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From Andrus Adamchik <and...@objectstyle.org>
Subject Re: On the fly reengineering of database schema
Date Fri, 20 Jul 2007 18:51:21 GMT
> Is there any reason, in principle, why we couldn't read that info
> during startup of the application? IOW, reengineering on the fly.

No reason - you can totally do it. Cayenne runtime mapping is  
completely dynamic. It's not like we would need to re-enhance Java  
bytecode or anything :-)

Andrus


On Jul 20, 2007, at 9:42 PM, Øyvind Harboe wrote:

> Currently our Cayenne app has the database field size and types stored
> in the configuration files that ship with the application. They were
> generated in the Cayenne modeler.
>
> Is there any reason, in principle, why we couldn't read that info
> during startup of the application? IOW, reengineering on the fly.
>
> - It would allow database maintainers to adjust field sizes without us
> updating Cayenne.
> We have a lot of variants of the database schema in the field and
> changing size of a  NVARCHAR or changing an NVARCHAR to a CLOB would
> be typical operations.
> - Adding a field to a database table could be done from the  
> database GUI
> - We would be able to cope easily with the absence or presence of
> optional table fields
>
> The Cayenne modeler would still be useful to choose Java
> representation of the fields regardless of their type(CLOB, NVARCHAR,
> CHAR, etc.).
>
> We have some database adapters that don't do robust reengineering
> (FoxBase, MS Access, shudder!), but presumably we could
> programatically adapt the Cayenne database schema for those/stick with
> a default one which we do today.
>
> -- 
> Øyvind Harboe
> http://www.zylin.com - eCos ARM & FPGA  developer kit
>


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