Django Sharding <https://github.com/JBKahn/django-sharding>_
Django Sharding is a library and part-framework for sharding Django applications.
Note: Does not support Django 1.10.3 due to a
bug in the release <https://github.com/JBKahn/django-sharding/issues/48>_.
It helps you to scale your applications by sharding your data across multiple databases in a consistent way.
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What is Sharding? ^^^^^^^^^^^^^^^^^
Sharding is a way of horizontally partitioning your data by storing different rows of the same table in multiple tables across multiple databases. This helps to increase the number of connections to a given resource as well as improves read performance of your application.
Read The Documentation ^^^^^^^^^^^^^^^^^^^^^^
For information about how to setup sharding in your application,
read the documentation <http://josephkahn.io/django-sharding/>_.
Developer Experience ^^^^^^^^^^^^^^^^^^^^
I wrote this library after working on this problem for
Wave <https://www.waveapps.com>_ and not being able to find a library that suited our needs. What we were looking for was something that was powerful, extensible and customizable. This library was created for just that purpose and includes at least one implementation of each part of the pipeline with room to replace any individual components.
The package was influenced by my experiences at Wave as well as the help and code of my co-workers.
Check out the
installation section <http://josephkahn.io/django-sharding/docs/installation/Settings.html>_ of the docs for basic package setup.
Basis Setup & Usage ^^^^^^^^^^^^^^^^^^^
Sharding by User
Select a model to shard by and open up the models.py file. Here we'll use the user model: .. code-block:: python from django.contrib.auth.models import AbstractUser from django_sharding_library.decorators import shard_storage_config from django_sharding_library.models import ShardedByMixin @shard_storage_config() class User(AbstractUser, ShardedByMixin): pass Add that custom User to your settings file using the string class path: .. code-block:: python AUTH_USER_MODEL = '<app_with_user_model>.User' Create Your First Sharded Model
Define your new model, eg:
.. code-block:: python
from django.db import models
from django_sharding_library.decorators import model_config from django_sharding_library.fields import TableShardedIDField from django_sharding_library.models import TableStrategyModel
@model_config(database='default') class ShardedCarIDs(TableStrategyModel): pass
@model_config(sharded=True) class Car(models.Model): id = TableShardedIDField(primary_key=True, source_table_name='app.ShardedCarIDs') ignition_type = models.CharField(max_length=120) company = models.ForeignKey('companies.Company')
def get_shard(self): return self.company.user.shard
Running migrations ^^^^^^^^^^^^^^^^^^
Run them as normal, for example:
./manage.py makemigrations <app_name>
./manage.py migrate --database=<database_alias>
Acccessing sharded data ^^^^^^^^^^^^^^^^^^^^^^^
.. code-block:: python
shard = User.shard Car.objects.using(shard).get(id=123)