django-postgres-extra

django-postgres-extra aims to make all of PostgreSQL's awesome features available through the Django ORM. We do this by taking care of all the hassle. As opposed to the many small packages that are available to try to bring a single feature to Django with minimal effort. django-postgres-extra goes the extra mile, with well tested implementations, seamless migrations and much more.

With seamless we mean that any features we add will work truly seamlessly. You should not have to manually modify your migrations to work with fields and objects provided by this package.

Browse the documentation at: http://django-postgres-extra.readthedocs.io

Major features

• Single query, concurrency safe upserts, or safely ignoring a duplicate insert.

  • https://www.postgresql.org/docs/9.5/static/sql-insert.html#SQL-ON-CONFLICT

• Unique and not null constraints for HStoreField.
• Signals for updates.
• Support for selecting individual hstore keys using .values() or .values_list().

• Support for MIN and MAX.

  • https://www.postgresql.org/docs/8.0/static/functions-aggregate.html

• Support for custom join conditions.

Desired/future features

• Materialized views
• Bulk upserts

Installation

1. Install the package from PyPi:

   $ pip install django-postgres-extra

2. Add postgres_extra and django.contrib.postgres to your INSTALLED_APPS:

   INSTALLED_APPS = [
       ....
   
       'django.contrib.postgres',
       'psqlextra'
   ]

3. Set the database engine to psqlextra.backend:

   DATABASES = {
       'default': {
           ...
           'ENGINE': 'psqlextra.backend'
       }
   }

4. Make sure all models that inherit from psqlextra.models.PostgresModel or use the psqlextra.manager.PostgresManager. Without this, most features do not work.

FAQ - Frequently asked questions

1. Why do I need to change the database back-end/engine?

   We utilize PostgreSQL's hstore data type, which allows you to store key-value pairs in a column. In order to create UNIQUE constraints on specific key, we need to create a special type of index. We could do this without a custom database back-end, but it would require everyone to manually write their migrations. By using a custom database back-end, we added support for this. When changing the uniqueness constraint on a HStoreField, our custom database back-end takes care of creating, updating and deleting these constraints/indexes in the database.

2. I am already using a custom database back-end, can I still use yours?

   Yes. You can set the POSTGRES_EXTRA_DB_BACKEND_BASE setting to your current back-end. This will instruct our custom database back-end to inherit from the database back-end you specified. Warning: this will only work if the base you specified indirectly inherits from the standard PostgreSQL database back-end.

3. Does this package work with Python 2?

   No. Only Python 3.5 or newer is supported. We're using type hints. These do not work well under older versions of Python.

4. Does this package work with Django 1.X?

   No. Only Django 1.10 or newer is supported.