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From Bryan Pendleton <bpendle...@amberpoint.com>
Subject Re: pagesize for a given table
Date Tue, 02 Feb 2010 14:49:31 GMT
Hi David,

> At what point does derby decide on the pagesize when it is creating a table?

During the bind processing (compilation) of the CREATE TABLE statement itself.

> I have a table with several varchar(4000) fields in it. Though they are 
 > varchar, does derby calculate row size based on the maximum possible column
 > size for variable sized columns in deciding whether to bump up the pagesize to 32K?

Yes, Derby bases its calculation on the max column size for VARCHAR, so 4000
in your case.

I'm a little surprised that the too-large pagesize would adversely affect
your performance, but you should be able to test it yourself by setting
the derby.storage.pageSize property, as Derby will obey that property even
if you have multiple long VARCHAR columns in your table.

thanks,

bryan



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