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Message Posted: Tue, 28 Aug 2007 @ 09:24:51 GMT


     
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Subj:   Re: Adding new columns to an 11 billion row table
 
From:   Christian Schiefer, makeITdone

Hi,

have a look in the "Database Design" and look for the "Base Table Row Format" section in the TD documentation.

If one of the column types is VARCHAR, forget it ....

If not:

If you add 1 column with the compress option ( just compress the default value ) it costs you just 1 BIT in the row header. You plan to add 3 columns, it works out to 3 additional BITS.

Depending on your current table layout, the performance heavily depends on if you can fit your additional 3 BITS into an already partly used BYTE from the table header.

If the additional 3 BITS do not ride over a BYTE boundary, then the performance should be reasonable, because just the row headers have to be updated.

If they don't fit, invest some time for a nice coffee.

Coming back from the theory:

The amount of NUSIs and the PARTITION should not harm the all over process.

Just make a test with a smaller sample of the table. E.g. 1 percent (110 million rows) and expect additional linear time consumption for your full table.


BR

Christian



     
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