Redis的String类型

Redis的基本使用

# 默认连接 6379端口 exit退出
redis-cli 
# 指定6380端口连接 默认进入0号库
redis-cli -p 6380
[root@redis-01 /proc/21622/fd]# redis-cli -p 6380
127.0.0.1:6380> set k380:1 hello  # 设置key与value
OK
127.0.0.1:6380> get k380:1        # 通过key查询value
"hello"
127.0.0.1:6380> select 8          # 选择8号库
OK
127.0.0.1:6380[8]> get k380:1     # 查询不到数据
(nil)
# 看帮助文档
redis-cli -h
redis-cli -h 选择主机名
redis-cli -n 选择数据库
# redis默认是有16个库 从0~15号库
redis-cli --raw # 格式化

Redis的string类型详解

redis-cli
[root@redis-01 /proc/21622/fd]# redis-cli
127.0.0.1:6379> help
redis-cli 5.0.5
To get help about Redis commands type:
      "help @<group>" to get a list of commands in <group>  # 查看该组下的帮助文档
      "help <command>" for help on <command>                # 查看该命令的帮助文档
      "help <tab>" to get a list of possible help topics    # help 后按tab键挨个提示命令
      "quit" to exit

To set redis-cli preferences:
      ":set hints" enable online hints
      ":set nohints" disable online hints
Set your preferences in ~/.redisclirc
127.0.0.1:6379> help @generic                 # 查看通用组的命令

  DEL key [key ...]     # 删除key
  summary: Delete a key
  # 
  since: 1.0.0

  DUMP key
  summary: Return a serialized version of the value stored at the specified key.
  # 
  since: 2.6.0

  EXISTS key [key ...]  # 判断key是否存在
  summary: Determine if a key exists
  # 
  since: 1.0.0

  EXPIRE key seconds    # key的存活时间
  summary: Set a key's time to live in seconds
  # 
  since: 1.0.0

  EXPIREAT key timestamp
  summary: Set the expiration for a key as a UNIX timestamp
  # 
  since: 1.2.0

  KEYS pattern         # keys 接个通配符 查询key
  summary: Find all keys matching the given pattern
  # 
  since: 1.0.0

  MIGRATE host port key| destination-db timeout [COPY] [REPLACE] [KEYS key]
  summary: Atomically transfer a key from a Redis instance to another one.
  # 
  since: 2.6.0

  MOVE key db         # 移动key到某个数据库
  summary: Move a key to another database
  # 
  since: 1.0.0

  OBJECT subcommand [arguments [arguments ...]]  # 查询key自身的Object定义
  #127.0.0.1:6379> OBJECT encoding k2 # 检查k2对应的value为什么编码格式
  #"embstr"
  #127.0.0.1:6379> OBJECT encoding k1 # 当编码格式为int时那么就可以使用面向数值的指令了
  #"int"
  summary: Inspect the internals of Redis objects # 检查Redis对象的内部
  # 
  since: 2.2.3

  PERSIST key
  summary: Remove the expiration from a key
  # 
  since: 2.2.0

  PEXPIRE key milliseconds
  summary: Set a key's time to live in milliseconds
  # 
  since: 2.6.0

  PEXPIREAT key milliseconds-timestamp
  summary: Set the expiration for a key as a UNIX timestamp specified in milliseconds
  # 
  since: 2.6.0

  PTTL key
  summary: Get the time to live for a key in milliseconds
  # 
  since: 2.6.0

  RANDOMKEY -
  summary: Return a random key from the keyspace
  # 
  since: 1.0.0

  RENAME key newkey
  summary: Rename a key
  # 
  since: 1.0.0

  RENAMENX key newkey
  summary: Rename a key, only if the new key does not exist
  # 
  since: 1.0.0

  RESTORE key ttl serialized-value [REPLACE]
  summary: Create a key using the provided serialized value, previously obtained using DUMP.
  # 
  since: 2.6.0

  SCAN cursor [MATCH pattern] [COUNT count]
  summary: Incrementally iterate the keys space
  # 
  since: 2.8.0

  SORT key [BY pattern] [LIMIT offset count] [GET pattern [GET pattern ...]] [ASC|DESC] [ALPHA] [STORE destination]
  summary: Sort the elements in a list, set or sorted set
  # 
  since: 1.0.0

