[jira] [Assigned] (HIVE-3733) Improve Hive's logic for conditional merge

["Zhenxiao Luo (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-3733?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Zhenxiao Luo reassigned HIVE-3733:
----------------------------------

    Assignee: Zhenxiao Luo  (was: Pradeep Kamath)
    
> Improve Hive's logic for conditional merge
> ------------------------------------------
>
>                 Key: HIVE-3733
>                 URL: https://issues.apache.org/jira/browse/HIVE-3733
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: Pradeep Kamath
>            Assignee: Zhenxiao Luo
>         Attachments: HIVE-3733.1.patch.txt, HIVE-3733.3.patch.txt, HIVE-3733.4.patch.txt, HIVE-3733.5.patch.txt, HIVE-3733.optimizer.patch.txt
>
>
> If the config hive.merge.mapfiles is set to true and hive.merge.mapredfiles is set to false then when hive encounters a FileSinkOperator when generating map reduce tasks, it will look at the entire job to see if it has a reducer, if it does it will not merge. Instead it should be check if the FileSinkOperator is a child of the reducer. This means that outputs generated in the mapper will be merged, and outputs generated in the reducer will not be, the intended effect of setting those configs.
> Simple repro:
> set hive.merge.mapfiles=true;
> set hive.merge.mapredfiles=false;
> EXPLAIN
> FROM <input_table>
> INSERT OVERWRITE TABLE <output_table1> SELECT key, COUNT(*) group by key
> INSERT OVERWRITE TABLE <output_table2> SELECT *;
> The output should contain a Conditional Operator, Mapred Stages, and Move tasks

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