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From Thomas Dudziak <tom...@gmail.com>
Subject Re: oracle database model dangerously broken
Date Mon, 06 Feb 2006 22:59:02 GMT
On 2/6/06, Craig L Russell <Craig.Russell@sun.com> wrote:

> Well, this describes my app and I guess I see it a bit differently.
> I'd like to use DdlUtils to capture any database schema recognizing
> that the full round trip development of schema is not supported.
> Really all I want here is accurate representation of the actual schema.
>
> It's still of great value to be able to point DdlUtils at a database
> and get its database-specific representation into a portable format
> and to be able to use this format to do such things as generation of
> POJO Java classes from the database. If we can't get the actual
> database representation, then it's of much less value for this
> application.

Mhmm, I'm sorry but I think I still don't really understand what
you're saying (just got back from the movies so I'm not fully here
yet).
Ain't database-specific representation and portability contradicting ?
Of course, I could try to read the exact schema using Oracle's sql
plus and encode that into an XML file. But what is the benefit ? I can
only use this with an Oracle database (and likely only with certain
versions) so it isn't portable.
On the other hand, having a portable version (e.g. in terms of JDBC)
looses detail that might or might not be important to the application.
This is why DdlUtils currently focuses on database creation. If the
developer has no problems defining the schema in terms of JDBC types
and constraints, then there are no database specific details to loose.

I can see the benefit of being able to read a schema from an existing
database and to transfer that to another database. But for databases
that contain database specifics, full detail preservation can IMO only
be achieved if the databases are the same and a database-specific
format is used (i.e. SQL something similar produced by a dump).
When transfering to a different database product, you're bound to
loose some detail. Of course, the shared feature set is likely larger
than what JDBC provides. And there certainly is room for improvement
in DdlUtils. E.g. it would be useful to have the ability to specify
sequences in an database-independent way.

regards,
Tom

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