The logic used for removing entities from one-to-many list associations can cause ConstraintViolationException will be thrown if there are constraints on both (owner_id, position) and (child_id) in the "collection table". If the association is on a join table, the "collection table" is the join table; otherwise, the "collection table" is the child entity table..

Currently, SchemaExport does not put a constraint on (owner_id, position) when exporting one-to-many list associations on a foreign key. SchemaExport should be updated to also export this constraint.

See HHH-1268 for a description of how to reproduce this issue.

For one-to-many list associations on a foreign key, the workaround is to define the unique constraint on (owner_id, position) in the child entity table as deferred. It is assumed that the primary key in the child entity table is the child ID.

For a one-to-many list association on a join table, the workaround is to define the constraint on (child_id) in the join table as deferred. It is assumed that the primary key in the join table is (owner_id, position).

If your Dialect does not support deferred constraints, then the only workaround is to exclude the unique constraint.