"""A DB backend, based on ``django.db.backends.postgresql_psycopg2`` to cover some specific needs.

The first need is to add the "DEFERRABLE INITIALLY DEFERRED" when defining a unique constraint
on `sort_order` fields, to make the ``Orderable`` base model works correctly.

To use it, simply define it as the engine of your database in django instead of
``django.db.backends.postgresql_psycopg2``:

    >>> DATABASES = {
    ...     'default': {
    ...         'ENGINE': 'mtp.mtp_db_backend',
    ...         #...
    ...     },
    ... }


"""
