There are currently a few open issues in schema generation that need
clarification. These pertain to sections 9.4 ("Schema generation")
and 8.2.1.9 ("properties") in the spec.
I've made some clarifications and proposed some additions to the
metadata for schema generation as described below. The draft I've
just uploaded reflects these changes (
http://java.net/projects/jpa-spec/downloads/download/JavaPersistence01282013.pdf).
Please review these sections and post any feedback. Changes are summarized below.
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Section 9.4
This section isn't sufficiently clear about requirements for the
specification of schema-generation-action and schema-generation-target.
I've clarified that schema-generation-action must be specified or no
actions will be taken. This was an assumed default in the current
public draft, but IMO not sufficiently explicit.
Given the clarification to schema-generation-action, I think it now
makes sense for schema-generation-target to have default values.
That is, if script targets are specified by the properties for scripts,
then generation actions should default into scripts. If not, actions
should be directly into the database.
The current public draft assumes that if script sources are specified,
generation should occur from scripts exclusively; and conversely, if
script sources are not specified, generation should occur exclusively
from the ORM metadata. I've gotten feedback that this wasn't sufficiently
flexible, and that we should support a combination of ORM and script
sources. (For example, consider the case where generation should occur
from scripts, but it is desirable to add stored procedures to the database.)
I therefore propose that we add a schema-generation-source property
that will support such combination. Again, if script sources are specified
by the properties for scripts, then generation will default to use of
only script sources; if script sources aren't specified, then generation
will default from the ORM metadata.
I've also received feedback (from our JPA/EE integration engineer) that
we need to specify that in Java EE environments that strings corresponding
to file URLs must use absolute (and not relative) paths. I've added that
clarification as well.
Section 8.2.1.9
In the current public draft, this section lacks information as to how
script locations are specified. I've added a clarification that
scripts packaged as part of the application must be specified relative
to the root of the persistence unit, as we do for other packaged
artifacts. I've also added a clarification about the expectations for
use of file URLs in Java EE environments as above.
Finally, when I wrote this up initially, I was reluctant to add
metadata for schema generation actions (including targets) because I
believed that such metadata should not be specific to the persistence
unit definition itself. It seems however that people expect that the
use of these properties (as specified in section 9.4) will be
available anyway, whether they are specified in the spec document or
not, and that some vendors will support these anyway as well.
Further, this additional metadata may facilitate ease of use in
prototyping/development environments. I've therefore added these
properties into 8.2.1.9. If you disagree, please speak up.
thanks,
-Linda