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文章目录
- Redis !
- 一、概述
- 二、安装
- 三、实操
- 1、性能测试
- 2、基础知识
- 3、基本key命令
- 4、基本数据类型
- 1、String
- 2、List
- 3、Set
- 4、Hash
- 5、Zset
- 5、特殊类型
- 1、Geospatial
- 2、Hyperloglog
- 3、Bitmap
- 6、事务
- 1、基本概念
- 2、命令
- 3、错误
- 7、乐观锁
- 四、Jedis
- 1、远程连接配置
- 五、整合springboot
- 1、整合
- 2、自定义RedisTemplate
- 六、配置文件详解
- 七、持久化
- 1、rdb
- 2、aof
- 3、rdb与aof相比
- 八、订阅发布
- 九、集群
- 1、环境搭建
- 2、主从复制
- 3、手动配置主机
- 4、哨兵模式
- 十、缓存相关问题
Redis !
前记:
- 文字教程:https://www.runoob/redis/redis-tutorial.html
- 官网:https://redis.io/
- 视频教程(感谢狂神!):https://www.bilibili/video/BV1S54y1R7SB?from=search&seid=8828140793255514658
- 在学数据操作的时候,深深感受到什么叫基础不牢地动山摇。是时候该多花点时间在算法和数据结构上了。
- 师兄推荐书籍:《redis的设计与实现》,原理层面的。
一、概述
-
简要发展历程
- 单机mysql
- 垂直拆分(读写分离) + 缓存
- 集群(数据拆分) + 分表分库
-
NoSql特点
-
方便扩展(数据之间没有关系,很好扩展)
-
大数据量高性能(Redis 一秒写8W次,读11W次。缓存是细粒度的,性能高)
-
数据类型是多样的(不用事先设计数据库,随取随用)
-
传统RDBMS与NoSql
RDBMS - 结构化组织 - 用sql查询 - 数据和关系都在单独的表中 - 严格的一致性 - 事务
Nosql - 不仅仅是数据 - 没有固定的语言 - 键值对存储,列存储,文档存储,图关系数据库 (四大分类) - 最终一致性 - 高性能,高可用,高可扩
-
-
Redis
- remote dictionary server 远程字典服务
- key-value型的nosql数据库
- 能干嘛
- 内存存储,持久化(rdb、aof)
- 效率高,可用于调整缓存
- 发布订阅系统
- 地图信息分析
- 计时器、计数器(浏览量)
- 特性
- 多样的数据类型
- 持久化
- 集群
- 事务
二、安装
-
下载https://redis.io/download
-
tar -zxvf 包名
解压 -
环境准备
yum -y gcc-c++ #安装c++环境
在解压的目录下:
make #执行安装 make install #再次执行安装
-
默认安装路径:/usr/local/bin/目录
运行的配置文件默认路径:解压的目录/redis.config
-
修改配置文件中:
修改的目的是让redis能在后台运行
#原来: daemonize no #修改为 daemonize yes
-
启动服务
redis-server redis.conf
指定以哪个配置文件来启动 -
连接
redis-cli -h localhost -p 6379
(默认为本机,6379为默认端口号)ping
正常连接可以得到pong回应 -
退出
shutdown
关机,成为未连接状态再
exit
退出
三、实操
1、性能测试
命令格式:
redis-benchmark [option] [option value]
命令参数:
序号 | 选项 | 描述 | 默认值 |
---|---|---|---|
1 | -h | 指定服务器主机名 | 127.0.0.1 |
2 | -p | 指定服务器端口 | 6379 |
3 | -s | 指定服务器 socket | |
4 | -c | 指定并发连接数 | 50 |
5 | -n | 指定请求数 | 10000 |
6 | -d | 以字节的形式指定 SET/GET 值的数据大小 | 2 |
7 | -k | 1=keep alive 0=reconnect | 1 |
8 | -r | SET/GET/INCR 使用随机 key, SADD 使用随机值 | |
9 | -P | 通过管道传输 请求 | 1 |
10 | -q | 强制退出 redis。仅显示 query/sec 值 | |
11 | –csv | 以 CSV 格式输出 | |
12 | -l | 生成循环,永久执行测试 | |
13 | -t | 仅运行以逗号分隔的测试命令列表。 | |
14 | -I | Idle 模式。仅打开 N 个 idle 连接并等待。 |
例子:
对本机6379端口号的redis, 进行200并发量的20000次请求测试。
redis-benchmark -h localhost -p 6379 -c 200 -n 20000
2、基础知识
-
redis默认有16个数据库。默认使用第0号数据库
# Set the number of databases. The default database is DB 0, you can select # a different one on a per-connection basis using SELECT <dbid> where # dbid is a number between 0 and 'databases'-1 databases 16
-
select [index] 选择切换到第index号数据库
-
dbsize查看当前数据库的大小
-
keys * 查看所有的key
-
flushdb清空当前数据库的所有数据
-
flushall清空所有数据库的所有数据
经典问题:为什么redis使用单线程,而不使用多线程?单线程还这么快
误区:多线程一定比单线程快。
- redis是基于内存来操作的,cpu不是redis的瓶颈,内存大小和宽带才是
- 多线程下,线程切换cpu要频繁切换上下文,会更浪费时间
- 因为不是基于cpu来操作,对内存来说,如果没有上下文切换,使用单线程就是效率最高的
简答三点:
- 基于内存
- 多线程多耗
- 内存操作与多线程关系
3、基本key命令
127.0.0.1:6379> keys * #查看当前库所有的键名
1) "key2"
2) "key"
3) "name"
127.0.0.1:6379> move name 1 #把name移动到1号数据库
(integer) 1
127.0.0.1:6379> set name hello #设置key - value
OK
127.0.0.1:6379> get name #根据key得到value
hello
127.0.0.1:6379> exists name #判断当前库是否存在键
(integer) 1
127.0.0.1:6379> expire name 10 # 设置key的过期时间,s为单位
(integer) 1
127.0.0.1:6379> ttl name #查看key还有多少秒过期
(integer) 5
127.0.0.1:6379>
127.0.0.1:6379> type name #查看value的类型
string
4、基本数据类型
1、String
- 和java中的很多方法相同,相同的低层原因是:数据结构是相通的!
-
字符操作
- 追加:
append key "追加的字符"
- 得到长度:
strlen key
得到字符长度 - 截取:
getrange key start end
是闭区间! [start, end]。 把end设置成-1, 则是得到从start到最后面的所有字符。 - 范围设置:
setrange key start "设置的字符串"
从一个开始的位置替换! - 删除:
del key
- 追加:
-
自增模式(必须是integer类型)
- 自增:
incr key
- 自减:
decr key
- 自定义步长:
incrby key 步长
- 自定义步长:
decrby key 步长
- 自增:
-
条件设置
setnx key value
set key = value if key not exists 如果key不存在,则设置一个key。直接set会替换原来的值setex key value 过期时间
set with expire 时间。设置一个key,并规定其过期时间。相当于set 和 expire 命令同时使用getset key "新的值"
得到旧的值返回,并设置新的值- 批量设置:
mset k1 v1 k2 v2 k3 v3
- 批量存在设置:
msetnx k1 v1 k2 v2 k3 v3
是一个原子性操作,要么同时成功,要么同时失败 - 批量得到:
mget k1 k2
-
对象层级设置
127.0.0.1:6379> mset user:1:name name1 user:2:name name2 user:1:pwd pwd1 user:2:pwd pwd2 OK 127.0.0.1:6379> keys * 1) "user:1:name" 2) "user:1:pwd" 3) "user:2:pwd" 4) "user:2:name"
2、List
基本知识
- 是一个链表,含首尾指针的双向链表
- 对端操作效率高,对中间元素操作效率低
- 前面带 l 代表list 的相关操作,默认为左边(或者理解为从左边开始)。如果带r, 则是从右边操作。
- 如果只有一层含义,一般只有l;如果有对称含义,一般有l 和 r 。比如lrange查看元素,从左边和右边查看都是一样的,故没有rrange。又如lpop, 从左边弹出和从右边弹出是不一样的,故有rpop。
API
- 插入移除
lpush mylist elements
向左插入lpop mylist 个数
向左弹出多少个元素,不写默认为1rpush mylist elements
向右插入元素rpop mylist 个数
向右弹出多少个元素,不写默认为1
- 查看
lrange mylist startIndex endIndex
查看从startIndex到endIndex闭区间的元素。如果endIndex = -1, 则是查看从startIndex到最后所有的元素Llen mylist
查看列表长度。(注意redis不区分大小写,把llen写成Len有助于查看)
- 修改
Lrem mylist 个数 元素值名
移除多少个指定的元素。从左边算起,没有RremLtrim mylist startIndex endIndex
把闭区间内的元素截取出来,即其它元素全部去掉RpopLpush <source> <destination>
把源列表中最后一个元素右弹出,然后左插入到目的列表中去。如果source == destination , 则相当于一个列表循环Lset mylist index element
对指定下标的元素进行替换。如果key 或 index 不存在,则会报错Linsert mylist <before|after> pivot(中心元素) element
以中心元素为中心,向前向后插入。有重复的话,还是默认从左边开始找,并以第一个元素为中心。
- 判断
exists mylist
判断是否存在。和普通字符的判断一致。
3、Set
基本知识
- 这个set可以完全理解为数学中的集合!!!
