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Message Posted: Tue, 06 Nov 2012 @ 22:24:18 GMT


     
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Subj:   Adding Compression - Redistributing data
 
From:   Anomy Anom

< -- Anonymously Posted: Tuesday, November 06, 2012 16:26 -- >

I am adding compression to the table and was surprised to looking at the explain plan. It says the data is being redistributed. Everything is same in both the tables except that the second table is having compression. Any idea why?

     Insert into test1.STAGE_TBL
     Sel * from test.STAGE_TBL;

     First, lock test1.CHAR(34)pseudo tableCHAR(34) for write on a row hash.

     Next, we lock test.CHAR(34)pseudo tableCHAR(34) for read on a row hash.

     We lock test1.STAGE_TBL for write and we lock test.STAGE_TBL for read.

     We do an All-AMPs RETRIEVE step from test.STAGE_TBL by way of an all-rows
     scan into Spool 8211, which is redistributed by hash code to all AMPs.

     We do a MERGE into table STAGE_TBL from Spool 8211.

     We Spoil the parser's dictionary cache for the table.

     We send out an END TRANSACTION step to all AMPs involved in processing the
     request.

Thanks.



     
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