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https://issues.apache.org/jira/browse/HIVE-14310?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15396582#comment-15396582
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Owen O'Malley commented on HIVE-14310:
--------------------------------------

+1

> 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-14310.4.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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