- 两个特点:无序,无重复
- 命令以s开头,代表set
- 应用:共同关注,二度好友等,A -> b <-C, 用AC作交
API
- 添加移除
Sadd myset element1 element2 element3
向一个集合中添加元素Srem myset element1 element2 element3
对一个集合移除元素Spop myset count
随机删除count个元素。不写默认为一个Smove sourceSet destinationSet member
把指定元素从一个集合移动到另一个集合中
- 查看
Smembers myset
查看指定集合中所有的元素Scard myset
查看集合中元素的个数SrandMember myset 个数
随机查看元素中的个数。不写个数默认查看一个
- 集合操作
- 差集:
Sdiff myset1 myset2
以myset1为中心,作myset1 / myset2 的差集。可以理解为myset1集合中特有的元素 - 并集:
Sunion myset1 myset2 myset3
把所有集合作并 - 交集(intersection):
Sinter myset1 myset2 myset3
把所有集合作交
- 差集:
4、Hash
把key叫做field是官方叫法。key是myhash
-
字符操作
hset myhash k1 v1
为一个hash设置k1 v1 (经过测试,这也是可以设置多个值的)hget myhash k1
向一个hash得到一个key中的valuehgetall myhash
得到所有的键值对hkeys myhash
得到所有的键hvals myhash
得到所有的值hdel myhash k1 k2 k3
删除指定的键值对hlen myhash
得到长度
-
自增模式
hincrby myhash k1 increment
对某个键进行自增- 自减的话,把increment变成负数即可。从官网中查知,没有hdecrby的命令。只有两个个跟自增相关的命令(另一个是hincrbyfloat,浮点数)。
-
条件
hmset myhash k1 v1 k2 v2 k3 v31
设置多个值hmget myhash k1 k2 k3
得到多个值hexists myhash key
判断hash中是否存在指定的key
-
对象层级
虽然普通的key-value也可以存对象,但hash存对象明显更合适。
127.0.0.1:6379> hmset user:1 name wenhao age 18 OK 127.0.0.1:6379> hgetall user:1 1) "name" 2) "wenhao" 3) "age" 4) "18" 127.0.0.1:6379> hmset user:2 name wenwen age 19 OK 127.0.0.1:6379> hgetall user:2 1) "name" 2) "wenwen" 3) "age" 4) "19"
5、Zset
基础知识
- 是一个有序集合
- 应用:
- 工资表排序
- 重要消息,带权重判断
- 排行榜的应用
API
- 添加移除
zadd myzset score(权重) 值
向一个有序集合中添加权重并加入值zrem myzset k1 k2 k3
移除一个或者多个值
- 查看
zrange myzset startIndex endIndex
查询从startIndex 到endIndex中的元素。startIndex和endIndex是按照score的大小从小到大排序后赋予的,并不是按照添加入的顺序赋予的。zrevrange myzset startIndex endIndex
是上面命令的反转zcard myzset
查看集合大小zcount myzset min max
统计score在min和max范围内的值的个数
- 排序
zrangebyscore myzset min max [withscore]
把score在min到max范围的值输出zrevrangebyscore myzset min max [withscore]
反转
5、特殊类型
1、Geospatial
-
geoadd
geoadd mygeo longtitude latutude beijing(name)
-
geopos
geopos mygeo name
得到指定name的经纬度 -
geodist (distance)
geodis mygeo name1 name2
得到两个位置的直线距离 -
georadius
georadius mygeo mylongtitude mylatitude n km
以当前我的位置,n千米为半径的所有地理元素 -
georadiusbymember
georadiusbymember mygeo name1 n km
以某个地理元素,n千米为半径的所有地理元素 -
geohash
geohash mygeo name
得到指定地理元素经纬度的11位字符串表示,是把二维的降为一维 -
底层是Zset实现的,可以使用Zet命令对Geospatial进行操作
如
Zrange mygeo 0 -1
Zrem mygeo name1
2、Hyperloglog
- 用于计算集合中的基数(即不同元素的个数)
- 占用空间小(固定12kb)(自行查询原理),但有0.81%的错误率
- 在统计网点访问量时,允许有小误差,因此可以用Hyperloglog
- 可以用set来等价实现,但set占用空间和Hyperloglog相比,非常大
- 不能查看存入的元素值(与所用的算法有关)
127.0.0.1:6379> PFadd myset1 a b c d e f #创建并加入
(integer) 1
127.0.0.1:6379> PFadd myset2 e f g h i j
(integer) 1
127.0.0.1:6379> PFcount myset1 #统计单个
(integer) 6
127.0.0.1:6379> Pfcount myset1 myset2 #统计多个,(不合并下统计)
(integer) 10
127.0.0.1:6379> PFmerge myset3 myset1 myset2 #合并
OK
127.0.0.1:6379> PFcount myset3
(integer) 10
127.0.0.1:6379>
3、Bitmap
- 如果事情只有两个状态,那么就可以使用
- 是对位进行操作的
127.0.0.1:6379> setbit mybitmap 1 0
(integer) 0
127.0.0.1:6379> setbit mybitmap 2 1
(integer) 0
127.0.0.1:6379> setbit mybitmap 3 1
(integer) 0
127.0.0.1:6379> setbit mybitmap 4 1
(integer) 0
127.0.0.1:6379> setbit mybitmap 5 1
(integer) 0
127.0.0.1:6379> setbit mybitmap 6 1
(integer) 0
127.0.0.1:6379> setbit mybitmap 7 0 #setbit mybitmap 对应位 状态
(integer) 0
127.0.0.1:6379> getbit mybitmap 0 #得到对应位的状态
(integer) 0
127.0.0.1:6379> getbit mybitmap 2
(integer) 1
127.0.0.1:6379> bitcount mybitmap #统计bitmap中1状态的数量
(integer) 5
6、事务
1、基本概念
-
Redis事务的本质:一组命令的集合
-
一个事务中所有命令都会被序列化,在事务执行过程中,会按照顺序执行
-
Redis事务模型:在执行命令发送前,所有的命令都不会被执行
-------开始事务 命令入队列 命令1 命令2 命令3 执行------
-
Redis事务特性
- 一次性:所有命令都会被执行
- 顺序性:按入队顺序执行
- 排他性:不允许被别人干扰(不是指内容,而是指事务这件事)
-
在Mysql中,事务的设计遵从4大原则,但在Redis中,单条命令保证原子性,但是事务不保证原子性
-
Redis事务没有隔离级别的概念,也就没有什么脏读之类的问题
2、命令
- 开启事务:
multi
- 命令入列:。。。。
- 执行事务:
exec
- 放弃事务:
discard
3、错误
- 编译型错误:语法本身有问题,编译都不通过!如果执行exec, 那么所有队列中的命令都不会被执行
- 运行时错误:语法没有问题,在执行过程中才有错误,那么除了有错误的命令外,其他正确的命令都会被执行
7、乐观锁
基本概念
- 悲观锁:
- 很悲观,认为在什么时候都会出现问题,无论做什么都会加锁
- 乐观锁:
- 很乐观,认为什么时候都不会出问题,所以不会上锁
- 原理:在更新数据的时候去判断一下,在此期间是否有人修改过这个数据
- (获取version, 更新的时候比较version)
操作
watch key
对指定的key进行监视unwatch
放弃对所有的key的监视
正常执行:
127.0.0.1:6379> set money 100
OK
127.0.0.1:6379> watch money #监视某个key
OK
127.0.0.1:6379> multi
OK
127.0.0.1:6379(TX)> decrby money 10
QUEUED
127.0.0.1:6379(TX)> exec #正常执行
1) (integer) 90
线程插队:
进程一:
127.0.0.1:6379> set money 90
OK
127.0.0.1:6379> watch money
OK
127.0.0.1:6379> multi
OK
127.0.0.1:6379(TX)> decrby money 10
QUEUED
-------------------------------------------------------------
进程二在此时插队执行并修改了监视的数据:
127.0.0.1:6379> get money
"90"
127.0.0.1:6379> set money 100
OK
--------------------------------------------------------------
127.0.0.1:6379(TX)> exec
(nil) #此时会执行失败!!!!
四、Jedis
1、远程连接配置
-
修改配置文件
修改的地方有三处: 一:注释bind 127.0.0.1 二:将protected-mode yes改为protected-mode no 三:配置密码,将requirepass的‘#’去掉,后面填写远程连接密码 requirepass 123456
-
用新的配置文件重启。
-
服务器本地测试连接
连接上后, auth 密码 进行本地验证
-
完事后即可用Java进行连接
-
可能会遇到防火墙问题:(阿里云记得配置安全组规则)
#连接失败,关闭Centos防火墙。Centos下关闭防火墙命令为 sudo systemctl stop firewalld.service #停止firewall sudo systemctl disable firewalld.service #禁止firewall开机启动
-
测试:
public class TestMain { public static void main(String[] args) { Jedis jedis = new Jedis("服务器ip", 6379); jedis.auth("123456"); jedis.set("name", "hao"); String name = jedis.get("name"); System.out.println(name); jedis.close(); } }
五、整合springboot
- 在springboot2.x之后,底层使用lettuce而不是jedis, 区别具体查询
1、整合
-
导入依赖
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-redis</artifactId> </dependency>
-
配置
spring: redis: host: 主机名,默认为localhost port: 6379 password: 123456
-
测试
@Autowired RedisTemplate<String, String> redisTemplate; //注入操作模板 @Test void contextLoads() { //与字符串相关操作 redisTemplate.opsForValue().set("name", "haohao"); String name = redisTemplate.opsForValue().get("name"); System.out.println(name); }
2、自定义RedisTemplate
因为默认使用jdk序列化,在存入Redis数据库时,会出现乱码。
@Configuration
public class RedisConfig {
@Bean
@SuppressWarnings("all")
public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory connectionFactory) {
RedisTemplate<String, Object> template = new RedisTemplate<>();
template.setConnectionFactory(connectionFactory);
//上面都是默认的
//自定义Jackson序列化配置
Jackson2JsonRedisSerializer jsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
objectMapper.activateDefaultTyping(LaissezFaireSubTypeValidator.instance, DefaultTyping.NON_FINAL);
jsonRedisSerializer.setObjectMapper(objectMapper);
//key使用String的序列化方式
StringRedisSerializer stringRedisSerializer = new StringRedisSerializer();
template.setKeySerializer(stringRedisSerializer);
//hash的key也是用String的序列化方式
template.setHashKeySerializer(stringRedisSerializer);
//value的key使用jackson的序列化方式
template.setValueSerializer(jsonRedisSerializer);
//hash的value也是用jackson的序列化方式
template.setHashValueSerializer(jsonRedisSerializer);
template.afterPropertiesSet();
return template;
}
}
六、配置文件详解
命令行可以临时改变配置:
