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From "Zheng Shao (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HIVE-655) Add support for user defined table generating functions
Date Sun, 15 Nov 2009 23:53:48 GMT

    [ 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:
---------------------------------

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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