Hi Tom
A long time ago we had discussed this as part of introducing java2db
support into the toplink code. At that point of time I had concentrated
on introducing code into the glassfish framework to support this. Based
on the current code base, I think we need to explore this option again.
Below is a very rough proposal that I wanted to run by you. It would be
great to hear your comments on this topic.
_/Problem Description:/_
As you are aware toplink drops the tables from the database based on
the new entities that are part of the current application (pu in the
case of EJB3.0). This is wrong because the entities could have changed
and we should always try to drop the old objects (tables/FKs...)
_/Proposed solution:/_
The code in
glassfish/entity-persistence/src/java/oracle/toplink/essentials/ejb/cmp3/EntityManagerFactoryProvider.java.generateDdlFiles()
is aware of the drop files location and where we need to drop the
entities. Based on the options then it calls
createOrReplaceDefaultTables(). In there we could try to read the drop
file and try to drop the entities. If this fails because the dropFile
does not exist, then the code could continue to do what it does now
(mgr.replaceDefaultTables(true)).
_/Issues to be addressed:/_
If we go down this path, need to do the following
1. read the drop file
2. get a hold of the connection (that is currently used to create the
tables directly in the database if the user has selected the option)
and use that option to execute the statements read as part of 1.
Thanks
Pramod