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From Stanley Bradbury <Stan.Bradb...@gmail.com>
Subject Re: Performance affected by adding a column?
Date Sat, 15 Dec 2007 00:58:39 GMT
Christian Rørdam wrote:
> We have a Derby database version of size about 1.5 GB. Some 
> people here say they have noticed a performance degradation after 
> adding a new column to an existing table. The table has about 12 000 
> rows.
> Is it normal that performance will degrade after adding a new column? 
> And if so, is there something special one should do when adding columns?
> Christian Rørdam
> Schlumberger OFS - IT Business Systems
Hi Christian -

My guess is the slowness has to do with space allocation in the 
datapages of the existing records that were created before the column 
was added.  Populating the column could cause many pagesplits.  You can 
use COMPRESS_TABLE to rebuild the table, reload the pages and 
re-establish free space in the datapages - my guess is it will help.

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