Re: On the fly reengineering of database schema

From: Andrus Adamchik (andru..bjectstyle.org)
Date: Fri Jul 20 2007 - 14:51:21 EDT

  • Next message: Øyvind Harboe: "Re: On the fly reengineering of database schema"

    > 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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