config get 配置项名
config set 配置项名 配置值
# Redis configuration file example.
#
# Note that in order to read the configuration file, Redis must be
# started with the file path as first argument:
#
# ./redis-server /path/to/redis.conf
# Note on units: when memory size is needed, it is possible to specify
# it in the usual form of 1k 5GB 4M and so forth:
#
规定了基本单位
# 1k => 1000 bytes
# 1kb => 1024 bytes
# 1m => 1000000 bytes
# 1mb => 1024*1024 bytes
# 1g => 1000000000 bytes
# 1gb => 1024*1024*1024 bytes
#
这里说明Redis大小写不敏感
# units are case insensitive so 1GB 1Gb 1gB are all the same.
################################## INCLUDES ###################################
# Include one or more other config files here. This is useful if you
# have a standard template that goes to all Redis servers but also need
# to customize a few per-server settings. Include files can include
# other files, so use this wisely.
#
# Note that option "include" won't be rewritten by command "CONFIG REWRITE"
# from admin or Redis Sentinel. Since Redis always uses the last processed
# line as value of a configuration directive, you'd better put includes
# at the beginning of this file to avoid overwriting config change at runtime.
#
# If instead you are interested in using includes to override configuration
# options, it is better to use include as the last line.
#
说明可以从外部文件中包含配置,相当于jsp中的include标签
# include /path/to/local.conf
# include /path/to/other.conf
################################## MODULES #####################################
# Load modules at startup. If the server is not able to load modules
# it will abort. It is possible to use multiple loadmodule directives.
#
# loadmodule /path/to/my_module.so
# loadmodule /path/to/other_module.so
################################## NETWORK #####################################
# By default, if no "bind" configuration directive is specified, Redis listens
# for connections from all available network interfaces on the host machine.
# It is possible to listen to just one or multiple selected interfaces using
# the "bind" configuration directive, followed by one or more IP addresses.
# Each address can be prefixed by "-", which means that redis will not fail to
# start if the address is not available. Being not available only refers to
# addresses that does not correspond to any network interfece. Addresses that
# are already in use will always fail, and unsupported protocols will always BE
# silently skipped.
#
# Examples:
#
# bind 192.168.1.100 10.0.0.1 # listens on two specific IPv4 addresses
# bind 127.0.0.1 ::1 # listens on loopback IPv4 and IPv6
# bind * -::* # like the default, all available interfaces
#
# ~~~ WARNING ~~~ If the computer running Redis is directly exposed to the
# internet, binding to all the interfaces is dangerous and will expose the
# instance to everybody on the internet. So by default we uncomment the
# following bind directive, that will force Redis to listen only on the
# IPv4 and IPv6 (if available) loopback interface addresses (this means Redis
# will only be able to accept client connections from the same host that it is
# running on).
#
# IF YOU ARE SURE YOU WANT YOUR INSTANCE TO LISTEN TO ALL THE INTERFACES
# JUST COMMENT OUT THE FOLLOWING LINE.
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
bind绑定ip,限定只能用该ip来连接客户端
#bind 127.0.0.1 -::1
# Protected mode is a layer of security protection, in order to avoid that
# Redis instances left open on the internet are accessed and exploited.
#
# When protected mode is on and if:
#
# 1) The server is not binding explicitly to a set of addresses using the
# "bind" directive.
# 2) No password is configured.
#
# The server only accepts connections from clients connecting from the
# IPv4 and IPv6 loopback addresses 127.0.0.1 and ::1, and from Unix domain
# sockets.
#
# By default protected mode is enabled. You should disable it only if
# you are sure you want clients from other hosts to connect to Redis
# even if no authentication is configured, nor a specific set of interfaces
# are explicitly listed using the "bind" directive.
保护模式,如果要远程连接,要把保护模式关闭
protected-mode no
# Accept connections on the specified port, default is 6379 (IANA #815344).
# If port 0 is specified Redis will not listen on a TCP socket.
连接的端口号
port 6379
# TCP listen() backlog.
#
# In high requests-per-second environments you need a high backlog in order
# to avoid slow clients connection issues. Note that the Linux kernel
# will silently truncate it to the value of /proc/sys/net/core/somaxconn so
# make sure to raise both the value of somaxconn and tcp_max_syn_backlog
# in order to get the desired effect.
tcp-backlog 511
# Unix socket.
#
# Specify the path for the Unix socket that will be used to listen for
# incoming connections. There is no default, so Redis will not listen
# on a unix socket when not specified.
#
# unixsocket /run/redis.sock
# unixsocketperm 700
# Close the connection after a client is idle for N seconds (0 to disable)
设置连接无反应时,关闭连接
timeout 0
# TCP keepalive.
#
# If non-zero, use SO_KEEPALIVE to send TCP ACKs to clients in absence
# of communication. This is useful for two reasons:
#
# 1) Detect dead peers.
# 2) Force network equipment in the middle to consider the connection to be
# alive.
#
# On Linux, the specified value (in seconds) is the period used to send ACKs.
# Note that to close the connection the double of the time is needed.
# On other kernels the period depends on the kernel configuration.
#
# A reasonable value for this option is 300 seconds, which is the new
# Redis default starting with Redis 3.2.1.
tcp-keepalive 300
################################# TLS/SSL #####################################
# By default, TLS/SSL is disabled. To enable it, the "tls-port" configuration
# directive can be used to define TLS-listening ports. To enable TLS on the
# default port, use:
#
# port 0
# tls-port 6379
# Configure a X.509 certificate and private key to use for authenticating the
# server to connected clients, masters or cluster peers. These files should be
# PEM formatted.
#
# tls-cert-file redis.crt
# tls-key-file redis.key
# Normally Redis uses the same certificate for both server functions (accepting
# connections) and client functions (replicating from a master, establishing
# cluster bus connections, etc.).
#
# Sometimes certificates are issued with attributes that designate them as
# client-only or server-only certificates. In that case it may be desired to use
# different certificates for incoming (server) and outgoing (client)
# connections. To do that, use the following directives:
#
# tls-client-cert-file client.crt
# tls-client-key-file client.key
# Configure a DH parameters file to enable Diffie-Hellman (DH) key exchange:
#
# tls-dh-params-file redis.dh
# Configure a CA certificate(s) bundle or directory to authenticate TLS/SSL
# clients and peers. Redis requires an explicit configuration of at least one
# of these, and will not implicitly use the system wide configuration.
#
# tls-ca-cert-file ca.crt
# tls-ca-cert-dir /etc/ssl/certs
# By default, clients (including replica servers) on a TLS port are required
# to authenticate using valid client side certificates.
#
# If "no" is specified, client certificates are not required and not accepted.
# If "optional" is specified, client certificates are accepted and must be
# valid if provided, but are not required.
#
# tls-auth-clients no
# tls-auth-clients optional
# By default, a Redis replica does not attempt to establish a TLS connection
# with its master.
#
# Use the following directive to enable TLS on replication links.
#
# tls-replication yes
# By default, the Redis Cluster bus uses a plain TCP connection. To enable
# TLS for the bus protocol, use the following directive:
#
# tls-cluster yes
# By default, only TLSv1.2 and TLSv1.3 are enabled and it is highly recommended
# that older formally deprecated versions are kept disabled to reduce the attack surface.
# You can explicitly specify TLS versions to support.
# Allowed values are case insensitive and include "TLSv1", "TLSv1.1", "TLSv1.2",
# "TLSv1.3" (OpenSSL >= 1.1.1) or any combination.
# To enable only TLSv1.2 and TLSv1.3, use:
#
# tls-protocols "TLSv1.2 TLSv1.3"
# Configure allowed ciphers. See the ciphers(1ssl) manpage for more information
# about the syntax of this string.
#
# Note: this configuration applies only to <= TLSv1.2.
#
# tls-ciphers DEFAULT:!MEDIUM
# Configure allowed TLSv1.3 ciphersuites. See the ciphers(1ssl) manpage for more
# information about the syntax of this string, and specifically for TLSv1.3
# ciphersuites.
#
# tls-ciphersuites TLS_CHACHA20_POLY1305_SHA256
# When choosing a cipher, use the server's preference instead of the client
# preference. By default, the server follows the client's preference.
#
# tls-prefer-server-ciphers yes
# By default, TLS session caching is enabled to allow faster and less expensive
# reconnections by clients that support it. Use the following directive to disable
# caching.
#
# tls-session-caching no
# Change the default number of TLS sessions cached. A zero value sets the cache
# to unlimited size. The default size is 20480.
#
# tls-session-cache-size 5000
# Change the default timeout of cached TLS sessions. The default timeout is 300
# seconds.
#
# tls-session-cache-timeout 60
################################# GENERAL #####################################
# By default Redis does not run as a daemon. Use 'yes' if you need it.
# Note that Redis will write a pid file in /var/run/redis.pid when daemonized.
# When Redis is supervised by upstart or systemd, this parameter has no impact.
设置后台进程运行模式,yes代表允许后台运行
daemonize yes
# If you run Redis from upstart or systemd, Redis can interact with your
# supervision tree. Options:
# supervised no - no supervision interaction
# supervised upstart - signal upstart by putting Redis into SIGSTOP mode
# requires "expect stop" in your upstart job config
# supervised systemd - signal systemd by writing READY=1 to $NOTIFY_SOCKET
# on startup, and updating Redis status on a regular
# basis.
# supervised auto - detect upstart or systemd method based on
# UPSTART_JOB or NOTIFY_SOCKET environment variables
# Note: these supervision methods only signal "process is ready."
# They do not enable continuous pings back to your supervisor.
#
# The default is "no". To run under upstart/systemd, you can simply uncomment
# the line below:
#
# supervised auto
# If a pid file is specified, Redis writes it where specified at startup
# and removes it at exit.
#
# When the server runs non daemonized, no pid file is created if none is
# specified in the configuration. When the server is daemonized, the pid file
# is used even if not specified, defaulting to "/var/run/redis.pid".
#
# Creating a pid file is best effort: if Redis is not able to create it
# nothing bad happens, the server will start and run normally.
#
# Note that on modern Linux systems "/run/redis.pid" is more conforming
# and should be used instead.
与进程相关的文件
pidfile /var/run/redis_6379.pid
# Specify the server verbosity level.
# This can be one of:
# debug (a lot of information, useful for development/testing)
# verbose (many rarely useful info, but not a mess like the debug level)
# notice (moderately verbose, what you want in production probably)
# warning (only very important / critical messages are logged)
设置日志级别
loglevel notice
# Specify the log file name. Also the empty string can be used to force
# Redis to log on the standard output. Note that if you use standard
# output for logging but daemonize, logs will be sent to /dev/null
日志文件的名字,保存路径为/dev/null/文件
logfile ""
# To enable logging to the system logger, just set 'syslog-enabled' to yes,
# and optionally update the other syslog parameters to suit your needs.
# syslog-enabled no
# Specify the syslog identity.
# syslog-ident redis
# Specify the syslog facility. Must be USER or between LOCAL0-LOCAL7.
# syslog-facility local0
# To disable the built in crash log, which will possibly produce cleaner core
# dumps when they are needed, uncomment the following:
#
# crash-log-enabled no
# To disable the fast memory check that's run as part of the crash log, which
# will possibly let redis terminate sooner, uncomment the following:
#
# crash-memcheck-enabled no
# Set the number of databases. The default database is DB 0, you can select
# a different one on a per-connection basis using SELECT <dbid> where
# dbid is a number between 0 and 'databases'-1
默认的数据库数量
databases 16
# By default Redis shows an ASCII art logo only when started to log to the
# standard output and if the standard output is a TTY and syslog logging is
# disabled. Basically this means that normally a logo is displayed only in
# interactive sessions.
#
# However it is possible to force the pre-4.0 behavior and always show a
# ASCII art logo in startup logs by setting the following option to yes.
redis服务端启动时的logo显示设置
always-show-logo no
# By default, Redis modifies the process title (as seen in 'top' and 'ps') to
# provide some runtime information. It is possible to disable this and leave
# the process name as executed by setting the following to no.
set-proc-title yes
# When changing the process title, Redis uses the following template to construct
# the modified title.
#
# Template variables are specified in curly brackets. The following variables are
# supported:
#
# {title} Name of process as executed if parent, or type of child process.
# {listen-addr} Bind address or '*' followed by TCP or TLS port listening on, or
# Unix socket if only that's available.
# {server-mode} Special mode, i.e. "[sentinel]" or "[cluster]".
# {port} TCP port listening on, or 0.
# {tls-port} TLS port listening on, or 0.
# {unixsocket} Unix domain socket listening on, or "".
# {config-file} Name of configuration file used.
#
proc-title-template "{title} {listen-addr} {server-mode}"
################################ SNAPSHOTTING ################################
# Save the DB to disk.
#
# save <seconds> <changes>
#
# Redis will save the DB if both the given number of seconds and the given
# number of write operations against the DB occurred.
#
# Snapshotting can be completely disabled with a single empty string argument
# as in following example:
#
# save ""
#
# Unless specified otherwise, by default Redis will save the DB:
# * After 3600 seconds (an hour) if at least 1 key changed
# * After 300 seconds (5 minutes) if at least 100 keys changed
# * After 60 seconds if at least 10000 keys changed
#
# You can set these explicitly by uncommenting the three following lines.
#
持久化时的设置
以下三个意思:
