[hibernate-dev] SchemaManagementTool changes for 5.1 (was Re: 5.1 tentative release date)

Thu Jan 28 13:27:19 EST 2016

For this to work will require some significant changes.  The main one being
to combine JPA's support for schema generation along
with SchemaManagementTool.  The reason being simply that I will need to
encapsulate the interpretation of all these settings behind
the SchemaManagementTool facade in order for things to properly
replace SchemaManagementTool as Gunnar suggests.

I am starting this work now on top of the work Gunnar has already done on
the PR he sent[1].  But that work is just the tip of the iceberg.  So if
you have input to this, speak soon.

[1] https://github.com/hibernate/hibernate-orm/pull/1231

On Wed, Jan 20, 2016 at 6:13 AM Gunnar Morling <gunnar at hibernate.org> wrote:

> I went for the proposed intermediary step to avoid breaking the API of
> SchemaManagementTool and its delegates. If you have a way for not
> breaking the API or think breaking it is alright, then +1 for doing
> the ProperSolution™ in 5.1.
>
> What would it comprise, changing the delegate methods such as
> doCreate() to expect a single parameter object providing all the
> required info? Target could be a part of this, just an enum probably,
> based on wich delegates would do their thing. If it's that, I can try
> and help out with it.
>
> Regarding the release schedule, I'd personally be fine with pushing it
> a bit back, but then I don't know whether there are any other hard
> timelines to be met.
>
>
> 2016-01-19 16:25 GMT+01:00 Steve Ebersole <steve at hibernate.org>:
> > I'd like to get this work into 5.1.  But, as much as possible, I'd like
> to
> > get the ProperSolution in place rather than just a
> StepInTheRightDirection.
> > If we need to push this date 2-4 weeks I am ok with that.  That would
> help
> > us coordinate with Infinispan 8.2 schedule (iiuc) for
> hibernate-infinispan,
> > not to mention I still have to review the work Vlad has done on the docs
> > again as well as polish the load-by-multi-id API[1].
> >
> > [1] Sanne still waiting on your feedback to the open question of internal
> > routing of those calls.
> >
> > On Tue, Jan 19, 2016 at 8:41 AM Gunnar Morling <gunnar at hibernate.org>
> wrote:
> >>
> >> Hi Steve,
> >>
> >> As discussed on IRC, I tried plugging in my own SchemaManagementTool
> >> and delegates and letting them do the initialization work required for
> >> OGM.
> >>
> >> I am hitting a wall though when it comes to the usage in the
> >> SchemaExport controller: As it's invoking doCreate() and doDrop()
> >> right in the constructor with a "fake" target for delegating the SQL
> >> statements, I am bitten by the fact that SchemaExport is instantiated
> >> twice in SessionFactoryImpl (once for create, once for drop at
> >> shutdown), so I see to invocations to doCreate() and doDrop(). Also I
> >> am lacking the knowledge of what's passed as Target for the controller
> >> invocation.
> >>
> >> So I went ahead and changed SchemaExport to invoke SchemaCreator and
> >> -Dropper only in execute(), passing them actual Target implementations
> >> as it's done in SchemaUpdate, too. It's not yet what you described as
> >> the ultimate goal (not looping back to Target), but IMO it's a step
> >> into the right direction, not the least making things consistent
> >> between SchemaExport and SchemaUpdate and also leaving APIs largely
> >> unchanged for the time being. With that I should be able to do it on
> >> the OGM side as you suggested, essentially ignoring the
> >> Target/Exporter stuff.
> >>
> >> I've filed ORM PR https://github.com/hibernate/hibernate-orm/pull/1231
> >> for the change. Let me know what you think.
> >>
> >> Cheers,
> >>
> >> --Gunnar
> >>
> >>
> >> 2016-01-14 15:51 GMT+01:00 Steve Ebersole <steve at hibernate.org>:
> >> > I am not sure I am a big fan of The String->Object change
> specifically.
> >> > In
> >> > theory it sounds great.  But there is a major premise in schema
> tooling
> >> > around the idea of the actions being reduce-able to Strings.  That's
> >> > important not just for SQL, but for the idea of writing to a file as
> >> > well.
> >> > It also affects the whole concept of Exporter/Exportable.
> >> >
> >> > The ultimate design goal here is to unify schema creation and dropping
> >> > across native and JPA requirements.  I just simply have not had the
> time
> >> > to