  TOUCH key [key ...]
  summary: Alters the last access time of a key(s). Returns the number of existing keys specified.
  # 
  since: 3.2.1

  TTL key
  summary: Get the time to live for a key
  # 
  since: 1.0.0

  TYPE key        # 查看key对应的value的类型
  summary: Determine the type stored at key
  # 
  since: 1.0.0

  UNLINK key [key ...]
  summary: Delete a key asynchronously in another thread. Otherwise it is just as DEL, but non blocking.
  # 
  since: 4.0.0

  WAIT numreplicas timeout
  summary: Wait for the synchronous replication of all the write commands sent in the context of the current connection
  # 
  since: 3.0.0

  HOST: ...options...
  summary: Help not available
  # 
  since: not known

  PFDEBUG arg arg ...options...
  summary: Help not available
  # 
  since: not known

  PFSELFTEST 
  summary: Help not available
  # 
  since: not known

  LATENCY arg ...options...
  summary: Help not available
  # 
  since: not known

  PSYNC arg arg 
  summary: Help not available
  # 
  since: not known

  SUBSTR key arg arg 
  summary: Help not available
  # 
  since: not known

  RESTORE-ASKING key arg arg ...options...
  summary: Help not available
  # 
  since: not known

  XSETID key arg 
  summary: Help not available
  # 
  since: not known

  GEORADIUS_RO key arg arg arg arg ...options...
  summary: Help not available
  # 
  since: not known

  POST ...options...
  summary: Help not available
  # 
  since: not known

  MODULE arg ...options...
  summary: Help not available
  # 
  since: not known

  REPLCONF ...options...
  summary: Help not available
  # 
  since: not known

  GEORADIUSBYMEMBER_RO key arg arg arg ...options...
  summary: Help not available
  # 
  since: not known

  LOLWUT ...options...
  summary: Help not available
  # 
  since: not known

  ASKING 
  summary: Help not available
  # 
  since: not known
  #127.0.0.1:6379> keys *    # 查询所有的keys
  #1) "k1"
  #2) "a"
  #3) "k11"
  #127.0.0.1:6379> FLUSHALL # 清库操作 生产中不要使用这个 一般运维会改名
  #OK
  #127.0.0.1:6379> FLUSHDB  # 清库操作 生产中不要使用这个 一般运维会改名
  #OK
  #127.0.0.1:6379> keys *
  #(empty list or set)
  # Redis中key是string，Redis中的value有五种基本类型 string、list、set、sorted_set、hash
  # key中有指针指向value
  # pubsub 消息队列
  # transactions 事务
127.0.0.1:6379> help @string
# 1、字符串
    
  SET key value [expiration EX seconds|PX milliseconds] [NX|XX]  
  # 设置
  # NX -> set k1 aaa nx  当k1不存在时才设置值(只能新建，拿到锁) -> 适用场景为分布式锁
  # XX -> set k2 hello xx 当k2存在时才设置值(只能更新)  
  summary: Set the string value of a key
  # 设置一个key的value值
  since: 1.0.0
  
  GET key     # 取出
  summary: Get the value of a key
  # 返回key的value
  since: 1.0.0
  
  
  MGET key [key ...] # 多个取出
  summary: Get the values of all the given keys
  # 获得所有key的值
  since: 1.0.0

  MSET key value [key value ...] # 多个设置 
  summary: Set multiple keys to multiple values
  # 设置多个key value
  since: 1.0.1
  #127.0.0.1:6379> mset k3 a k4 b
  #OK
  #127.0.0.1:6379> mget k3 k4
  #1) "a"
  #2) "b"

  APPEND key value # 往后追加字符串
  # APPEND k1 " world"
  # get k1 -> hello world
  summary: Append a value to a key
  # 追加一个值到key上
  since: 2.0.0
  
  SETRANGE key offset value  # 从value中的偏移量中更改值
  # k4 -> hello world
  #127.0.0.1:6379> SETRANGE k4 6 yangyanchao
  #(integer) 17
  #127.0.0.1:6379> get k4
  #"hello yangyanchao"
  summary: Overwrite part of a string at key starting at the specified offset
  # 从value中的偏移量中更改值
  since: 2.2.0
  