在3600秒内,如果key改变1次,则持久化
在300 秒内,如果key改变100次,则持久化
在60 秒内,如果key改变10000次,则持久化
# save 3600 1
# save 300 100
# save 60 10000
# By default Redis will stop accepting writes if RDB snapshots are enabled
# (at least one save point) and the latest background save failed.
# This will make the user aware (in a hard way) that data is not persisting
# on disk properly, otherwise chances are that no one will notice and some
# disaster will happen.
#
# If the background saving process will start working again Redis will
# automatically allow writes again.
#
# However if you have setup your proper monitoring of the Redis server
# and persistence, you may want to disable this feature so that Redis will
# continue to work as usual even if there are problems with disk,
# permissions, and so forth.
持久化出现错误时,是否停止
stop-writes-on-bgsave-error yes
# Compress string objects using LZF when dump .rdb databases?
# By default compression is enabled as it's almost always a win.
# If you want to save some CPU in the saving child set it to 'no' but
# the dataset will likely be bigger if you have compressible values or keys.
持久化时的rdb是否压缩
rdbcompression yes
# Since version 5 of RDB a CRC64 checksum is placed at the end of the file.
# This makes the format more resistant to corruption but there is a performance
# hit to pay (around 10%) when saving and loading RDB files, so you can disable it
# for maximum performances.
#
# RDB files created with checksum disabled have a checksum of zero that will
# tell the loading code to skip the check.
是否对持久化后的rdb文件进行检测
rdbchecksum yes
# Enables or disables full sanitation checks for ziplist and listpack etc when
# loading an RDB or RESTORE payload. This reduces the chances of a assertion or
# crash later on while processing commands.
# Options:
# no - Never perform full sanitation
# yes - Always perform full sanitation
# clients - Perform full sanitation only for user connections.
# Excludes: RDB files, RESTORE commands received from the master
# connection, and client connections which have the
# skip-sanitize-payload ACL flag.
# The default should be 'clients' but since it currently affects cluster
# resharding via MIGRATE, it is temporarily set to 'no' by default.
#
# sanitize-dump-payload no
# The filename where to dump the DB
rdb的文件名
dbfilename dump.rdb
# Remove RDB files used by replication in instances without persistence
# enabled. By default this option is disabled, however there are environments
# where for regulations or other security concerns, RDB files persisted on
# disk by masters in order to feed replicas, or stored on disk by replicas
# in order to load them for the initial synchronization, should be deleted
# ASAP. Note that this option ONLY WORKS in instances that have both AOF
# and RDB persistence disabled, otherwise is completely ignored.
#
# An alternative (and sometimes better) way to obtain the same effect is
# to use diskless replication on both master and replicas instances. However
# in the case of replicas, diskless is not always an option.
rdb-del-sync-files no
# The working directory.
#
# The DB will be written inside this directory, with the filename specified
# above using the 'dbfilename' configuration directive.
#
# The Append Only File will also be created inside this directory.
#
# Note that you must specify a directory here, not a file name.
rdb文件的位置
dir ./
主从复制相关
################################# REPLICATION #################################
# Master-Replica replication. Use replicaof to make a Redis instance a copy of
# another Redis server. A few things to understand ASAP about Redis replication.
#
# +------------------+ +---------------+
# | Master | ---> | Replica |
# | (receive writes) | | (exact copy) |
# +------------------+ +---------------+
#
# 1) Redis replication is asynchronous, but you can configure a master to
# stop accepting writes if it appears to be not connected with at least
# a given number of replicas.
# 2) Redis replicas are able to perform a partial resynchronization with the
# master if the replication link is lost for a relatively small amount of
# time. You may want to configure the replication backlog size (see the next
# sections of this file) with a sensible value depending on your needs.
# 3) Replication is automatic and does not need user intervention. After a
# network partition replicas automatically try to reconnect to masters
# and resynchronize with them.
#
# replicaof <masterip> <masterport>
# If the master is password protected (using the "requirepass" configuration
# directive below) it is possible to tell the replica to authenticate before
# starting the replication synchronization process, otherwise the master will
# refuse the replica request.
#
# masterauth <master-password>
#
# However this is not enough if you are using Redis ACLs (for Redis version
# 6 or greater), and the default user is not capable of running the PSYNC
# command and/or other commands needed for replication. In this case it's
# better to configure a special user to use with replication, and specify the
# masteruser configuration as such:
#
# masteruser <username>
#
# When masteruser is specified, the replica will authenticate against its
# master using the new AUTH form: AUTH <username> <password>.
# When a replica loses its connection with the master, or when the replication
# is still in progress, the replica can act in two different ways:
#
# 1) if replica-serve-stale-data is set to 'yes' (the default) the replica will
# still reply to client requests, possibly with out of date data, or the
# data set may just be empty if this is the first synchronization.
#
# 2) If replica-serve-stale-data is set to 'no' the replica will reply with
# an error "SYNC with master in progress" to all commands except:
# INFO, REPLICAOF, AUTH, PING, SHUTDOWN, REPLCONF, ROLE, CONFIG, SUBSCRIBE,
# UNSUBSCRIBE, PSUBSCRIBE, PUNSUBSCRIBE, PUBLISH, PUBSUB, COMMAND, POST,
# HOST and LATENCY.
#
replica-serve-stale-data yes
# You can configure a replica instance to accept writes or not. Writing against
# a replica instance may be useful to store some ephemeral data (because data
# written on a replica will be easily deleted after resync with the master) but
# may also cause problems if clients are writing to it because of a
# misconfiguration.
#
# Since Redis 2.6 by default replicas are read-only.
#
# Note: read only replicas are not designed to be exposed to untrusted clients
# on the internet. It's just a protection layer against misuse of the instance.
# Still a read only replica exports by default all the administrative commands
# such as CONFIG, DEBUG, and so forth. To a limited extent you can improve
# security of read only replicas using 'rename-command' to shadow all the
# administrative / dangerous commands.
replica-read-only yes
# Replication SYNC strategy: disk or socket.
#
# New replicas and reconnecting replicas that are not able to continue the
# replication process just receiving differences, need to do what is called a
# "full synchronization". An RDB file is transmitted from the master to the
# replicas.
#
# The transmission can happen in two different ways:
#
# 1) Disk-backed: The Redis master creates a new process that writes the RDB
# file on disk. Later the file is transferred by the parent
# process to the replicas incrementally.
# 2) Diskless: The Redis master creates a new process that directly writes the
# RDB file to replica sockets, without touching the disk at all.
#
# With disk-backed replication, while the RDB file is generated, more replicas
# can be queued and served with the RDB file as soon as the current child
# producing the RDB file finishes its work. With diskless replication instead
# once the transfer starts, new replicas arriving will be queued and a new
# transfer will start when the current one terminates.
#
# When diskless replication is used, the master waits a configurable amount of
# time (in seconds) before starting the transfer in the hope that multiple
# replicas will arrive and the transfer can be parallelized.
#
# With slow disks and fast (large bandwidth) networks, diskless replication
# works better.
repl-diskless-sync no
# When diskless replication is enabled, it is possible to configure the delay
# the server waits in order to spawn the child that transfers the RDB via socket
# to the replicas.
#
# This is important since once the transfer starts, it is not possible to serve
# new replicas arriving, that will be queued for the next RDB transfer, so the
# server waits a delay in order to let more replicas arrive.
#
# The delay is specified in seconds, and by default is 5 seconds. To disable
# it entirely just set it to 0 seconds and the transfer will start ASAP.
repl-diskless-sync-delay 5
# -----------------------------------------------------------------------------
# WARNING: RDB diskless load is experimental. Since in this setup the replica
# does not immediately store an RDB on disk, it may cause data loss during
# failovers. RDB diskless load + Redis modules not handling I/O reads may also
# cause Redis to abort in case of I/O errors during the initial synchronization
# stage with the master. Use only if you know what you are doing.
# -----------------------------------------------------------------------------
#
# Replica can load the RDB it reads from the replication link directly from the
# socket, or store the RDB to a file and read that file after it was completely
# received from the master.
#
# In many cases the disk is slower than the network, and storing and loading
# the RDB file may increase replication time (and even increase the master's
# Copy on Write memory and salve buffers).
# However, parsing the RDB file directly from the socket may mean that we have
# to flush the contents of the current database before the full rdb was
# received. For this reason we have the following options:
#
# "disabled" - Don't use diskless load (store the rdb file to the disk first)
# "on-empty-db" - Use diskless load only when it is completely safe.
# "swapdb" - Keep a copy of the current db contents in RAM while parsing
# the data directly from the socket. note that this requires
# sufficient memory, if you don't have it, you risk an OOM kill.
repl-diskless-load disabled
# Replicas send PINGs to server in a predefined interval. It's possible to
# change this interval with the repl_ping_replica_period option. The default
# value is 10 seconds.
#
# repl-ping-replica-period 10
# The following option sets the replication timeout for:
#
# 1) Bulk transfer I/O during SYNC, from the point of view of replica.
# 2) Master timeout from the point of view of replicas (data, pings).
# 3) Replica timeout from the point of view of masters (REPLCONF ACK pings).
#
# It is important to make sure that this value is greater than the value
# specified for repl-ping-replica-period otherwise a timeout will be detected
# every time there is low traffic between the master and the replica. The default
# value is 60 seconds.
#
# repl-timeout 60
# Disable TCP_NODELAY on the replica socket after SYNC?
#
# If you select "yes" Redis will use a smaller number of TCP packets and
# less bandwidth to send data to replicas. But this can add a delay for
# the data to appear on the replica side, up to 40 milliseconds with
# Linux kernels using a default configuration.
#
# If you select "no" the delay for data to appear on the replica side will
# be reduced but more bandwidth will be used for replication.
#
# By default we optimize for low latency, but in very high traffic conditions
# or when the master and replicas are many hops away, turning this to "yes" may
# be a good idea.
repl-disable-tcp-nodelay no