> >> > work on that.  This would all happen "behind" SchemaManagementTool and
> >> > friends.  SchemaExport, etc are actually just controllers responsible
> >> > for
> >> > coordinating the calls into the SchemaManagementTool delegates.  The
> >> > main
> >> > problem at the moment IMO is that Target gets passed into these
> >> > SchemaManagementTool delegates.  Ideally, and certainly this would fit
> >> > with
> >> > your case, I think we want SchemaManagementTool or its delegates to
> >> > handle
> >> > interpreting the "arguments".  This was part of the intent of
> developing
> >> > the "CommandLineArgs" stuff that is used inside SchemaExport, etc now;
> >> > the
> >> > idea was to encapsulate the settings each tool needs to operate and
> >> > isolate
> >> > the process of building/interpreting those args.
> >> >
> >> > The next step I wanted to look at there was to morph CommandLineArgs
> >> > into a
> >> > more generic "parameter object" for initializing the actual
> >> > SchemaManagementTool delegates.
> >> >
> >> > The idea is that the more we can push into SchemaManagementTool and
> its
> >> > delegates the more pluggable this entire process becomes.  Ultimately,
> >> > as I
> >> > mentioned above, I just do not think it is feasible for ORM and OGM to
> >> > share all of these implementation contracts.  Forcing a switch from
> >> > String
> >> > (the DDL) arguments to some amorphic Object reinforces that in my
> mind.
> >> > But that would not stop OGM from completely swapping
> >> > SchemaManagementTool
> >> > and its delegates and simply not using Target, Exporters, etc.
> >> >
> >> >
> >> > On Thu, Jan 14, 2016 at 7:44 AM Gunnar Morling <gunnar at hibernate.org>
> >> > wrote:
> >> >
> >> >> Hi Steve,
> >> >>
> >> >> One thing useful to have for OGM would be a generalization of the
> >> >> hbm2ddl tooling so we can re-use it for managing NoSQL databases. Not
> >> >> all of them are "schemaless", e.g. Cassandra works with a fixed
> >> >> schema, and while MongoDB largely is schemaless, we still want to
> >> >> create stuff like indexes in the database.
> >> >>
> >> >> I took a look and found that SchemaManagementTool as a pluggable
> >> >> service already goes halfway into that direction. The issue with it
> is
> >> >> that I cannot replace the list of exporters used by SchemaExport nor
> >> >> the list of tool targets used by SchemaUpdate. Having a pluggable
> >> >> service allowing me to customize that with an OGM-specific
> >> >> implementation should do the trick.
> >> >>
> >> >> As per some comments in the code, SchemaExport seems to be in some
> >> >> intermediary state, where the ops are not executed directly through
> >> >> the targets passed to SchemaCreator/Dropper but are read into String
> >> >> arrays which are then passed on to separate exporters. I suppose part
> >> >> of that work should be to consolidate this and basically follow the
> >> >> same approach as used in SchemaUpdate?
> >> >>
> >> >> Another facet is that for some OGM grid dialects we'd need another
> >> >> representation of commands than Strings, as not all the backends have
> >> >> a DDL but expect API invocations for that purpose. For that it'd be
> >> >> required to change Target#accept(String) into accept(Object) so we
> can
> >> >> pass some kind of command object. File exports would only work in a
> >> >> limited fashion, but we could live with that. Schema
> creation/dropping
> >> >> bound to the SF lifecycle is what I am after here.
> >> >>
> >> >> I'd be willing to work on this once we agree on the general approach.
> >> >>
> >> >> Any thoughts?
> >> >>
> >> >> Thanks,
> >> >>
> >> >> --Gunnar
> >> >>
> >> >>
> >> >>
> >> >> 2016-01-13 14:10 GMT+01:00 Guillaume Smet <guillaume.smet at gmail.com
> >:
> >> >> > On Tue, Jan 12, 2016 at 6:40 PM, Steve Ebersole <
> steve at hibernate.org>
> >> >> wrote:
> >> >> >
> >> >> >> If you clean up the conflicts I can look for 5.1
> >> >> >>
> >> >> >
> >> >> > Done!
> >> >> >
> >> >> > --
> >> >> > Guillaume
> >> >> > _______________________________________________
> >> >> > hibernate-dev mailing list
> >> >> > hibernate-dev at lists.jboss.org
> >> >> > https://lists.jboss.org/mailman/listinfo/hibernate-dev
> >> >>
> >> > _______________________________________________
> >> > hibernate-dev mailing list
> >> > hibernate-dev at lists.jboss.org
> >> > https://lists.jboss.org/mailman/listinfo/hibernate-dev
>