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Message Posted: Thu, 03 May 2012 @ 10:18:25 GMT


     
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Subj:   Redistribution when doing RANK() OVER on PI
 
From:   Anomy Anom

<-- Anonymously Posted: Wednesday, May 02, 2012 09:17 -->

I was wondering why the following SELECT SQL will cause redistribution on the all-AMPs STAT FUNCTION Step?

I'm using the Primary Index (only) in the OLAP function, so all the data needed to to the ranking is already present on any given Amp (BTW - when I remove the OLAP function from the Query, the redistribution goes away).

     SELECT
          RANK() OVER ( PARTITION BY PI_Column ORDER BY PI_Column )
         ,PI_Column
         ,ColumnA
         ,ColumnB
     FROM
          MyTable;

(There is a NUPI on PI_Column on MyTable)


Thanks!



     
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