# Set the replication backlog size. The backlog is a buffer that accumulates
# replica data when replicas are disconnected for some time, so that when a
# replica wants to reconnect again, often a full resync is not needed, but a
# partial resync is enough, just passing the portion of data the replica
# missed while disconnected.
#
# The bigger the replication backlog, the longer the replica can endure the
# disconnect and later be able to perform a partial resynchronization.
#
# The backlog is only allocated if there is at least one replica connected.
#
# repl-backlog-size 1mb
# After a master has no connected replicas for some time, the backlog will be
# freed. The following option configures the amount of seconds that need to
# elapse, starting from the time the last replica disconnected, for the backlog
# buffer to be freed.
#
# Note that replicas never free the backlog for timeout, since they may be
# promoted to masters later, and should be able to correctly "partially
# resynchronize" with other replicas: hence they should always accumulate backlog.
#
# A value of 0 means to never release the backlog.
#
# repl-backlog-ttl 3600
# The replica priority is an integer number published by Redis in the INFO
# output. It is used by Redis Sentinel in order to select a replica to promote
# into a master if the master is no longer working correctly.
#
# A replica with a low priority number is considered better for promotion, so
# for instance if there are three replicas with priority 10, 100, 25 Sentinel
# will pick the one with priority 10, that is the lowest.
#
# However a special priority of 0 marks the replica as not able to perform the
# role of master, so a replica with priority of 0 will never be selected by
# Redis Sentinel for promotion.
#
# By default the priority is 100.
replica-priority 100
# It is possible for a master to stop accepting writes if there are less than
# N replicas connected, having a lag less or equal than M seconds.
#
# The N replicas need to be in "online" state.
#
# The lag in seconds, that must be <= the specified value, is calculated from
# the last ping received from the replica, that is usually sent every second.
#
# This option does not GUARANTEE that N replicas will accept the write, but
# will limit the window of exposure for lost writes in case not enough replicas
# are available, to the specified number of seconds.
#
# For example to require at least 3 replicas with a lag <= 10 seconds use:
#
# min-replicas-to-write 3
# min-replicas-max-lag 10
#
# Setting one or the other to 0 disables the feature.
#
# By default min-replicas-to-write is set to 0 (feature disabled) and
# min-replicas-max-lag is set to 10.
# A Redis master is able to list the address and port of the attached
# replicas in different ways. For example the "INFO replication" section
# offers this information, which is used, among other tools, by
# Redis Sentinel in order to discover replica instances.
# Another place where this info is available is in the output of the
# "ROLE" command of a master.
#
# The listed IP address and port normally reported by a replica is
# obtained in the following way:
#
# IP: The address is auto detected by checking the peer address
# of the socket used by the replica to connect with the master.
#
# Port: The port is communicated by the replica during the replication
# handshake, and is normally the port that the replica is using to
# listen for connections.
#
# However when port forwarding or Network Address Translation (NAT) is
# used, the replica may actually be reachable via different IP and port
# pairs. The following two options can be used by a replica in order to
# report to its master a specific set of IP and port, so that both INFO
# and ROLE will report those values.
#
# There is no need to use both the options if you need to override just
# the port or the IP address.
#
# replica-announce-ip 5.5.5.5
# replica-announce-port 1234
############################### KEYS TRACKING #################################
# Redis implements server assisted support for client side caching of values.
# This is implemented using an invalidation table that remembers, using
# a radix key indexed by key name, what clients have which keys. In turn
# this is used in order to send invalidation messages to clients. Please
# check this page to understand more about the feature:
#
# https://redis.io/topics/client-side-caching
#
# When tracking is enabled for a client, all the read only queries are assumed
# to be cached: this will force Redis to store information in the invalidation
# table. When keys are modified, such information is flushed away, and
# invalidation messages are sent to the clients. However if the workload is
# heavily dominated by reads, Redis could use more and more memory in order
# to track the keys fetched by many clients.
#
# For this reason it is possible to configure a maximum fill value for the
# invalidation table. By default it is set to 1M of keys, and once this limit
# is reached, Redis will start to evict keys in the invalidation table
# even if they were not modified, just to reclaim memory: this will in turn
# force the clients to invalidate the cached values. Basically the table
# maximum size is a trade off between the memory you want to spend server
# side to track information about who cached what, and the ability of clients
# to retain cached objects in memory.
#
# If you set the value to 0, it means there are no limits, and Redis will
# retain as many keys as needed in the invalidation table.
# In the "stats" INFO section, you can find information about the number of
# keys in the invalidation table at every given moment.
#
# Note: when key tracking is used in broadcasting mode, no memory is used
# in the server side so this setting is useless.
#
# tracking-table-max-keys 1000000
################################## SECURITY ###################################
# Warning: since Redis is pretty fast, an outside user can try up to
# 1 million passwords per second against a modern box. This means that you
# should use very strong passwords, otherwise they will be very easy to break.
# Note that because the password is really a shared secret between the client
# and the server, and should not be memorized by any human, the password
# can be easily a long string from /dev/urandom or whatever, so by using a
# long and unguessable password no brute force attack will be possible.
# Redis ACL users are defined in the following format:
#
# user <username> ... acl rules ...
#
# For example:
#
# user worker +@list +@connection ~jobs:* on >ffa9203c493aa99
#
# The special username "default" is used for new connections. If this user
# has the "nopass" rule, then new connections will be immediately authenticated
# as the "default" user without the need of any password provided via the
# AUTH command. Otherwise if the "default" user is not flagged with "nopass"
# the connections will start in not authenticated state, and will require
# AUTH (or the HELLO command AUTH option) in order to be authenticated and
# start to work.
#
# The ACL rules that describe what a user can do are the following:
#
# on Enable the user: it is possible to authenticate as this user.
# off Disable the user: it's no longer possible to authenticate
# with this user, however the already authenticated connections
# will still work.
# skip-sanitize-payload RESTORE dump-payload sanitation is skipped.
# sanitize-payload RESTORE dump-payload is sanitized (default).
# +<command> Allow the execution of that command
# -<command> Disallow the execution of that command
# +@<category> Allow the execution of all the commands in such category
# with valid categories are like @admin, @set, @sortedset, ...
# and so forth, see the full list in the server.c file where
# the Redis command table is described and defined.
# The special category @all means all the commands, but currently
# present in the server, and that will be loaded in the future
# via modules.
# +<command>|subcommand Allow a specific subcommand of an otherwise
# disabled command. Note that this form is not
# allowed as negative like -DEBUG|SEGFAULT, but
# only additive starting with "+".
# allcommands Alias for +@all. Note that it implies the ability to execute
# all the future commands loaded via the modules system.
# nocommands Alias for -@all.
# ~<pattern> Add a pattern of keys that can be mentioned as part of
# commands. For instance ~* allows all the keys. The pattern
# is a glob-style pattern like the one of KEYS.
# It is possible to specify multiple patterns.
# allkeys Alias for ~*
# resetkeys Flush the list of allowed keys patterns.
# &<pattern> Add a glob-style pattern of Pub/Sub channels that can be
# accessed by the user. It is possible to specify multiple channel
# patterns.
# allchannels Alias for &*
# resetchannels Flush the list of allowed channel patterns.
# ><password> Add this password to the list of valid password for the user.
# For example >mypass will add "mypass" to the list.
# This directive clears the "nopass" flag (see later).
# <<password> Remove this password from the list of valid passwords.
# nopass All the set passwords of the user are removed, and the user
# is flagged as requiring no password: it means that every
# password will work against this user. If this directive is
# used for the default user, every new connection will be
# immediately authenticated with the default user without
# any explicit AUTH command required. Note that the "resetpass"
# directive will clear this condition.
# resetpass Flush the list of allowed passwords. Moreover removes the
# "nopass" status. After "resetpass" the user has no associated
# passwords and there is no way to authenticate without adding
# some password (or setting it as "nopass" later).
# reset Performs the following actions: resetpass, resetkeys, off,
# -@all. The user returns to the same state it has immediately
# after its creation.
#
# ACL rules can be specified in any order: for instance you can start with
# passwords, then flags, or key patterns. However note that the additive
# and subtractive rules will CHANGE MEANING depending on the ordering.
# For instance see the following example:
#
# user alice on +@all -DEBUG ~* >somepassword
#
# This will allow "alice" to use all the commands with the exception of the
# DEBUG command, since +@all added all the commands to the set of the commands
# alice can use, and later DEBUG was removed. However if we invert the order
# of two ACL rules the result will be different:
#
# user alice on -DEBUG +@all ~* >somepassword
#
# Now DEBUG was removed when alice had yet no commands in the set of allowed
# commands, later all the commands are added, so the user will be able to
# execute everything.
#
# Basically ACL rules are processed left-to-right.
#
# For more information about ACL configuration please refer to
# the Redis web site at https://redis.io/topics/acl
# ACL LOG
#
# The ACL Log tracks failed commands and authentication events associated
# with ACLs. The ACL Log is useful to troubleshoot failed commands blocked
# by ACLs. The ACL Log is stored in memory. You can reclaim memory with
# ACL LOG RESET. Define the maximum entry length of the ACL Log below.
acllog-max-len 128
