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Django orm 中设置读写分离

article 2024/9/22 13:22:41

在 Django ORM 中直接设置读写分离并不像在一些其他数据库框架或系统中那样直接支持。Django ORM 主要关注于数据库的抽象和统一访问，而读写分离通常需要在数据库连接层面或中间件层面进行处理。不过，你可以通过以下几种方法来实现 Django 项目的读写分离：

1. 使用数据库路由（Database Routers）

Django 提供了数据库路由的功能，允许你根据一定的规则来指定模型查询应该使用哪个数据库。这是实现读写分离的一种有效方式。

你需要定义一个或多个数据库路由类，这些类会实现 db_for_read() 和 db_for_write() 方法来指定读操作和写操作应该使用哪个数据库。

class PrimaryReplicaRouter:  
    """  
    A router to control all database operations on models in the  
    auth, contenttypes, and sessions applications, plus any other  
    specified app, to use the "primary" database. Routes all other  
    models to the "replica" database.  
  
    This router is intended as an example, and you can write your  
    own routers to precisely control the location of your data.  
  
    If you want to dynamically set what the primary and replica databases  
    are (perhaps based on the current user), you'll need to implement  
    a method to determine that dynamically.  
    """  
  
    def db_for_read(self, model, **hints):  
        """  
        Attempts to read auth, contenttypes, and sessions models go to primary.  
        """  
        if model._meta.app_label in ('auth', 'contenttypes', 'sessions'):  
            return 'primary'  
        return 'replica'  
  
    def db_for_write(self, model, **hints):  
        """  
        All models' write/save/delete operations use the 'primary' database.  
        """  
        return 'primary'  
  
    def allow_relation(self, obj1, obj2, **hints):  
        """  
        Relations between objects are allowed if both objects are  
        in the primary/replica pool.  
        """  
        db_list = ('primary', 'replica')  
        if obj1._state.db in db_list and obj2._state.db in db_list:  
            return True  
        return None  
  
    def allow_migrate(self, db, app_label, model_name=None, **hints):  
        """  
        Make sure that apps with models that are in the 'primary' pool  
        are only applied in the 'primary' database.  
        """  
        if app_label in ('auth', 'contenttypes', 'sessions'):  
            return db == 'primary'  
        return None

在 settings.py 中，你需要将你的路由添加到 DATABASE_ROUTERS 列表中。