django-缓存

缓存

缓存的定义

缓存案例

查询结束返回给网页消耗时间

缓存优化的思想

缓存场景

配置缓存

数据库缓存

settings配置

本地内存缓存（测试）

雪花算法

文件系统缓存

数据库缓存

settings.py

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': "cache_use",
        'USER':"root",
        "PASSWORD":'password',
        "HOST":"localhost",
        "PORT":'3306'
    }
}

#数据库缓存配置，需手动执行创建命令 'my_cache_table'
CACHES={
"default":{
    "BACKEND":'django.core.cache.backends.db.DatabaseCache',
    "LOCATION":'my_cache_table',
    "TIMEOUT":300,
    "OPTIONS":{
        "MAX_ENTRIES":300,
        "CULL_FREQUENCY":2,
      }
   }
}

执行命令 createcachetable

E:\django_video_study\cache_use\cache_use>python manage.py createcachetable

E:\django_video_study\cache_use\cache_use>python manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, sessions
Running migrations:
  Applying contenttypes.0001_initial... OK
  Applying auth.0001_initial... OK
  Applying admin.0001_initial... OK
  Applying admin.0002_logentry_remove_auto_add... OK
  Applying admin.0003_logentry_add_action_flag_choices... OK
  Applying contenttypes.0002_remove_content_type_name... OK
  Applying auth.0002_alter_permission_name_max_length... OK
  Applying auth.0003_alter_user_email_max_length... OK
  Applying auth.0004_alter_user_username_opts... OK
  Applying auth.0005_alter_user_last_login_null... OK
  Applying auth.0006_require_contenttypes_0002... OK
  Applying auth.0007_alter_validators_add_error_messages... OK
  Applying auth.0008_alter_user_username_max_length... OK
  Applying auth.0009_alter_user_last_name_max_length... OK
  Applying auth.0010_alter_group_name_max_length... OK
  Applying auth.0011_update_proxy_permissions... OK
  Applying sessions.0001_initial... OK

数据库中

mysql> show tables;
+----------------------------+
| Tables_in_cache_use        |
+----------------------------+
| auth_group                 |
| auth_group_permissions     |
| auth_permission            |
| auth_user                  |
| auth_user_groups           |
| auth_user_user_permissions |
| django_admin_log           |
| django_content_type        |
| django_migrations          |
| django_session             |
| my_cache_table             |
+----------------------------+
11 rows in set (0.00 sec)

mysql> desc my_cache_table;
+-----------+--------------+------+-----+---------+-------+
| Field     | Type         | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+-------+
| cache_key | varchar(255) | NO   | PRI | NULL    |       |
| value     | longtext     | NO   |     | NULL    |       |
| expires   | datetime(6)  | NO   | MUL | NULL    |       |
+-----------+--------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

使用缓存---视图函数中

传入的参数为当前视图的时间

使用缓存---路由中

views.py 中配置

import time
from django.shortcuts import HttpResponse
from django.http import request
from django.views.decorators.cache import cache_page
@cache_page(10)
def test_cache(request):
    t=time.time()
    print(t)
    return HttpResponse("当前时间为%d"%(t))

局部缓存

缓存api的使用

In [1]: from django.core.cache import cache
In [2]: #获取default里面的配置项
In [8]: cache.set("us","sjs",20)
In [9]: cache.get("us")
Out[9]: 'sjs'

mysql> select * from my_cache_table \G:;
*************************** 1. row ***************************
cache_key: :1:us
    value: gAWVBwAAAAAAAACMA3Nqc5Qu
  expires: 2021-08-31 01:32:32.000000