# Using an external ACL file
#
# Instead of configuring users here in this file, it is possible to use
# a stand-alone file just listing users. The two methods cannot be mixed:
# if you configure users here and at the same time you activate the external
# ACL file, the server will refuse to start.
#
# The format of the external ACL user file is exactly the same as the
# format that is used inside redis.conf to describe users.
#
# aclfile /etc/redis/users.acl
# IMPORTANT NOTE: starting with Redis 6 "requirepass" is just a compatibility
# layer on top of the new ACL system. The option effect will be just setting
# the password for the default user. Clients will still authenticate using
# AUTH <password> as usually, or more explicitly with AUTH default <password>
# if they follow the new protocol: both will work.
#
# The requirepass is not compatable with aclfile option and the ACL LOAD
# command, these will cause requirepass to be ignored.
# requirepass fooba
设置密码
requirepass 123456
# New users are initialized with restrictive permissions by default, via the
# equivalent of this ACL rule 'off resetkeys -@all'. Starting with Redis 6.2, it
# is possible to manage access to Pub/Sub channels with ACL rules as well. The
# default Pub/Sub channels permission if new users is controlled by the
# acl-pubsub-default configuration directive, which accepts one of these values:
#
# allchannels: grants access to all Pub/Sub channels
# resetchannels: revokes access to all Pub/Sub channels
#
# To ensure backward compatibility while upgrading Redis 6.0, acl-pubsub-default
# defaults to the 'allchannels' permission.
#
# Future compatibility note: it is very likely that in a future version of Redis
# the directive's default of 'allchannels' will be changed to 'resetchannels' in
# order to provide better out-of-the-box Pub/Sub security. Therefore, it is
# recommended that you explicitly define Pub/Sub permissions for all users
# rather then rely on implicit default values. Once you've set explicit
# Pub/Sub for all exisitn users, you should uncomment the following line.
#
# acl-pubsub-default resetchannels
# Command renaming (DEPRECATED).
#
# ------------------------------------------------------------------------
# WARNING: avoid using this option if possible. Instead use ACLs to remove
# commands from the default user, and put them only in some admin user you
# create for administrative purposes.
# ------------------------------------------------------------------------
#
# It is possible to change the name of dangerous commands in a shared
# environment. For instance the CONFIG command may be renamed into something
# hard to guess so that it will still be available for internal-use tools
# but not available for general clients.
#
# Example:
#
# rename-command CONFIG b840fc02d524045429941cc15f59e41cb7be6c52
#
# It is also possible to completely kill a command by renaming it into
# an empty string:
#
# rename-command CONFIG ""
#
# Please note that changing the name of commands that are logged into the
# AOF file or transmitted to replicas may cause problems.
################################### CLIENTS ####################################
# Set the max number of connected clients at the same time. By default
# this limit is set to 10000 clients, however if the Redis server is not
# able to configure the process file limit to allow for the specified limit
# the max number of allowed clients is set to the current file limit
# minus 32 (as Redis reserves a few file descriptors for internal uses).
#
# Once the limit is reached Redis will close all the new connections sending
# an error 'max number of clients reached'.
#
# IMPORTANT: When Redis Cluster is used, the max number of connections is also
# shared with the cluster bus: every node in the cluster will use two
# connections, one incoming and another outgoing. It is important to size the
# limit accordingly in case of very large clusters.
#
最大可连接的客户端数量
# maxclients 10000
############################## MEMORY MANAGEMENT ################################
# Set a memory usage limit to the specified amount of bytes.
# When the memory limit is reached Redis will try to remove keys
# according to the eviction policy selected (see maxmemory-policy).
#
# If Redis can't remove keys according to the policy, or if the policy is
# set to 'noeviction', Redis will start to reply with errors to commands
# that would use more memory, like SET, LPUSH, and so on, and will continue
# to reply to read-only commands like GET.
#
# This option is usually useful when using Redis as an LRU or LFU cache, or to
# set a hard memory limit for an instance (using the 'noeviction' policy).
#
# WARNING: If you have replicas attached to an instance with maxmemory on,
# the size of the output buffers needed to feed the replicas are subtracted
# from the used memory count, so that network problems / resyncs will
# not trigger a loop where keys are evicted, and in turn the output
# buffer of replicas is full with DELs of keys evicted triggering the deletion
# of more keys, and so forth until the database is completely emptied.
#
# In short... if you have replicas attached it is suggested that you set a lower
# limit for maxmemory so that there is some free RAM on the system for replica
# output buffers (but this is not needed if the policy is 'noeviction').
#
设置最大的内存
# maxmemory <bytes>
# MAXMEMORY POLICY: how Redis will select what to remove when maxmemory
# is reached. You can select one from the following behaviors:
#
# volatile-lru -> Evict using approximated LRU, only keys with an expire set.
# allkeys-lru -> Evict any key using approximated LRU.
# volatile-lfu -> Evict using approximated LFU, only keys with an expire set.
# allkeys-lfu -> Evict any key using approximated LFU.
# volatile-random -> Remove a random key having an expire set.
# allkeys-random -> Remove a random key, any key.
# volatile-ttl -> Remove the key with the nearest expire time (minor TTL)
# noeviction -> Don't evict anything, just return an error on write operations.
#
# LRU means Least Recently Used
# LFU means Least Frequently Used
#
# Both LRU, LFU and volatile-ttl are implemented using approximated
# randomized algorithms.
#
# Note: with any of the above policies, when there are no suitable keys for
# eviction, Redis will return an error on write operations that require
# more memory. These are usually commands that create new keys, add data or
# modify existing keys. A few examples are: SET, INCR, HSET, LPUSH, SUNIONSTORE,
# SORT (due to the STORE argument), and EXEC (if the transaction includes any
# command that requires memory).
#
# The default is:
#
内存溢出时的处理策略
# maxmemory-policy noeviction
# LRU, LFU and minimal TTL algorithms are not precise algorithms but approximated
# algorithms (in order to save memory), so you can tune it for speed or
# accuracy. By default Redis will check five keys and pick the one that was
# used least recently, you can change the sample size using the following
# configuration directive.
#
# The default of 5 produces good enough results. 10 Approximates very closely
# true LRU but costs more CPU. 3 is faster but not very accurate.
#
# maxmemory-samples 5
# Eviction processing is designed to function well with the default setting.
# If there is an unusually large amount of write traffic, this value may need to
# be increased. Decreasing this value may reduce latency at the risk of
# eviction processing effectiveness
# 0 = minimum latency, 10 = default, 100 = process without regard to latency
#
# maxmemory-eviction-tenacity 10
# Starting from Redis 5, by default a replica will ignore its maxmemory setting
# (unless it is promoted to master after a failover or manually). It means
# that the eviction of keys will be just handled by the master, sending the
# DEL commands to the replica as keys evict in the master side.
#
# This behavior ensures that masters and replicas stay consistent, and is usually
# what you want, however if your replica is writable, or you want the replica
# to have a different memory setting, and you are sure all the writes performed
# to the replica are idempotent, then you may change this default (but be sure
# to understand what you are doing).
#
# Note that since the replica by default does not evict, it may end using more
# memory than the one set via maxmemory (there are certain buffers that may
# be larger on the replica, or data structures may sometimes take more memory
# and so forth). So make sure you monitor your replicas and make sure they
# have enough memory to never hit a real out-of-memory condition before the
# master hits the configured maxmemory setting.
#
# replica-ignore-maxmemory yes
# Redis reclaims expired keys in two ways: upon access when those keys are
# found to be expired, and also in background, in what is called the
# "active expire key". The key space is slowly and interactively scanned
# looking for expired keys to reclaim, so that it is possible to free memory
# of keys that are expired and will never be accessed again in a short time.
#
# The default effort of the expire cycle will try to avoid having more than
# ten percent of expired keys still in memory, and will try to avoid consuming
# more than 25% of total memory and to add latency to the system. However
# it is possible to increase the expire "effort" that is normally set to
# "1", to a greater value, up to the value "10". At its maximum value the
# system will use more CPU, longer cycles (and technically may introduce
# more latency), and will tolerate less already expired keys still present
# in the system. It's a tradeoff between memory, CPU and latency.
#
# active-expire-effort 1
############################# LAZY FREEING ####################################
# Redis has two primitives to delete keys. One is called DEL and is a blocking
# deletion of the object. It means that the server stops processing new commands
# in order to reclaim all the memory associated with an object in a synchronous
# way. If the key deleted is associated with a small object, the time needed
# in order to execute the DEL command is very small and comparable to most other
# O(1) or O(log_N) commands in Redis. However if the key is associated with an
# aggregated value containing millions of elements, the server can block for
# a long time (even seconds) in order to complete the operation.
#
# For the above reasons Redis also offers non blocking deletion primitives
# such as UNLINK (non blocking DEL) and the ASYNC option of FLUSHALL and
# FLUSHDB commands, in order to reclaim memory in background. Those commands
# are executed in constant time. Another thread will incrementally free the
# object in the background as fast as possible.
#
# DEL, UNLINK and ASYNC option of FLUSHALL and FLUSHDB are user-controlled.
# It's up to the design of the application to understand when it is a good
# idea to use one or the other. However the Redis server sometimes has to
# delete keys or flush the whole database as a side effect of other operations.
# Specifically Redis deletes objects independently of a user call in the
# following scenarios:
#
# 1) On eviction, because of the maxmemory and maxmemory policy configurations,
# in order to make room for new data, without going over the specified
# memory limit.
# 2) Because of expire: when a key with an associated time to live (see the
# EXPIRE command) must be deleted from memory.
# 3) Because of a side effect of a command that stores data on a key that may
# already exist. For example the RENAME command may delete the old key
# content when it is replaced with another one. Similarly SUNIONSTORE
# or SORT with STORE option may delete existing keys. The SET command
# itself removes any old content of the specified key in order to replace
# it with the specified string.
# 4) During replication, when a replica performs a full resynchronization with
# its master, the content of the whole database is removed in order to
# load the RDB file just transferred.
#
# In all the above cases the default is to delete objects in a blocking way,
# like if DEL was called. However you can configure each case specifically
# in order to instead release memory in a non-blocking way like if UNLINK
# was called, using the following configuration directives.
lazyfree-lazy-eviction no