  GETRANGE key start end # 得到部分字符串
  #127.0.0.1:6379> GETRANGE k4 6 10   # 正向索引 从0开始
  #"world"
  #127.0.0.1:6379> GETRANGE k4 6 -1   # 反向索引 倒数从-1开始
  #"world"
  summary: Get a substring of the string stored at a key
  # 获取存储在key上的值的一个子字符串
  since: 2.4.0
  
  GETSET key value # 设置新的值但是返回老的值     减少一次IO通讯
  summary: Set the string value of a key and return its old value
  # 设置一个key的value，并获取设置前的值
  since: 1.0.0

  STRLEN key     # 获取字节数
  #127.0.0.1:6379> STRLEN k4
  #(integer) 17
  #127.0.0.1:6379> get k4
  #"hello yangyanchao"
  summary: Get the length of the value stored in a key
  # 获取指定key值的长度
  since: 2.2.0
  
  MSETNX key value [key value ...] # 多个赋值不存在的key 若有一个key存在则操作不执行 原子性操作
  summary: Set multiple keys to multiple values, only if none of the keys exist
  # 设置多个key value,仅当key存在时
  since: 1.0.1
  #127.0.0.1:6379> MSETNX k1 a k2 b
  #(integer) 1
  #127.0.0.1:6379> MGET k1 k2
  #1) "a"
  #2) "b"
  #127.0.0.1:6379> MSETNX k2 c k3 d # k2存在 失败了 导致 k2、k3整个赋不了值
  #(integer) 0
  #127.0.0.1:6379> mget k1 k2 k3
  #1) "a"
  #2) "b"
  #3) (nil)

  PSETEX key milliseconds value    # 设置键的值和过期时间（以毫秒为单位）
  summary: Set the value and expiration in milliseconds of a key
  # 设置key-value并过期时间（以毫秒为单位）
  since: 2.6.0
  
  SETEX key seconds value         # 设置键的值和过期时间
  summary: Set the value and expiration of a key
  # 设置key-value并设置过期时间（单位：秒）
  since: 2.0.0

  SETNX key value       # 仅当键不存在时，才设置键的值 -> 适用场景为分布式锁
  summary: Set the value of a key, only if the key does not exist
  # 设置键，只有当该键不存在
  since: 1.0.0
  
# 2、数值
# 抢购，秒杀，详情页，点赞，评论
# 规避并发下，对数据库的事务操作 如果数值的变化落到关系型数据库必须要触发事务操作 影响性能
# 完全由redis内存操作代替 若是Redis中数值的变化落到内存处理 规避数据库事务 提升性能
  DECR key             # key中value-1 自减1
  summary: Decrement the integer value of a key by one
  # 整数原子减1
  since: 1.0.0

  DECRBY key decrement   # key中value-decrement 自减decrement
  summary: Decrement the integer value of a key by the given number
  # 原子减指定的整数
  since: 1.0.0
  
  INCR key                # key中value+1 自增1
  summary: Increment the integer value of a key by one
  # 执行原子加1操作
  since: 1.0.0

  INCRBY key increment   # key中value+increment 自增increment
  summary: Increment the integer value of a key by the given amount
  # 执行原子增加一个整数
  since: 1.0.0

