bwstearns / django-cassandra-engine

Django Cassandra Engine - the Cassandra backend for Django

Django Cassandra Engine

django-cassandra-engine is a database wrapper for Django Framework. It uses latest Cqlengine which is currently the best Cassandra CQL 3 Object Mapper for Python.

License:	2-clause BSD
Keywords:	django, cassandra, orm, nosql, database, python
URL (pypi):	django-cassandra-engine

Requirements

• cassandra
• cqlengine
• django-nonrel
• djangotoolbox
• django (1.6 or 1.7)

Features

• complete Django integration
• working syncdb and flush commands
• support for creating/destroying test database
• accept all Cqlengine connection options
• automatic connection/disconnection handling
• support for multiple databases (also relational)

Installation

Recommended installation:

pip install django-cassandra-engine

Usage

1. Add django-cassandra-engine to INSTALLED_APPS in your settings.py file:

   INSTALLED_APPS += ('django_cassandra_engine',)
   

IMPORTANT: This app should be last on INSTALLED_APPS list.

1. Also change DATABASES setting:

   DATABASES = {
       'default': {
           'ENGINE': 'django_cassandra_engine',
           'NAME': 'db',
           'TEST_NAME': 'test_db',
           'HOST': 'db1.example.com,db2.example.com',
           'OPTIONS': {
               'replication': {
                   'strategy_class': 'SimpleStrategy',
                   'replication_factor': 1
               }
           }
       }
   }
   

2. Define some model:

   #  myapp/models.py
   import uuid
   from cqlengine import columns
   from cqlengine.models import Model
   
   class ExampleModel(Model):
       read_repair_chance = 0.05 # optional - defaults to 0.1
       example_id      = columns.UUID(primary_key=True, default=uuid.uuid4)
       example_type    = columns.Integer(index=True)
       created_at      = columns.DateTime()
       description     = columns.Text(required=False)
   

3. Run ./manage.py syncdb

4. Done!

Advanced usage

Sometimes you want to use cassandra database along with your RDMS. This is also possible! Just define your DATABASES like here:

from django_cassandra_engine.connection import ConsistencyLevel

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    },
    'cassandra': {
        'ENGINE': 'django_cassandra_engine',
        'NAME': 'db',
        'TEST_NAME': 'test_db',
        'HOST': '127.0.0.1',
        'OPTIONS': {
            'replication': {
                'strategy_class': 'SimpleStrategy',
                'replication_factor': 1
            },
            'connection': {
                'consistency': ConsistencyLevel.ONE,
                'lazy_connect': False,
                'retry_connect': False
                # + All connection options for cassandra.Cluster()
            }
        }
    }
}

Then run ./manage.py syncdb for your regular database and ./manage.py syncdb --database cassandra for Cassandra DB.

Links

• Changelog