top of SCAN (late limit 0 optimization)
> ----------------------------------------------------------------------
>
>                 Key: DRILL-6574
>                 URL: https://issues.apache.org/jira/browse/DRILL-6574
>             Project: Apache Drill
>          Issue Type: Improvement
>    Affects Versions: 1.13.0
>            Reporter: Bohdan Kazydub
>            Assignee: Bohdan Kazydub
>            Priority: Major
>              Labels: doc-impacting
>
> Currently we have early limit 0 optimization (planner.enable_limit0_optimization) which determines query data types before actual scan. Since we not always able to determine data type during planning, we need to add one more option to enable late limit 0 optimization (planner.enable_limit0_on_scan, exit query right after scan. LIMIT(0) on SCAN for UNION and complex functions will be disabled i.e. UNION and complex functions need data to produce result schema. This would not work for the following list of functions: KVGEN, MAPPIFY, FLATTEN, CONVERT_FROMJSON, CONVERT_TOJSON, CONVERT_TOSIMPLEJSON, CONVERT_TOEXTENDEDJSON.
> Query plan examples:
>  // todo add two plans before and after the changes
> Also both early and late limit 0 optimization will be turned on by default.



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