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From Bryan Pendleton <bpendle...@amberpoint.com>
Subject Re: Derby minimum size tweaking: how far can I go?
Date Tue, 27 Mar 2007 15:27:53 GMT
> Is there a way to reduce this number, by storing several/all tables into 
> one 'data' file?

You could accomplish this in your application, by defining a single
table with a very general physical schema, then using view definitions
and careful application coding to store logically distinct records into
the same physical table.

E.g., suppose you have two data types:
  - EMPLOYEE (E_ID, E_NAME, E_SSN, E_DEPT_ID)
  - DEPARTMENT (D_ID, D_NAME, D_MGR_ID)

Define a single table with the schema:
   (ROW_TYPE, ID, NAME, E_SSN, E_DEPT_ID, D_MGR_ID)

Then define two VIEWs:
  - EMP_VIEW as select ID as E_ID, NAME as E_NAME, E_SSN, E_DEPT_ID
    where ROW_TYPE = 1
  - DEPT_VIEW as select ID AS D_ID, NAME as D_NAME, D_MGR_ID
    where ROW_TYPE = 2

And to store employee records, insert the correct set of columns
and make sure that you set ROW_TYPE to 1, while for department
records, insert the correct set of columns and make sure that
you set ROW_TYPE to 2.

thanks,

bryan



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