HHH-4440[1] added the read/write fragment support. However, as reported under HHH-9808[2] that support is not consistent for id column(s). The first piece is missing write fragment support. The second piece is inconsistent application of the read fragments in generated SQL. So as a first question... do we want to support read/write fragments for id column(s)? Assuming yes... Generally speaking we want read/write fragments in reflective pairs, so I am not sure specifically why support for write fragments is not here. I guess there are some cases where it might not make sense (IDENTITY generated columns, e.g.). WDYT? [1] - http://hibernate.atlassian.net/browse/HHH-4440 [2] - http://hibernate.atlassian.net/browse/HHH-9808