Interesting 1-1/1-M issue with dual keys

Question

Let's say I have a table in my database called COMMENTS that holds comments made about many different kinds of entities in the database. That is, COMMENTS is a table that can be joined with several tables to get comments about that object. For example, I have 3 tables:
COMMENTS
id
objCode
objID
comment
USERS
id
objCode
name
ISSUES
id
objCode
name
With Data:
COMMENTS
1 USER 1 'my comment 1'
2 USER 1 'my comment 2'
3 USER 2 'my comment about a different user'
4 ISSU 1 'my comment about issue 1'
USERS
1 USER 'Bob'
2 USER 'Terry'
ISSUES
1 ISSU 'Important Issue'
So, I have a 1-M relationship between USERS-COMMENTS, and a 1-M relationship between USERS-ISSUES. This works fine.
The problem is in the 1-1 relationship from COMMENTS back to USERS and ISSUES. If I create a 1-1 relationship back on this table I get weird results...Let's focus solely on COMMENTS-USERS
I'm using addForeignKeyFieldName(String, String) on the OneToOneMapping twice to create the mapping from.
addForeignKeyFieldName("COMMENTS.OBJID", "USERS.ID");
addForeignKeyFieldName("COMMENTS.OBJCODE", "USERS.OBJCODE");
It is lazily retrieved. The PROBLEM IS THIS:
If I load up all my COMMENT objects and call "getUser()" on them, EVERY object retuns the USER than matches the "OBJID" value. That is, COMMENT 4 returns USER 1 rather than NULL (it is an ISSUE comment, not a USER comment).
I'm guessing this is related to the way ValueHolders know if there is a cache hit (probably uses the primary key of the object). However, I don't want to make ID/OBJCODE the primary key for USERS, I just want the ValueHolder to get it right on this read.
Is there a way for the ValueHolder in COMMENTS.getUsers() to recognize that a value of 1 for a ISSUE is different than a value of 1 for a USER?

Answer 1

Here is how TopLink will behave in this situation. When you issue the getUser() call, TopLink will take the expression stored in the value holder and check the cache based on the primary key* part of that expression. In you case, it will probably find a match. Then it will use the Mappings of the User object and compare the data in the mappings with the expression. This will not pass in your case, so a cache hit won't happen.
Then the SQL will be issued, and in your case nothing should get returned.
Is SQL getting logged? What type of mapping is you Object code on User being stored in? Is it something other than a direct to field?
*Note this is configurable.  You can set you queries to check by exact primary key, and avoid the cache hit unless the query contains nothing but the primary key.
Peter Krogh