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https://issues.apache.org/jira/browse/HIVE-655?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12778196#action_12778196
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Zheng Shao commented on HIVE-655:
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Yeah I think we can support both formats. I agree "LATERAL VIEW" is a better
and more consistent with SQL, but that might require much more time to
implement (given that the discussion of this issue was started long time ago
and Paul has done most of the work given the current design).
We can finish the current implementation asap, and at the same time keep in
mind about the "LATERAL VIEW" struct, and implement it when we get time.
Does "LATERAL VIEW" supports exploding multiple columns (as a cartisian
product)?
@Raghu: The history of map/reduce and transform was like this: tranform was in
the first proposal and implemented when hive was started. Later we added "Map"
and "Reduce" as a shortcut so that users (who know map-reduce already) can
understand it better. However, there are also concerns from users (e.g. Venky)
because the keywords do not make sure the "map" and "reduce" are run in actual
"map" and "reduce" phase. So I would say these are historical issues.
> Add support for user defined table generating functions
> -------------------------------------------------------
>
> Key: HIVE-655
> URL: https://issues.apache.org/jira/browse/HIVE-655
> Project: Hadoop Hive
> Issue Type: New Feature
> Components: Query Processor
> Reporter: Raghotham Murthy
> Assignee: Paul Yang
> Attachments: HIVE-655.1.patch, HIVE-655.2.patch
>
>
> Provide a way for users to add a table generating function, i.e., functions
> that generate multiple rows from a single input row. Currently, the only way
> to do it is via the TRANSFORM clause which requires streaming the data.
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