lazyfree-lazy-expire no
lazyfree-lazy-server-del no
replica-lazy-flush no
# It is also possible, for the case when to replace the user code DEL calls
# with UNLINK calls is not easy, to modify the default behavior of the DEL
# command to act exactly like UNLINK, using the following configuration
# directive:
lazyfree-lazy-user-del no
# FLUSHDB, FLUSHALL, and SCRIPT FLUSH support both asynchronous and synchronous
# deletion, which can be controlled by passing the [SYNC|ASYNC] flags into the
# commands. When neither flag is passed, this directive will be used to determine
# if the data should be deleted asynchronously.
lazyfree-lazy-user-flush no
################################ THREADED I/O #################################
# Redis is mostly single threaded, however there are certain threaded
# operations such as UNLINK, slow I/O accesses and other things that are
# performed on side threads.
#
# Now it is also possible to handle Redis clients socket reads and writes
# in different I/O threads. Since especially writing is so slow, normally
# Redis users use pipelining in order to speed up the Redis performances per
# core, and spawn multiple instances in order to scale more. Using I/O
# threads it is possible to easily speedup two times Redis without resorting
# to pipelining nor sharding of the instance.
#
# By default threading is disabled, we suggest enabling it only in machines
# that have at least 4 or more cores, leaving at least one spare core.
# Using more than 8 threads is unlikely to help much. We also recommend using
# threaded I/O only if you actually have performance problems, with Redis
# instances being able to use a quite big percentage of CPU time, otherwise
# there is no point in using this feature.
#
# So for instance if you have a four cores boxes, try to use 2 or 3 I/O
# threads, if you have a 8 cores, try to use 6 threads. In order to
# enable I/O threads use the following configuration directive:
#
# io-threads 4
#
# Setting io-threads to 1 will just use the main thread as usual.
# When I/O threads are enabled, we only use threads for writes, that is
# to thread the write(2) syscall and transfer the client buffers to the
# socket. However it is also possible to enable threading of reads and
# protocol parsing using the following configuration directive, by setting
# it to yes:
#
# io-threads-do-reads no
#
# Usually threading reads doesn't help much.
#
# NOTE 1: This configuration directive cannot be changed at runtime via
# CONFIG SET. Aso this feature currently does not work when SSL is
# enabled.
#
# NOTE 2: If you want to test the Redis speedup using redis-benchmark, make
# sure you also run the benchmark itself in threaded mode, using the
# --threads option to match the number of Redis threads, otherwise you'll not
# be able to notice the improvements.
############################ KERNEL OOM CONTROL ##############################
# On Linux, it is possible to hint the kernel OOM killer on what processes
# should be killed first when out of memory.
#
# Enabling this feature makes Redis actively control the oom_score_adj value
# for all its processes, depending on their role. The default scores will
# attempt to have background child processes killed before all others, and
# replicas killed before masters.
#
# Redis supports three options:
#
# no: Don't make changes to oom-score-adj (default).
# yes: Alias to "relative" see below.
# absolute: Values in oom-score-adj-values are written as is to the kernel.
# relative: Values are used relative to the initial value of oom_score_adj when
# the server starts and are then clamped to a range of -1000 to 1000.
# Because typically the initial value is 0, they will often match the
# absolute values.
oom-score-adj no
# When oom-score-adj is used, this directive controls the specific values used
# for master, replica and background child processes. Values range -2000 to
# 2000 (higher means more likely to be killed).
#
# Unprivileged processes (not root, and without CAP_SYS_RESOURCE capabilities)
# can freely increase their value, but not decrease it below its initial
# settings. This means that setting oom-score-adj to "relative" and setting the
# oom-score-adj-values to positive values will always succeed.
oom-score-adj-values 0 200 800
#################### KERNEL transparent hugepage CONTROL ######################
# Usually the kernel Transparent Huge Pages control is set to "madvise" or
# or "never" by default (/sys/kernel/mm/transparent_hugepage/enabled), in which
# case this config has no effect. On systems in which it is set to "always",
# redis will attempt to disable it specifically for the redis process in order
# to avoid latency problems specifically with fork(2) and CoW.
# If for some reason you prefer to keep it enabled, you can set this config to
# "no" and the kernel global to "always".
disable-thp yes
aof模式相关
############################## APPEND ONLY MODE ###############################
# By default Redis asynchronously dumps the dataset on disk. This mode is
# good enough in many applications, but an issue with the Redis process or
# a power outage may result into a few minutes of writes lost (depending on
# the configured save points).
#
# The Append Only File is an alternative persistence mode that provides
# much better durability. For instance using the default data fsync policy
# (see later in the config file) Redis can lose just one second of writes in a
# dramatic event like a server power outage, or a single write if something
# wrong with the Redis process itself happens, but the operating system is
# still running correctly.
#
# AOF and RDB persistence can be enabled at the same time without problems.
# If the AOF is enabled on startup Redis will load the AOF, that is the file
# with the better durability guarantees.
#
# Please check http://redis.io/topics/persistence for more information.
启用与否。默认不启用aof模式,默认是使用rdb模式持久化的,在
大部分的情况下,rdb完全够用
appendonly no
# The name of the append only file (default: "appendonly.aof")
保存的文件名
appendfilename "appendonly.aof"
# The fsync() call tells the Operating System to actually write data on disk
# instead of waiting for more data in the output buffer. Some OS will really flush
# data on disk, some other OS will just try to do it ASAP.
#
# Redis supports three different modes:
#
# no: don't fsync, just let the OS flush the data when it wants. Faster.
# always: fsync after every write to the append only log. Slow, Safest.
# everysec: fsync only one time every second. Compromise.
#
# The default is "everysec", as that's usually the right compromise between
# speed and data safety. It's up to you to understand if you can relax this to
# "no" that will let the operating system flush the output buffer when
# it wants, for better performances (but if you can live with the idea of
# some data loss consider the default persistence mode that's snapshotting),
# or on the contrary, use "always" that's very slow but a bit safer than
# everysec.
#
# More details please check the following article:
# http://antirez/post/redis-persistence-demystified.html
#
# If unsure, use "everysec".
每次修改都会sync, 消耗性能
# appendfsync always
第秒执行一次sync,可能会丢失这1秒内的数据(比如说在1秒间隔中,突然出现宕机)
appendfsync everysec
不执行sync,这个时候操作系统自己同步数据,速度最快
# appendfsync no
# When the AOF fsync policy is set to always or everysec, and a background
# saving process (a background save or AOF log background rewriting) is
# performing a lot of I/O against the disk, in some Linux configurations
# Redis may block too long on the fsync() call. Note that there is no fix for
# this currently, as even performing fsync in a different thread will block
# our synchronous write(2) call.
#
# In order to mitigate this problem it's possible to use the following option
# that will prevent fsync() from being called in the main process while a
# BGSAVE or BGREWRITEAOF is in progress.
#
# This means that while another child is saving, the durability of Redis is
# the same as "appendfsync none". In practical terms, this means that it is
# possible to lose up to 30 seconds of log in the worst scenario (with the
# default Linux settings).
#
# If you have latency problems turn this to "yes". Otherwise leave it as
# "no" that is the safest pick from the point of view of durability.
no-appendfsync-on-rewrite no
# Automatic rewrite of the append only file.
# Redis is able to automatically rewrite the log file implicitly calling
# BGREWRITEAOF when the AOF log size grows by the specified percentage.
#
# This is how it works: Redis remembers the size of the AOF file after the
# latest rewrite (if no rewrite has happened since the restart, the size of
# the AOF at startup is used).
#
# This base size is compared to the current size. If the current size is
# bigger than the specified percentage, the rewrite is triggered. Also
# you need to specify a minimal size for the AOF file to be rewritten, this
# is useful to avoid rewriting the AOF file even if the percentage increase
# is reached but it is still pretty small.
#
# Specify a percentage of zero in order to disable the automatic AOF
# rewrite feature.
配置重写的规则。aof文件达到100%或者达到64mb那么会进行重写
auto-aof-rewrite-percentage 100
auto-aof-rewrite-min-size 64mb
# An AOF file may be found to be truncated at the end during the Redis
# startup process, when the AOF data gets loaded back into memory.
# This may happen when the system where Redis is running
# crashes, especially when an ext4 filesystem is mounted without the
# data=ordered option (however this can't happen when Redis itself
# crashes or aborts but the operating system still works correctly).
#
# Redis can either exit with an error when this happens, or load as much
# data as possible (the default now) and start if the AOF file is found
# to be truncated at the end. The following option controls this behavior.
#
# If aof-load-truncated is set to yes, a truncated AOF file is loaded and
# the Redis server starts emitting a log to inform the user of the event.
# Otherwise if the option is set to no, the server aborts with an error
# and refuses to start. When the option is set to no, the user requires
# to fix the AOF file using the "redis-check-aof" utility before to restart
# the server.
#
# Note that if the AOF file will be found to be corrupted in the middle
# the server will still exit with an error. This option only applies when
# Redis will try to read more data from the AOF file but not enough bytes
# will be found.
aof-load-truncated yes
# When rewriting the AOF file, Redis is able to use an RDB preamble in the
# AOF file for faster rewrites and recoveries. When this option is turned
# on the rewritten AOF file is composed of two different stanzas:
#
# [RDB file][AOF tail]
#
# When loading, Redis recognizes that the AOF file starts with the "REDIS"
# string and loads the prefixed RDB file, then continues loading the AOF
# tail.
aof-use-rdb-preamble yes
下面还有配置内容,不过不常用,就不写了!!!!!!!!!!!!!!!!!!!!!!!!!!!!
