Marina-
On Mar 15, 2007, at 5:01 PM, Marina Vatkina wrote:
Hi,
I am part of the GlassFish persistence team and was wondering how
does OpenJPA support JPA auto DDL generation (we call it "java2db")
in a Java EE application server.
Our application server supports java2db via creating two sets of
files for each PU: a ...dropDDL.jdbc and a ...createDDL.jdbc file
on deploy (i.e. before the application is actually loaded into the
container) and then executing 'create' file as the last step in
deployment, and 'drop' file on undeploy or the 1st step in
redeploy. This allows us to drop tables created by the previous
deploy operation.
This approach is done for both, the CMP and the default JPA
provider. It would be nice to add java2db support for OpenJPA as
well, and I'm wondering if we need to do anything special, or it'll
all work just by itself?
We do have support for runtime creation of the schema via the
"openjpa.jdbc.SynchronizeMappings" property. It is described at:
http://incubator.apache.org/openjpa/docs/latest/manual/
manual.html#ref_guide_mapping_synch
The property can be configured to run the mappingtool (also described
in the documentation) at runtime against all the registered
persistent classes.
Here are my 1st set of questions:
1. Which API would trigger the process, assuming the correct values
are specified in the persistence.xml file? Is it:
a) <provider>.createContainerEntityManagerFactory(...)? or
b) the 1st call to emf.createEntityManager() in this VM?
c) something else?
b
2. How would a user drop the tables in such environment?
I don't think it can be used to automatically drop then create
tables. The "mappingtool" can be executed manually twice, the first
time to drop all the tables, and the second time to re-create them,
but I don't think it can be automatically done at runtime with the
"SynchronizeMappings" property.
3. If the answer to either 1a or 1b is yes, how does the code
distinguish between the server startup time and the application
being loaded for the 1st time?
That is one of the reasons why we think it would be inadvisable to
automatically drop tables at runtime :)
4. Is there a mode that allows creating a file with the jdbc
statements to create or drop the tables and constraints?
Yes. See:
http://incubator.apache.org/openjpa/docs/latest/manual/
manual.html#ref_guide_ddl_examples
thank you,
-marina
