Error moving items between persistent Lists with javax.jdo.option.Optimistic=true and datanucleus.cache.level2.type=none and javax.jdo.annotations.Order(mappedBy="pos") about datanucleus-rdbms HOT 2 CLOSED

If have done some test with release 4.1.0. My current findings are:

My assumptions about test with add only were not correct. In Java if I add an Object contained in one Collection to an other Collection the Object is contained in both Collections afterwards. This is not an error, this is what I have to expect.
If I want move an Object from one Collection to an other I have to remove it from the first and add it to the second Collection.
Java does not know anything about the one-to-many relation.

To get an successfull operation of remove and add I have to obey a strict rule (Relation Management disabled):
I have to set the reference from the Child (Collection member) to the Parent (Collection owner) to null first and remove the the Child from the Collection afterwards.
All other aproaches (not clearing the reference at all or remove the Child from Collection first and set the reference to null afterwards) result in an error (datanucleus tries to delete the Child from the database and ignores the add to the second Collection).

from datanucleus-rdbms.

You have a 1-N and an element in the Collection. You want to just add it to a Collection of a different owner (and set the owner link) without bothering to tell the old owner of this change of ownership. You have not allowed "managed relationships" logic (performed at flush or commit) to run. Consequently this is user error.

Solution : call pm.flush() and then do your test, alternatively handle the remove from the other owner Collection yourself (recommended)

from datanucleus-rdbms.