【Redis】基础1：基本概念，基本数据结构-优快云博客

1. 一些概念

1.1 NoSQL

NoSQL数据库：Not Only SQL。非传统关系型数据库。特点：数据模型灵活，可扩展性高（设计为分布式），高性能（内存存储，数据结构和算法高效），高可用（数据复制，分片等）。适用场景：实时数据分析，大数据存储和分析（分布式），内容系统（文档型数据库），社交网络和推荐系统（图数据库）

NoSQL数据库的类型

键值对：Redis，Mencache
文档型：MongoDB，ES
列式存储数据库：Cassandra，Clickhouse，HBase
图数据库：Neo4j

1.2 OLTP与OLAP

在线事务处理（OLTP）：面向交易的处理系统，它是一种对数据库进行实时读写操作的系统，主要用于处理日常的业务交易。如MySQL（关系型），OceanBase（分布式数据库），Redis（内存数据库）

在线分析处理（OLAP）：用于支持复杂分析和决策制定的系统，它主要对大量的历史数据进行汇总、分析和挖掘。如SSAS（关系型），EssBase（多为数据库），Clinckhouse（列式存储）。

1.3 Redis特点

AICD支持：redis所有操作是原子的，支持持久化。

数据丰富：值类型：string，list，set，sortedset，hash，sorted hash，Bitmaps，HyperLogLogs，Geospatial，Pub/Sub，Streams，Modules。

性能：支持每秒数十万次的读写操作（读的速度是 110000次/s，写的速度是 81000次/s）。单线程，事务驱动来处理并发请求。

特性：持久化（RDB，AOF）；分布式特性（主从复制，哨兵模式，集群模式）；支持发布订阅（pub/sub）——可作为消息队列：通知——分布式缓存更新，敏感操作审计；key过期——实时系统；支持lua脚本实现高级功能

应用场景：缓存（内存数据库，高性能读写）；消息队列（支持pub/sub）；会话管理（保存用户会话信息）；分布式锁（原子性）

2. 基本操作

2.1 登录

2.1.1 创建redis容器

# 使用默认配置启动
docker run -d --name redis0 -p 6379:6379 redis:latest

# 挂载配置文件启动：redis-server /usr/local/etc/redis/redis.conf  表示在容器内使用配置文件启动redis服务端
docker run -d --name redis -p 6379:6379 -v /path/to/redis.conf:/usr/local/etc/redis/redis.conf redis:latest redis-server /usr/local/etc/redis/redis.conf

2.1.2 redis-cli登录

连接

# 直接连接
docker exec -it redis0 redis-cli  

# 先进入容器，再连接redis服务端
docker exec -it redis0 /bin/bash
redis-cli -h host -p port

检测服务是否运行

ping 		 # 返回PONG 响应证明redis-server正常
ping "hello" # 带参数的ping命令，返回"hello"。快速检测连接状态、服务器可用性，测量网络延迟以及验证协议兼容性

身份验证/ACL

redis 6开始引入ACL作为身份验证方式。每个用户有自己的用户名和密码，每个用户被分配了一定的权限。default用户在被修改之前具备全部权限（相当于root用户），要确保default用户的安全性。也常专门创建一个admin用户以管理其他用户。

# 查看所有用户信息
ACL LIST  # default: 默认用户，on: 该用户处于启用状态，nopass: 无需密码就能登录，~*: 可以访问所有键，+@all: 拥有所有命令的执行权限
"user default on nopass sanitize-payload ~* &* +@all"

# 查看指定用户信息
ACL GETUSER default

# 创建新用户
ACL SETUSER newuser on >password ~* +get +set

# 删除新用户
ACL DELUSER newuser

# 以特定用户身份登录redis
redis-cli -u redis://username:password@127.0.0.1:6379

传统密码验证模式：没有用户名，客户端执行auth成功后就可执行redis指令。

# redis.conf中通过配置项requirepass来设置密码
requirepass yourpassword

# 连接后验证
auth password

2.2 配置

配置文件：redis官方镜像中没有默认的redis.conf，如果需要挂载自定义的配置文件，注意要挂在到容器中的指定位置：/usr/local/etc/redis/redis.conf
redis.conf模板文件：https://redis.io/docs/latest/operate/oss_and_stack/management/config/
配置参数参考：https://www.runoob.com/redis/redis-conf.html

# 获取所有配置项
CONFIG GET *

# 获取配置项loglevel
CONFIG GET loglevel

# 设置配置项
CONFIG SET loglevel "notice"

2.3 Redis服务端管理

服务端统计信息含义参考：https://redis.io/docs/latest/commands/info/

# 查看服务端统计信息：Server，Clients，Memory，Persistence，Stats，Replication，CPU，Keyspace
INFO

2.4 补充

2.4.1 迭代查询key

用于迭代数据库中所有的key，一次迭代返回下次迭代起始游标值n1和本次迭代的所有key。


# 格式
SCAN cursor [MATCH pattern] [COUNT count] [TYPE type]

# 用法
scan 0   # 第一次迭代，返回游标值，n1
scan n1  # 第二次迭代，返回游标值，n2
scan n2  # 第三次迭代

# 指定期望返回n个扫描结果，实际返回结果数量可能不等于n
scan <cursor> n

# 用于批量删除
scan <cursor> match '<match_pattern>'

2.4.2 批量删除

redis-cli -a "passwd" --scan --pattern '<pattern>' | xargs redis-cli -a "passwd" del

