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Message Posted: Mon, 22 Feb 2010 @ 14:59:35 GMT

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Subj:   Re: Avoiding an all-row scan
From:   Dieter Noeth

mjrodriguezp wrote:

  - The table BDD_TABLAS.FIN_BORRAR_1 has only one row with the date I want to use SELECT * FROM BDD_TABLAS.FIN_BORRAR_1;  

Statistics on FIN_BORRAR_1.fec_vigencia, so the optimizer knows about that single row? If not it will estimate the number of rows equal to the number of AMPs in your system.

Statistics on PCL_HIS_CONTRATOS: fec_vigencia/PARTITION?

Is that all-row-scan really a full-table-scan or "enhanced by dynamic partition elimination"?

  The thing is than I need to have the date in a field of a table like this because it can change.  

  Is there a way to optimize the second or third query using the table FIN_BORRAR_1?  

If that table is always a single row you might try a view:

     SELECT DATE '2009-12-31' AS fec_vigencia;

In TD12 the optimizer will completely remove the view-access and create exactly the same plan as the first query.

Btw, don't write dates using the old integer format anymore, better use "DATE '2010-02-22'"


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