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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-3623) Hive query hangs with limit 0 clause
Date Thu, 08 Oct 2015 22:56:27 GMT

    [ https://issues.apache.org/jira/browse/DRILL-3623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14949565#comment-14949565
] 

ASF GitHub Bot commented on DRILL-3623:
---------------------------------------

GitHub user sudheeshkatkam opened a pull request:

    https://github.com/apache/drill/pull/193

    DRILL-3623: Use shorter query path for LIMIT 0 queries on schema-ed tables

    Initial patch.
    
    DrillTable#providesDeferredSchema function is used by the NonDeferredSchemaTableLimit0Visitor
to check if the table can provide schema directly, and if so the result is directly returned.
    
    It seems the shorter query path for this query needs a hacky "otherPlan" in the DefaultSqlHandler
without major refactoring (Should I go ahead and make changes?). This also means that "EXPLAIN
PLAN ..." returns a plan that is different the actual query plan (without a check in ExplainHandler,
another hack).
    
    I think the classes need more meaningful names (NonDeferredSchemaTableLimit0Visitor).
    
    Also, note the type conversion using CALCITE_TO_DRILL_TYPE_MAPPING.

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/sudheeshkatkam/drill DRILL-3623

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

    https://github.com/apache/drill/pull/193.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 #193
    
----
commit a766c54b34697df8b851204705ea1ce16c7114b7
Author: Sudheesh Katkam <skatkam@maprtech.com>
Date:   2015-10-08T22:38:00Z

    DRILL-3623: Use shorter query path for LIMIT 0 queries on schema-ed tables

----


> Hive query hangs with limit 0 clause
> ------------------------------------
>
>                 Key: DRILL-3623
>                 URL: https://issues.apache.org/jira/browse/DRILL-3623
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Storage - Hive
>    Affects Versions: 1.1.0
>         Environment: MapR cluster
>            Reporter: Andries Engelbrecht
>             Fix For: Future
>
>
> Running a select * from hive.table limit 0 does not return (hangs).
> Select * from hive.table limit 1 works fine
> Hive table is about 6GB with 330 files with parquet using snappy compression.
> Data types are int, bigint, string and double.
> Querying directory with parquet files through the DFS plugin works fine
> select * from dfs.root.`/user/hive/warehouse/database/table` limit 0;



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