2.4.3 其他常用命令

# 查看帮助
help cmd

# Returns all key names that match a pattern.
KEYS pattern

# Deletes one or more keys
DEL key [key ...]

# Determines whether one or more keys exist
EXISTS key [key ...]

# Sets the expiration time of a key in seconds
EXPIRE key seconds [NX|XX|GT|LT]

# Returns the expiration time in seconds of a key.
TTL key

3. 基本数据类型

多元素类型支持的最大元素个数可以查redis官方文档ai助手：https://redis.io/chat?q=max+elements+of+zset&page=1。提示词：The maximum number of elements in a sorted set/set/list/hash

3.1 String

二进制安全：Redis 在处理字符串时，能够准确无误地存储和读取任何二进制数据，而不会对数据进行任何修改或截断。这使得string 可以包含任何数据（文本、图像、音频、视频）。

maxsize：512MB

SET key val
GET key

MSET k1 v1 k2 v2
MGET k1 k2

# Increments the integer value of a key by one. Uses 0 as initial value if the key doesn't exist
incr key

# Increments the integer value of a key by a number. Uses 0 as initial value if the key doesn't exist
INCRBY key increment

# Increment the floating point value of a key by a number. Uses 0 as initial value if the key doesn't exist
INCRBYFLOAT key increment

# Sets the string value and expiration time of a key. Creates the key if it doesn't exist
SETEX key seconds value

# Set the string value of a key only when the key doesn't exist
SETNX key value

3.2 hash

hash表：kv集合，值类型必须是string类型，而不能是hash表类型。可以使用多级哈希表模拟嵌套结构，第一层hash表重

基本用法

HSET key field value [field value ...]
HGET key field

HMSET key field value [field value ...]
HMGET key field [field ...]

HGETALL key

# return all fields of the key
HKEYS key
# return all values in a hash
HVALS key

# Increments the integer value of a field in a hash by a number. Uses 0 as initial value if the field doesn't exist
HINCRBY key field increment

# Sets the value of a field in a hash only when the field doesn't exist
HSETNX key field value

模拟嵌套hash表

# 创建外层哈希表
HSET outer_hash nested_key nested_hash_key

# 创建内层哈希表
HSET nested_hash_key subfield1 subvalue1
HSET nested_hash_key subfield2 subvalue2

# 从外层到内层访问
HGET outer_hash nested_key  	# 访问外层hash表，得到nested_hash_key
HGET nested_hash_key subfield1  # 访问内层hash表

3.3 List

string列表，头部/左边插入或者尾部/右边插入

LPUSHLPUSH key element [element ...]
RPUSHLPUSH key element [element ...]

# Returns the first elements in a list after removing it. Deletes the list if the last element was popped. count decide how many elements will be popped from the head of the list
LPOP key [count]
RPOP key [count]

LRANGE key start stop

# Removes and returns the first element in a list. Blocks until an element is available otherwise. Deletes the list if the last element was popped.
BLPOP key [key ...] timeout

3.4 Set

无序集合，基于哈希表实现的，插入，删除，查询O(1)

# Adds one or more members to a set. Creates the key if it doesn't exist.
SADD key member [member ...]

# Removes one or more members from a set. Deletes the set if the last member was removed.
SREM key member [member ...]

# Returns the number of members in a set.
SCARD key

# Determines whether a member belongs to a set.
SISMEMBER key member

# Returns all members of a set.
SMEMBERS key

3.5 Sorted Set

string集合，不允许重复值，每个元素配一个score，score可以重复，通过scoore来确定元素偏序。

# Adds one or more members to a sorted set, or updates their scores. Creates the key if it doesn't exist.
ZADD key [NX|XX] [GT|LT] [CH] [INCR] score member [score member ...]

# Removes one or more members from a sorted set. Deletes the sorted set if all members were removed.
ZREM key member [member ...]

# Returns the score of a member in a sorted set.
ZSCORE key member

# Increments the score of a member in a sorted set.
ZINCRBY key increment member

# Returns the number of members in a sorted set.
ZCARD key

# Returns the index of a member in a sorted set ordered by ascending scores.
ZRANK key member [WITHSCORE]

# Returns the index of a member in a sorted set ordered by descending scores.
ZREVRANK key member [WITHSCORE]

# Returns the count of members in a sorted set that have scores within a range.
ZCOUNT key min max

# Returns members in a sorted set within a range of indexes.
ZRANGE key start stop [BYSCORE|BYLEX] [REV] [LIMIT offset count] [WITHSCORES]

# Returns members in a sorted set within a range of indexes in reverse order.
ZREVRANGE key start stop [WITHSCORES]

# Returns members in a sorted set within a range of scores.
ZRANGEBYSCORE key min max [WITHSCORES] [LIMIT offset count]

# Returns the difference between multiple sorted sets.
ZDIFF numkeys key [key ...] [WITHSCORES]

# Returns the intersect of multiple sorted sets.
ZINTER numkeys key [key ...] [WEIGHTS weight [weight ...]] [AGGREGATE SUM|MIN|MAX] [WITHSCORES]

# Returns the union of multiple sorted sets.
ZUNION numkeys key [key ...] [WEIGHTS weight [weight ...]] [AGGREGATE SUM|MIN|MAX] [WITHSCORES]