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From "Prasanth Jayachandran (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-14310) ORC schema evolution should not completely disable PPD
Date Wed, 27 Jul 2016 21:46:20 GMT

    [ https://issues.apache.org/jira/browse/HIVE-14310?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15396456#comment-15396456
] 

Prasanth Jayachandran commented on HIVE-14310:
----------------------------------------------

rbt post and updating patch with base diff worked. Thanks for the tip!

> ORC schema evolution should not completely disable PPD
> ------------------------------------------------------
>
>                 Key: HIVE-14310
>                 URL: https://issues.apache.org/jira/browse/HIVE-14310
>             Project: Hive
>          Issue Type: Bug
>    Affects Versions: 2.2.0
>            Reporter: Prasanth Jayachandran
>            Assignee: Prasanth Jayachandran
>            Priority: Critical
>         Attachments: HIVE-14310.1.patch, HIVE-14310.2.patch, HIVE-14310.WIP.patch
>
>
> Follow up for HIVE-14214 which completely shuts off PPD when there is any schema evolution.
Some evolutions are safer for PPD like
> byte -> short -> int -> long
> -float -> double- (This is unsafe, see comments in SchemaEvolution.java in the patch)
> varchar <-> string (string to char, varchar to char and vice versa is also unsafe
conversion as Orc stores internal index with padded spaces for char)
> For all other conversions we can disable PPD for that specific column that has evolved
by returning TruthValue.YES_NO



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