mysql主从复制

　　2. 从库配置

[mysqld]
character-set-server=utf8
collation-server=utf8_general_ci
server-id=101
log-bin=mysql-slave-bin
relay_log=edu-mysql-relay-bin

[client]
default-character-set=utf8

[mysql]
default-character-set=utf8

三: 操作步骤

四: Python代码的实现(读写分离)

　　1. 实现读写分离的准备

　　settings.py配置

DATABASES = {
    ‘default‘: {
        ‘ENGINE‘: ‘django.db.backends.mysql‘,
        ‘NAME‘: ‘test‘,
        ‘USER‘: ‘root‘,
        ‘PASSWORD‘: ‘123456‘,
        ‘HOST‘: ‘39.105.40.122‘,
        ‘PORT‘: 33307,
    },
    ‘slave‘: {
        ‘ENGINE‘: ‘django.db.backends.mysql‘,
        ‘NAME‘: ‘test‘,
        ‘USER‘: ‘root‘,
        ‘PASSWORD‘: ‘123456‘,
        ‘HOST‘: ‘39.105.40.122‘,
        ‘PORT‘: 33306,
    }
}
DATABASE_ROUTERS = [‘router.Router1‘,]

　　views.py

from django.shortcuts import render,HttpResponse

# Create your views here.
from app01.models import Book
def index(request):
    # Book.objects.using("default").create(title="xx",price=10)
    # ret=Book.objects.all().using("slave")
    #using 是queryset对象的方法
    # print(ret)
    # Book.objects.create(title="yyy", price=100)
    ret = Book.objects.all()
    print(ret)
    return HttpResponse(‘ok‘)

　　创建router.py文件

class Router1:
　　# 只读数据库
    def db_for_read(self, model, **hints):
        """
        Attempts to read auth models go to auth_db.
        """
        return ‘slave‘

　　# 只写数据库
    def db_for_write(self, model, **hints):
        """
        Attempts to write auth models go to auth_db.
        """
        return ‘default‘

　　# 数据库进行迁移的时候进行约束(但不会报错)
    def allow_migrate(self, db, app_label, model_name=None, **hints):
        # print("zzzz")
        if db == ‘slave‘ and app_label=="app01":

            return False

　　2. 实现读写分离(手动和自动操作)

　　2.1 共同操作　　

python manage.py makemigrations
# python manage.py  migrate app名字 --database=配置文件数据库名称   注意: 写数据库
python manage.py migrate app01 --database=default

　　2.2 手动操作(一般不使用)

# 用using说明你要往哪个库写还是读
models.UserType.objects.using(‘default‘).create(title=‘普通用户‘)
result = models.UserType.objects.all().using(‘slave‘)

　　2.3自动操作

　　创建router.py文件(在里面写入如上面的router.py文件)

问题: (分库)

　　app01中的表在default数据库创建

　　app02中的表在db1数据库创建

　　如何解决不同的应用使用不同的数据库?

实现步骤:(settings配置如上)

　　1.

python manage.py makemigrations

　　2.

# app01中的表在default数据库创建
python manage.py migrate app01 --database=default

　　3.

# app02中的表在db1数据库创建
python manage.py migrate app02 --database=db1

　　手动操作

m1.UserType.objects.using(‘default‘).create(title=‘VVIP‘)
m2.Users.objects.using(‘db1‘).create(name=‘VVIP‘,email=‘xxx‘)

　　自动操作

class Router1:
    def db_for_read(self, model, **hints):
        """
        Attempts to read auth models go to auth_db.
        """
        if model._meta.app_label == ‘app01‘:
            return ‘default‘
        else:
            return ‘db1‘

    def db_for_write(self, model, **hints):
        """
        Attempts to write auth models go to auth_db.
        """
        if model._meta.app_label == ‘app01‘:
            return ‘default‘
        else:
            return ‘db1‘


DATABASE_ROUTERS = [‘db_router.Router1‘, ]

# 使用：
m1.UserType.objects.using(‘default‘).create(title=‘VVIP‘)
m2.Users.objects.using(‘db1‘).create(name=‘VVIP‘, email=‘xxx‘)


# 其他：
class Router1:
    # 数据库迁移时进行约束：
    def allow_migrate(self, db, app_label, model_name=None, **hints):
        """
        All non-auth models end up in this pool.
        """
        if db == ‘db1‘ and app_label == ‘app02‘:
            return True
        elif db == ‘default‘ and app_label == ‘app01‘:
            return True
        else:
            return False

    # 如果返回None，那么表示交给后续的router，如果后续没有router，则相当于返回True

    def db_for_read(self, model, **hints):
        """
        Attempts to read auth models go to auth_db.
        """
        if model._meta.app_label == ‘app01‘:
            return ‘default‘
        else:
            return ‘db1‘

    def db_for_write(self, model, **hints):
        """
        Attempts to write auth models go to auth_db.
        """
        if model._meta.app_label == ‘app01‘:
            return ‘default‘
        else:
            return ‘db1‘

mysql主从复制

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