[jira] Commented: (HIVE-51) Generate and accept JSON as the input-output format from mappers and reducers

["Zheng Shao (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-51?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12799440#action_12799440 ] 

Zheng Shao commented on HIVE-51:
--------------------------------

With HIVE-785, we should use RecordReader and RecordWriter together with the JSONSerDe for transforms.

> Generate and accept JSON as the input-output format from mappers and reducers
> -----------------------------------------------------------------------------
>
>                 Key: HIVE-51
>                 URL: https://issues.apache.org/jira/browse/HIVE-51
>             Project: Hadoop Hive
>          Issue Type: Bug
>          Components: Query Processor
>            Reporter: Venky Iyer
>
> set mapred.data.format=JSON;
> ....
> MAP USING 'python filter.py'
> ....;
> would mean that filter.py would receive a JSON formatted dictionary of the columns instead of a tab-delimited string.
> { column1: value1, column2: [1,2,3] } etc
> It would in turn produce JSON.
> This should be done so that the JSON is not transmitted back and forth over the network; it would be generated on the fly on the mapper node, and converted back to the standard format used (tab-delimited, I assume).
> This seems like the simplest way for encoding type information in the input to mappers; it would also remove the need for silly boilerplate code that took a list of expected input column names, took the input stream, split it up, and made a dictionary of {column name: value} on every record.
> Output schemas (USING '' AS ...) might also be redundant with this in place, but I'm not sure if that is doable.

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