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From "Malcolm Edgar" <malcolm.ed...@gmail.com>
Subject Re: best practice for handling database schema changes
Date Sun, 03 Dec 2006 22:49:39 GMT
I have also used a very similar approach on another project.  We used
Java commands to perform each version update, the advantage of this
over straight SQL files is that you can migrated data using Java logic
into the new schema.

regards Malcolm

On 12/4/06, Aristedes Maniatis <ari@ish.com.au> wrote:
> Interesting article. We implemented something similar, but without
> hard coding the SQL to update the schema into Java. Instead we have a
> folder full of files named 1.sql, 2.sql, etc. Each one contains the
> SQL required to update the database schema. Every time the server
> application runs it reads a special table in the database with one
> column and one record. That value is the 'schema version' from the
> last launch of the application. If this number is lower that the
> largest xx.sql file in the folder, then that sql file is executed and
> the version updated.
>
> We do all this before Cayenne is intialised in any way in our
> application.
>
> The only thing we haven't yet done is to write a junit test that
> validates the sum total of all our incremental updates is the same as
> a single SQL export from the current Cayenne model.
>
> Ari Maniatis
>
>
> On 02/12/2006, at 12:56 AM, Michael Gentry wrote:
>
> > I found this yesterday (although I haven't read it all yet):
> >
> > http://www.stepwise.com/Articles/2005/DBChanges/index.html
> >
> > Not sure if it'll be helpful, but it looks similar to some ideas I had
> > been pondering in the past.
> >
> > /dev/mrg
> >
> >
> > On 11/30/06, Michael Gentry <blacknext@gmail.com> wrote:
> >> Currently you have to manually merge the changes just as you states.
> >> I should probably make an FAQ for this ...
> >>
> >> Thanks,
> >>
> >> /dev/mrg
> >>
> >>
> >> On 11/30/06, Tobias SCHOESSLER <Tobias.Schoessler@unvienna.org>
> >> wrote:
> >> >
> >> > hi,
> >> > What is the best practice for handling changes to the database
> >> schema once a
> >> > cayenne mapping was created?
> >> > We use the 'reverse engineer from database' feature to create an
> >> initial
> >> > mapping. But then we usually have to do manual changes like map
> >> some pks,
> >> > add flattened relationships, etc.
> >> > If then the database schema needs to be changed we usually have
> >> a problem as
> >> > 'reverse engineer from database' overwrites everything. There
> >> seems to be
> >> > the possibility to replace only selected tables but if you do
> >> this the
> >> > relationships are messed up. Is there a way to  merge the
> >> changes with the
> >> > current model/mapping?
> >> >
> >> > thanks
> >> >
> >> > Tobias
> >>
>
>
>
>
>
> -------------------------->
> ish
> http://www.ish.com.au
> Level 1, 30 Wilson Street Newtown 2042 Australia
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