七、持久化
1、rdb
rdb = redis database
基本原理图
基本特点:
- 在指定时间间隔内将内存中的数据集快照(dump.rdb文件)写入磁盘,即备份
- 恢复时,将快照文件读到内存中去
- 会单独创建一个子进程来进行持久化(相当于开了另外一个软件)
- 主进程不进行持久化工作,因此效率极高
优点:
- 可处理的数据量极大
- 效率高,主进程仍然做自己的工作
- 对数据的完整性要求不高(使用的要求之一)
缺点:
- 要在一定的时间间隔内操作,如果在一定时间内宕机,那么数据存在丢失的可能性
- fork一个子进程,占用资源高
配置文件
- dump.rdb文件是默认保存在redis的启动目录下(启动目录是在你用redis-server 目录/redis.conf时,的目录下。如配置文件位置:bin/myConifg/reids.conf, 如果在bin目录下执行redis-server myConfig/redis.conf, 那么启动目录就是bin目录。如果在myConfig目录下执行redis-server,那么启动目录就是myConfig目录)。
config get dir
可看redis的启动目录- 当redis重启的时候,会自动地将启动目录下的dump.rdb文件读取到内存中
在第六大点中,可以看到这样一个规则:
在3600秒内,如果key改变1次,则持久化
在300 秒内,如果key改变100次,则持久化
在60 秒内,如果key改变10000次,则持久化
# save 3600 1
# save 300 100
# save 60 10000
触发时机
- 满足save规则时
- 执行flushall 或 flushdb(这个不会!)命令时(实践证明:保存的rdb文件中是空的!)
- 退出redis时
2、aof
aof = appedn only file
原理图
基本
- 以日志的形式记录每个写操作
- 每次都会追加文件
- redis启动时,会根据日志文件的内容从头到尾执行一遍
配置文件
- 在启动目录下会生成一个appendonly.aof文件
启用与否。默认不启用aof模式,默认是使用rdb模式持久化的,在
大部分的情况下,rdb完全够用
appendonly no
appendfilename "appendonly.aof"
sync就是write一次
每次修改都会sync, 消耗性能。但文件的完整性会更好
# appendfsync always
第秒执行一次sync,可能会丢失这1秒内的数据(比如说在1秒间隔中,突然出现宕机)
appendfsync everysec
不执行sync,这个时候操作系统自己调度,速度最快
# appendfsync no
重写的配置。
重写是指当aof文件追加满了之后,是否再开启另外一个文件
默认是无限追加!
no-appendfsync-on-rewrite no
如果上面是no,那么下面就无效了
配置重写的规则。aof文件达到100%或者达到64mb那么会进行重写
auto-aof-rewrite-percentage 100
auto-aof-rewrite-min-size 64mb
修复操作
-
在与appendonly.aof同级目录下,会有一个叫redis-check-aof的可执行文件。
-
如果aof文件遭到破坏,redis是启动不起来的!
-
那么用
redis-check-aof --fix apppendonly.alf
命令,可以修复文件。
缺点
- 相对于数据文件rdb来说,占用空间大
- aof运行效率比rdb慢,所以默认配置的rdb
3、rdb与aof相比
-
RDB 持久化方式能够在指定的时间间隔内对你的数据进行快照存储
-
AOF 持久化方式记录每次对服务器写的操作,当服务器重启的时候会重新执行这些命令来恢复原始的数据。AOF命令以Redis 协议追加保存每次写的操作到文件末尾,Redis还能对AOF文件进行后台重写,使得AOF文件的体积不至于过大。
-
只做缓存,如果你只希望你的数据在服务器运行的时候存在,你也可以不使用任何持久化
-
同时开启两种持久化方式
在这种情况下,当redis重启的时候会优先载入AOF文件来恢复原始的数据,因为在通常情况下AOF文件保存的数据集要比RDB文件保存的数据集要完整。RDB 的数据不实时,同时使用两者时服务器重启也只会找AOF文件,那要不要只使用AOF呢?作者建议不要,因为RDB更适合用于备份数据库(AOF在不断变化不好备份),快速重启,而且不会有AOF可能潜在的Bug,留着作为一个万一的手段。 -
性能建议
因为RDB文件只用作后备用途,建议只在Slave上持久化RDB文件,而且只要15分钟备份一次就够了,只保留 save 900 1 这条规则。
如果启用 AOF ,好处是在最恶劣情况下也只会丢失不超过两秒数据,启动脚本较简单只load自己的AOF文件就可以了,代价一是带来了持续的IO,二是AOF rewrite 的最后将 rewrite 过程中产生的新数据写到新文件造成的阻塞几乎是不可避免的。只要硬盘许可,应该尽量减少AOF rewrite的频率,AOF重写的基础大小默认值64M太小了,可以设到5G以上,默认超过原大小100%大小重写可以改到适当的数值。
如果不启用 AOF ,仅靠 Master-Slave Repllcation 实现高可用性也可以,能省掉一大笔IO,也减少了rewrite时带来的系统波动。代价是如果Master/Slave 同时宕掉,会丢失十几分钟的数据,启动脚本也要比较两个 Master/Slave 中的 RDB文件,载入较新的那个,微博就是这种架构。
八、订阅发布
命令
订阅者:
127.0.0.1:6379> SUBSCRIBE hao
Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "hao"
3) (integer) 1
等待消息
1) "message" 说明是一个消息
2) "hao" 消息频道来源
3) "hello,my friends" 消息内容
发布者:
127.0.0.1:6379> PUBLISH hao "hello,my friends"
(integer) 1
127.0.0.1:6379>
原理
- 底层原理上,维护了一个字典(哈希表)。频道作为键,而值是一个链表,链表的结点是订阅该频道的人
- 当进行发布时,会找到对应频道的键,然后遍历链表,把消息传给每一个人
- 当进行订阅时,会自动把自己加入到链表中去
应用
- 实时消息系统
- 实时聊天系统(将一个聊天室作为一个频道,然后所有人即是发布者,又是订阅者)
- 订阅,关注
九、集群
1、环境搭建
修改配置文件即可模拟多服务端:
- 修改端口 port 6379
- 修改进程文件 pidfile /var/run/redis_6379.pid
- 修改日志文件 logfile “6379.log”
- 修改rdb文件 dbfilename dump6379.rdb
- 多窗口开Linux,然后复制多份redis.conf文件,修改上述配置,分别启动配置文件即可
2、主从复制
概念
- 主从复制:将一台Redis服务器(主节点master/leadeer)的数据,复制到其他的Redis服务器(从节点slave/follower)。
- 数据的复制是单向的,只能从主节点到从节点
- Master以写为主,Slave以读为主
- 作用(在操作系统知识可知道,减少错误率的有效方法就是冗余)
- 数据冗余:进行了数据备份
- 服务冗余:一个服务器死掉,还有其他服务器
- 负载均衡
- 高可用:减少停工时间,而保持其服务的高度可用性
- 两种复制
- 全量复制(同步一次性复制):在从机重新的时候,主机会把所有的数据传送给从机
- 增量复制:在全量复制之后的数据操作,都会通过增量复制
- 主机能读能写,但从机只能读,写会报错
命令
info replication
查看当前主机主从相关信息slaveOf 主机名 端口号
让当前主机成为指定主机的从机。注意,命令行方式是临时的,重启后就会变成主机。要永久生效,改配置文件。
配置
指定要成为谁的从机
replicaof <masterip> <masterport>
如果主机设置了密码,则在从机的配置中设置要连接的主机密码
masterauth <master-password>
3、手动配置主机
主从的两个模式
- 改变从机身份:
slaveOf no one
- 在模式二中,如果改变从机1的身份为主机,那么从机1就会变成真正意义上的主机。
4、哨兵模式
目前没用到,了解基本概念即可,以后要用才继续学习。
- 一种监测机制,在主机宕机后可以自动选出新主机
- 两种分类:
- 单哨兵:由一个机器当哨兵
- 多哨兵:哨兵监测多个主从机,哨兵之间也会互相监测
- 主观下线:一个哨兵认为主机宕机了
- 客观下线:发起投票后,通过了主机宕机的意见
- 基本配置:
sentinel monitor 为监测的主机起名 主机端口 1(代表投票机制)
,命名为sentinel.conf文件。启动:redis-sentinel sentinel.conf
十、缓存相关问题
涉及到高可用方面的问题。
- 缓存穿透:客户端多次请求一个缓存和持久化数据库中都不存在的数据,请求绕过缓存,每次都直接发请求给持久化数据库
- 缓存击穿:对一个热点的key大量访问,当key失效的一瞬间,大量的请求直接发送到持久化数据库中,导致宕机
- 缓存雪崩:一段时间内,大量的缓存同时失效,多种不同请求直接发送给持久化数据库
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