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From "Paul Yang (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HIVE-935) support LATERAL VIEW
Date Wed, 02 Dec 2009 02:48:20 GMT

    [ https://issues.apache.org/jira/browse/HIVE-935?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12784597#action_12784597
] 

Paul Yang commented on HIVE-935:
--------------------------------

I recall in our  meeting yesterday that having a GenericUDTF.forward() was considered preferable
to having GenericUDTF.process() return an array of results because there were performance
benefits. Namely, the GenericUDTF could create a mutable object once, and then call GenericUDTF.forward()
multiple times on the same object.

However, the following LateralViewJoinOperator will need to hold all the objects forwarded
by the GenericUDTF for  a given row before it can run the crossproduct/join  - which implies
that the forwarded objects can't be the same.

Are there other reasons for having a separate GenericUDTF.forward()?

> support LATERAL VIEW
> --------------------
>
>                 Key: HIVE-935
>                 URL: https://issues.apache.org/jira/browse/HIVE-935
>             Project: Hadoop Hive
>          Issue Type: New Feature
>          Components: Query Processor
>            Reporter: Namit Jain
>            Assignee: Paul Yang
>
> For table functions, the following syntax should be supported
> select ... from T LATERAL VIEW explode(adid_list) as adid,...

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