[jira] [Updated] (PIG-4885) Turn off union optimizer if there is PARALLEL clause in union in Tez

["Rohini Palaniswamy (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/PIG-4885?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Rohini Palaniswamy updated PIG-4885:
------------------------------------
    Status: Patch Available  (was: Open)

> Turn off union optimizer if there is PARALLEL clause in union in Tez
> --------------------------------------------------------------------
>
>                 Key: PIG-4885
>                 URL: https://issues.apache.org/jira/browse/PIG-4885
>             Project: Pig
>          Issue Type: Improvement
>            Reporter: Rohini Palaniswamy
>            Assignee: Rohini Palaniswamy
>             Fix For: 0.16.0
>
>         Attachments: PIG-4885-1.patch
>
>
> In mapreduce, if PARALLEL clause was specified on UNION it was ignored as it was a map operation and split size was used. In Tez, when union optimizer is turned off it is a reduce side operation and we should let user control parallelism instead of relying on just auto-parallelism. This is specifically useful when user needs to control the number of output files.
> data = UNION A, B, C, D, E, F, G, H, I, J;
> store data;
> In the above case instead of manually controlling parallelism of A to J aliases to achieve desired parallelism the UNION clause can specify the desired parallelism using PARALLEL. i.e
> data = UNION A, B, C, D, E, F, G, H, I, J PARALLEL 50;
> This only works today if we set pig.tez.opt.union=false. We should automatically and selectively turn off union optimization for those unions that have PARALLEL clause.



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