  INCRBYFLOAT key increment # key中value+increment 自增increment 浮点数
  summary: Increment the float value of a key by the given amount
  # 执行原子增加一个浮点数
  since: 2.6.0
  # 演示数值
  #127.0.0.1:6379> INCR k1
  #(integer) 100
  #127.0.0.1:6379> get k1
  #"100"
  #127.0.0.1:6379> INCRBY k1 23
  #(integer) 123
  #127.0.0.1:6379> get k1
  #"123"
  #127.0.0.1:6379> DECR k1
  #(integer) 122
  #127.0.0.1:6379> DECR k1 22
  #(error) ERR wrong number of arguments for 'decr' command
  #127.0.0.1:6379> DECRBY k1 22
  #(integer) 100
  #127.0.0.1:6379> get k1
  #"100"
  #127.0.0.1:6379> INCRBYFLOAT k1 0.5
  #"100.5"
  #127.0.0.1:6379> get k1
  #"100.5"
  # 演示长度变化及一些指令能够修改编码格式
  #127.0.0.1:6379> set k1 hello
  #OK
  #127.0.0.1:6379> STRLEN k1
  #(integer) 5
  #127.0.0.1:6379> set k2 9
  #OK
  #127.0.0.1:6379> OBJECT encoding k2
  #"int"
  #127.0.0.1:6379> STRLEN k2
  #(integer) 1
  #127.0.0.1:6379> append k2 99
  #(integer) 3
  #127.0.0.1:6379> append k2 9   # append能将编码改为raw
  #(integer) 4
  #127.0.0.1:6379> object encoding k2
  #"raw"
  #127.0.0.1:6379> INCR k2      # INCR能将编码改为int
  #(integer) 10000
  #127.0.0.1:6379> object encoding k2
  #"int"
  #127.0.0.1:6379> STRLEN k2
  #(integer) 5
  #127.0.0.1:6379> set k3 a
  #OK
  #127.0.0.1:6379> get k3
  #"a"
  #127.0.0.1:6379> STRLEN k3
  #(integer) 1
  #127.0.0.1:6379> APPEND k3 中
  #(integer) 4
  #127.0.0.1:6379> STRLEN k3         # 为什么会是4？ 这里涉及到Redis的二进制安全
  #(integer) 4
  #127.0.0.1:6379> get k3
  #"a\xe4\xb8\xad"
  # 二进制安全 -> Redis中从socket中只拿到了字节流并没有拿字符流 为了适应各种语言
  # Redis的编码并不影响数据存储
  #127.0.0.1:6379> set k2 中
  #OK
  #127.0.0.1:6379> STRLEN k2
  #(integer) 3
  #127.0.0.1:6379> get k2
  #"\xe4\xb8\xad"
  
  # 上面一个"中" 为什么是3个字节，是由客户端程序编码决定的 
  # 例如xshell软件(属性-终端-编码)与Redis通讯是UTF-8 切换为GBK
  #127.0.0.1:6379> set k3 中
  #OK
  #127.0.0.1:6379> STRLEN k3
  #(integer) 2
  #127.0.0.1:6379> get k3
  #"\xd6\xd0"
  # 因为"中"在UTF-8编码中占用3字节，而在GBK中占用2字节
  # 退出Redis-cli
  #exit
  #redis-cli --raw   # 按照客户端软件(xshell)编码级的格式化 不加raw默认是ACSII码
  #127.0.0.1:6379> get k2
  #涓
  #127.0.0.1:6379> get k3
  #中

# 3、bitmap

  BITCOUNT key [start end]    # start与end是字节索引不是位索引
  summary: Count set bits in a string # 返回二进制1的个数 在start~end范围上
  # 统计字符串指定起始位置的字节数
  since: 2.6.0
  #127.0.0.1:6379> BITCOUNT k1 0 1
  #(integer) 3
  #127.0.0.1:6379> BITCOUNT k1 0 0
  #(integer) 2
  #127.0.0.1:6379> BITCOUNT k1 1 1
  #(integer) 1
  #01000001 01000000 -> "A@"
  #01234567 89ABCDEF -> 二进制位索引位置(偏移量)
  # 0        1       -> 字节索引位置
  # 2        1       -> 每字节的二进制1的个数

  BITFIELD key [GET type offset] [SET type offset value] [INCRBY type offset increment] [OVERFLOW WRAP|SAT|FAIL]
  summary: Perform arbitrary bitfield integer operations on strings
  # 
  since: 3.2.0

  BITOP operation destkey key [key ...] # 二进制操作 destkey目标key key [key ...] 很多key 
  summary: Perform bitwise operations between strings 
  # 
  # 操作 将key [key ...]按位与、按位或、按位非、按位异或 结果存入destkey
  since: 2.6.0
  #127.0.0.1:6379> setbit k1 1 1
  #(integer) 0
  #127.0.0.1:6379> setbit k1 7 1
  #(integer) 0
  #127.0.0.1:6379> get k1
  #"A"
  #01000001 -> "A"
  #127.0.0.1:6379> setbit k2 1 1
  #(integer) 0
  #127.0.0.1:6379> setbit k2 6 1
  #(integer) 0
  #127.0.0.1:6379> get k2
  #"B"
  #01000010 -> "B"
  #127.0.0.1:6379> bitop and andkey k1 k2  按位与&
  #(integer) 1
  #01000001 -> "A"
  #01000010 -> "B"
  # 按位与&
  #01000000 -> "@"
  #127.0.0.1:6379> get andkey
  #"@"
  #127.0.0.1:6379> bitop or orkey k1 k2  按位或|
  #(integer) 1
  #01000001 -> "A"
  #01000010 -> "B"
  # 按位或|
  #01000011 -> "C"
  #127.0.0.1:6379> get orkey
  #"C"

