[odb-users] Re: Handling the database versioning concern

[Michael Powell]

On Tue, May 21, 2013 at 7:20 AM, Michael Powell <mwpowellhtx at gmail.com> wrote:
> Hello,
>
> How does ODB handle the object and/or database versioning concern?
> Maybe a better question is, whether ODB does that? I'm sure the folks
> with C/S are well aware of this opportunity and the challenges
> involved.

I'll also mention, I don't think this concern is necessarily a
non-starter. Would be nice, but I believe there are ways to navigate
that issue cross platform. Like we could design a version sniffer and
expect end-users to run that C# .NET upgrader across platforms. Would
involve copying databases over SCP, upgrading them, then redeploying
them, type thing. Fairly doable in our set of tools for our purposes I
think.

> Hopefully when we design a database and an ORM the first time that's
> the only version we'll ever be concerned about. Sarcasm intentional.
> Obviously this is impractical to expect as new discoveries are made in
> the maturing of a given domain or model.
>
> One approach I've taken in the past, for example, with C# NHibernate
> and Fluent NHibernate, is to ensure that a set of ordered database
> updaters is run. Usually, in C# anyway, this ends up being composed
> and reflected out of a set of assemblies at run time. Updates only run
> when they need to, if, say, some version table reflects they need to,
> type thing.
>
> In C++-isms, that might be captured as a vector of these instances, or
> perhaps even a variadic template to capture the concern(s) more
> efficiently at compile time.
>
> I know Boris and folks dislike like the words framework or design
> pattern, also given that ODB supports several databases, does ODB
> provide any hooks in its object space to facilitate the versioning
> process? Even something like register these upgrade instances which
> consequently run embedded SQL statements to upgrade, type thing? Or
> perhaps more auto-magically generated than that?
>
> Thank you...
>
> Regards,
>
> Michael Powell