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Posted to dev@hive.apache.org by bharath vissapragada <bh...@gmail.com> on 2011/04/13 15:25:49 UTC

Virtual Columns - help

Hi all,

What is the use of the class "VirtualColumn" ? Why are  they are always
pushed into the the RowResolver to create a TableScanDesc ?

Any help is highly appreciated !

-- 
Regards,
Bharath .V
w:http://research.iiit.ac.in/~bharath.v

Re: Virtual Columns - help

Posted by yongqiang he <he...@gmail.com>.

Virtual Columns  is now mainly used for IO information, like file
name, block offset.

The reason of pushing to RowResolver is to be able to select on these columns.

On Wed, Apr 13, 2011 at 6:25 AM, bharath vissapragada
<bh...@gmail.com> wrote:
> Hi all,
>
> What is the use of the class "VirtualColumn" ? Why are  they are always
> pushed into the the RowResolver to create a TableScanDesc ?
>
> Any help is highly appreciated !
>
> --
> Regards,
> Bharath .V
> w:http://research.iiit.ac.in/~bharath.v
>