  BITPOS key bit [start] [end] # start与end是字节索引不是位索引
  summary: Find first bit set or clear in a string # 返回首个二进制位bit的偏移量 在start~end范围上
  # 
  since: 2.8.7
  #127.0.0.1:6379> bitpos k1 1 0 0   # 在0字节索引位置上出现第一个bit是1的偏移量为1
  #(integer) 1
  #127.0.0.1:6379> bitpos k1 1 1 1   # 在1字节索引位置上出现第一个bit是1的偏移量为9
  #(integer) 9
  #01000001 01000000 -> "A@"
  #01234567 89ABCDEF -> 二进制位索引位置(偏移量)
  # 0        1       -> 字节索引位置
  
  GETBIT key offset
  summary: Returns the bit value at offset in the string value stored at key
  # 
  since: 2.2.0

  SETBIT key offset value # offset 是二进制位的偏移量
  #127.0.0.1:6379> setbit k1 1 1
  #00000000 -> 将索引位1上的二进制数改为1 -> 01000000 -> "@"
  #01234567 -> 索引位置
  #(integer) 0
  #127.0.0.1:6379> STRLEN k1
  #(integer) 1
  #127.0.0.1:6379> get k1
  #"@"
  #127.0.0.1:6379> setbit k1 7 1
  #01000000 -> 将索引位7上的二进制数改为1 -> 01000001 -> "A"
  #01234567 -> 索引位置
  #(integer) 0
  #127.0.0.1:6379> STRLEN k1
  #(integer) 1
  #127.0.0.1:6379> get k1
  #"A"
  #127.0.0.1:6379> setbit k1 9 1
  #01000001 00000000 -> 将索引位9上的二进制数改为1 -> 01000001 01000000 -> "A@"
  #01234567 89ABCDEF -> 索引位置
  #(integer) 0
  #127.0.0.1:6379> STRLEN k1
  #(integer) 2
  #127.0.0.1:6379> get k1
  #"A@"
  # 字符编码小插曲
  # 字符集  ascii其他一般叫做扩展字符集  扩展：其他字符集不再对ascii重编码0xxxxxxx
  # 你自己写一个程序，字节流读取，每字节判断
  summary: Sets or clears the bit at offset in the string value stored at key
  # 
  since: 2.2.0
# bitmap场景
#1,有用户系统，统计用户登录天数，且窗口随机
# 假如sean用户在去年的某一天(9月1日)的上一周与下一周(窗口随机)统计这个时间段的登录天数
# 设计思路： 一年中有365、366天 那么就假设每年是400天 每一天对应一个二进制位 400/8=50个Byte 
# 使用这个50Byte记录一个用户全年的登录状态  用户为key 天数为二进制位
#setbit sean 1 1      # sean用户 在第2天登录了
#setbit sean 7 1      # sean用户 在第8天登录了
#setbit sean 364 1    # sean用户 在第365天登录了
#STRLEN sean
#46                   # 占用46Byte
#BITCOUNT sean -2 -1  # sean用户 最后两周登录的天数
#2，京东618做活动：送礼物
#假设京东一共有2亿用户，618当天登录就送礼物，一个用户只能获得一个礼物，大库备货多少礼物？
#电商常识：用户分为僵尸用户、冷热用户/忠诚用户
#需要做的就是同比去年或者某个时间段 有多少活跃用户？如果获得了具体的活跃用户再涨个20%或者30%做个估算

#活跃用户统计！随机窗口
#比如说 1号~3号  连续登录要     去重 一个用户在这三天内连续登录要去重的
# 将不同的用户映射到不同的二进制位上 比如：二进制位1->yangyc 二进制位7 ->wumx
# 天数为key 用户id为二进制位
#setbit 20190101   1  1
#setbit 20190102   1  1
#setbit 20190102   7  1
#bitop  or   destkey 20190101  20190102  # 进行或运算去重操作
#BITCOUNT  destkey  0 -1 # 统计