[1.6.x] Release notes for ORM changes in 1.6

using non-string keys in ``request.session``. See the

:ref:`session_serialization` documentation for more details.

Object Relational Mapper changes

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django 1.6 contains many changes to the ORM. These changes fall mostly in

three categories:

  1. Bug fixes (e.g. proper join clauses for generic relations, query

     combining, join promotion, and join trimming fixes)

  2. Preparation for new features. For example the ORM is now internally ready

     for multicolumn foreign keys.

  3. General cleanup.

These changes can result in some compatibility problems. For example, some

queries will now generate different table aliases. This can affect

:meth:`QuerySet.extra() <django.db.models.query.QuerySet.extra>`. In addition

some queries will now produce different results. An example is

:meth:`exclude(condition) <django.db.models.query.QuerySet.exclude>`

where the condition is a complex one (referencing multijoins inside

:class:`Q objects <django.db.models.Q>`). In many cases the affected

queries didn't produce correct results in Django 1.5 but do now.

Unfortunately there are also cases that produce different results, but

neither Django 1.5 nor 1.6 produce correct results.

Finally, there have been many changes to the ORM internal APIs.

Miscellaneous

~~~~~~~~~~~~~