Django的多数据库与读写分离

1.多个数据库

• settings.py

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    },
    'db2': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db2.sqlite3'),
    },
}

• 迁移其他的数据库

python manage.py migrate --database db2

2.读写分离

2.1手动指定

models.Student.objects.using('db2').all()

obj = models.Student.objects.using('db2').get(name='zhazha')
obj.name = 'star'
obj.save(using='default')

2.4自动选择

• settings配置:

DATABASE_ROUTERS = ['myrouter.Router']

• 创建 router.py

class Router:
    """
    读写分离

    """

    def db_for_write(self, model, **kwargs):
        return 'db2'

    def db_for_read(self, model, **kwargs):
        return 'default'

• 一主多从

class Router:
    """
    一主多从
    """

    def db_for_write(self, model, **kwargs):
        return 'db1'

    def db_for_read(self, model, **kwargs):
        return random.choices['db2', 'db3', 'db4']

• 分库分表

class Router:
    """
    分库分表

    app01  model   db1
    app02  model   db2
    """

    def db_for_write(self, model, **kwargs):
        app_name = model._meta.app_label
        if app_name == 'app01':
            return 'db1'
        elif app_name == 'app02':
            return 'db2'

    def db_for_read(self, model, **kwargs):
        app_name = model._meta.app_label
        if app_name == 'app01':
            return 'db1'
        elif app_name == 'app02':
            return 'db2'