[hibernate-dev] DB2 cross joins

[Gail Badner]

In the short term (for master), I'll add new DB2 dialect.

Thanks,
Gail

On Thu, Feb 16, 2017 at 7:45 AM, Steve Ebersole <steve at hibernate.org> wrote:

> To Gail's specific question... As Sanne stated, a new Dialect is the only
> option IMO for the moment.
>
> But what Chris brings up is important, and something we really should start
> deciding.  We have been discussing it off and on for 4-5 years.
>
> Dialects were originally designed to be inflexible.  We can debate the
> merits of that decision, but it is what leads to the need for all these
> Dialect impls for seemingly trivial deviations.  So there is also a long
> term discussion to be had here.
>
> However, it is not quite as cut-and-dried as you make out Sanne.  Quite a
> few Dialects already "configure themselves" based on various things (e.g.
> take a look at the H2Dialect's ctor).  The problem is that to-date there
> has not been a standard way to do that, especially in regards to gaining
> access to JDBC metadata as part of that self-config.  The ideal solution
> would be to keep Dialects static/inflexible but to use that along with JDBC
> metadata to build a true understanding of how to interact with the
> database.
>
> Personally, I think it is easier to just simply let the Dialect configure
> itself.  But there is a certain danger there, as there always is when
> completely changing the design of something, especially something that many
> many users use.  We shall see that play out soon with Type :)
>
> On Thu, Feb 16, 2017 at 8:54 AM Sanne Grinovero <sanne at hibernate.org>
> wrote:
>
> > On 16 February 2017 at 14:23, Chris Cranford <crancran at gmail.com> wrote:
> > > We have actually discussed doing something where Dialect's
> auto-configure
> > > themselves, but such a change would likely be appropriate for a major
> > > release only.
> > >
> > > On 02/16/2017 04:57 AM, Christian Beikov wrote:
> > >> How about a different approach? Like passing the DB version somehow to
> > >> the dialect so that it can decide for itself instead of having
> different
> > >> subclasses.
> >
> > People currently expect to be able to configure a Dialect by choosing
> > a specific classname.
> >
> > I don't disagree on exploring evolutions, but indeed I'd not change
> > such matters in a minor release;
> >
> > Gail needs a fix focusing on the cross join issue so a new class will
> > suffice for the immediate need.
> >
> > >>
> > >> Am 16.02.2017 um 08:16 schrieb Gail Badner:
> > >>> HHH-11487 can be fixed by using changing
> > DB2Dialect#getCrossJoinSeparator
> > >>> to return " cross join ".
> > >>>
> > >>> DB2 9.1 did not support CROSS JOIN, but DB2 9.5 and later do support
> > CROSS
> > >>> JOIN. I see that DB2 9.1 is no longer supported as of April 30, 2015.
> > >>>
> > >>> It's tempting to just update DB2Dialect, but I suspect that would
> break
> > >>> existing applications still using DB2 9.1.
> > >>>
> > >>> I'm considering adding a new dialect DB295Dialect that extends
> > DB2Dialect
> > >>> and overrides DB2Dialect#getCrossJoinSeparator to return "cross
> join".
> > >>>
> > >>> WDYT?
> >
> > +1
> >
> > Thanks,
> > Sanne
> >
> >
> > >>>
> > >>> Regards,
> > >>> Gail
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