OJB 0.9.8 issues and workarounds

[Scott Howlett <ho...@cadence.com>]

Hello,

I've been playing with OJB 0.9.8 (just using the PersistenceBroker API)
for the past few days. Here are a few gotchas I found, and the
workarounds I've come up with:

1. setStartIndex and setEndIndex don't do anything

Workaround (PostgreSQL-specific): Write a new SqlStatementGenerator that
extends SqlGeneratorDefaultImpl. Override getSelectStatement and
getPrepatedSelectStatement to add " OFFSET xxx LIMIT xxx" to the end of
the statement if startAtIndex or endAtIndex is specified.

By the way, there seems to be an inconsistency in the documentation -
startAtEndex and endAtEndex are initialized to 0, but the javadoc for
Query.setStartIndex() / setEndIndex() states that the "ignore cursor
control" constant is -1.


2. PersistenceBrokerFactory.setDefaultPersistenceBroker() should be
static, but isn't.

Workaround: call
PersistenceBrokerFactoryFactory.instance().setDefaultPersistenceBroker()
instead.


3. If you provide a mapping for an object that includes foreign key
attributes as well as reference objects related to those attributes, and
you just update the foreign key, when you store the object your update
will be clobbered because OJB first resets all foreign keys from the
reference object identities.

Workaround: call persistenceBroker.retrieveAllReferences() on the object
prior to storing it so that any reference objects will be reset based on
your foreign keys.


4. Sometimes an INNER JOIN is used when a LEFT OUTER JOIN ought to be
used:

Let's say I have a "Person" class that has a foreign key reference to a
"Company" class.

If I create a query that looks for all Persons with a
"company.company_name" = "foo", I correctly get an inner join between
user and company on user.company_id=company.id.

But if I create a query that asks for "company.company_name"="foo" OR
"user_name"="foo" I ought to get a left outer join. But I still get an
inner join.

Workaround: Use a report query


I hope this info can be helpful.
Regards,
Scott Howlett