一文了解：Redis基础类型

2019 年 10 月 3 日
笔记

一文了解：Redis基础类型

Redis特点

开源的，BSD许可高级的key-value存储系统
可以用来存储字符串，哈希结构，链表，集合

安装

windows：https://github.com/microsoftarchive/redis/releases

maclinux：http://www.redis.cn/

Redis 数据类型

Redis支持五种数据类型：string（字符串），hash（哈希），list（列表），set（集合）及zset（有序集合）。

string（字符串）

字符串类型是Redis的最基本数据结构。
字符串类型的值实际可以为字符串，数字，二进制，但是值最大不能超过512M。

key	value
hello	world
counter	1
bits	10000100
json	{"id":1,"name":"xiaocai","age":18}

string命令

设置

set key value [EX seconds] [PX milliseconds] [NX|XX]

get key

> set name xiaocai  OK  > get name  "xiaocai"

过期

setex key seconds value

> set name1 redis1 ex 10 #10秒后过期  OK  > get name1  (nil)    > setex name2 10 redis2 #10秒后过期  OK  > get name2  "redis2"  > get name2  (nil)    > set name3 redis3 px 10 #10豪秒后过期  OK  > get name3  (nil)

不存在才能设置成功或者必须存在才能设置成功

> set hello world nx #不存在才能设置成功  OK  > set hello w nx #存在就设置失败  (nil)  > get hello  "world"    >set hello w xx  #存在才能设置成功  OK  > set world hello xx #不存在就设置失败  (nil)  > get hello  "w"  > get world  (nil)

批量设置

mset key value [key value ...]  mget key [key ...]      > mset name1 redis1 name2 redis2  OK    > mget name1 name2  1) "redis1"  2) "redis2"    > mget name1 name2 name3  1) "redis1"  2) "redis2"  3) (nil)

计数

incr key

incrby key increment

> set age 18  #value只能为整数  OK  > incr age  (integer) 19  > incrby age -5  (integer) 14  > incrby age 10  (integer) 24

删除

del key [key …]

> del age  (integer) 1  > get age  (nil)

内部编码

int 8个字节的长整型
embstr 小于等于39个字节的字符串
raw 大于39个字节的字符串

> set port 6379  OK  > object encoding port  "int"    > set hello world  OK  > object encoding hello  "embstr"    > set longString abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz  OK  > object encoding hello  "raw"  > strlen longString  (integer) 52

list（列表）

list类型是用来存储多个有序的字符串。每列字符串称之为元素。一个list的最大存储为2^32-1个元素。可以对列表进行双端插入和弹出，也可以指定索引下标获取元素。

list命令

头部和尾部添加元素

lpush key value [value …]

rpush key value [value …]

lrange key start stop

> lpush letter "a"  (integer) 1  > lpush letter "b"  (integer) 2  > lpush letter "c"  (integer) 3  > lrange letter 0 -1  1) "c"  2) "b"  3) "a"    > rpush letter "a"  (integer) 4  > rpush letter "b"  (integer) 5  > rpush letter "c"  > lrange letter 0 -1  1) "c"  2) "b"  3) "a"  4) "a"  5) "b"  6) "c"

头部和尾部弹出元素

lpop key

rpop key

> lpop letter  "c"  > lpop letter  "b"  > lrange letter 0 -1  1) "a"  2) "a"  3) "b"  4) "c"    > rpop letter  "c"  > rpop letter  "b"  > lrange letter 0 -1  1) "a"  2) "a"

索引操作
索引需要对全部list进行遍历，性能会随着元素个数的增大而变差

lrange key start stop

lindex key index

ltrim key start stop

len key

> rpush letter b c  (integer) 4  > lrange letter 0 -1  1) "a"  2) "a"  3) "b"  4) "c"  > lindex letter 2  "b"  > ltrim letter 0 -2  OK  > lrange letter 0 -1  1) "a"  2) "a"  3) "b"  > llen letter  (integer) 3

插入

insert key BEFORE|AFTER pivot value

> linsert letter before b c  (integer) 4  > linsert letter after a d  (integer) 5  > lrange letter 0 -1  1) "a"  2) "d"  3) "a"  4) "c"  5) "b"

修改

set key index value

> lset letter 2 B  OK  > lrange letter 0 -1  1) "a"  2) "d"  3) "B"  4) "c"  5) "b"

内部编码

ziplist（压缩列表）：小于3.2版本，当元素个数小于list-max-ziplist-entries配置（默认512个），同时每个元素的值长度都小于list-max-ziplist-value配置（默认64字节）
linkedlist（链表）：小于3.2版本，不满足ziplist的条件
quicklist：Redis 3.2版本，以一个ziplist为节点的linkedlist

> object encoding letter  "quicklist"

hash (哈希)

hash是一个string类型的field和value的映射表。它适合用于存储对象，它是无序的，不能使用索引操作。

hash命令

设置

hset key field value

> hset user:1 name zhangSan  (integer) 1  > hset user:1 age 18  (integer) 1

获取和获取所有的field-value

hget key field

hgetall key

> hget user:1 name  "zhangSan"  > hgetall user:1  1) "name"  2) "zhangSan"  3) "age"  4) "18"

删除

hdel key field [field …]

> hdel user:1 age  (integer) 1  > hdel user:2 age  (integer) 0

长度

hlen key

> hlen user:1  (integer) 1

批量设置

hmset key field value [field value …]

> hmset user:2 name liSi age 23  OK  > hmget user:2 name age  1) "liSi"  2) "23"  > hlen user:1  (integer) 1  > hlen user:2  (integer) 2

是否存在

hexists key field

> hexists user:2 name  (integer) 1  > hexists user:2 city  (integer) 0

所有的field和所有的value

hkeys key

hvals key

> hkeys user:1  1) "name"  > hkeys user:2  1) "name"  2) "age"  > hvals user:1  1) "zhangSan"  > hvals user:2  1) "liSi"

内部编码

ziplist（压缩列表）：当元素个数小于hash-max-ziplist-entries配置（默认512个）和每个元素大小小于hash-max-ziplist-value配置（默认64字节）时
hashtable（哈希表）：不满足ziplist条件时

> object encoding user:1  "ziplist"

修改配置文件hash-max-ziplist-entries为5

> hmset test t1 v1 t2 v2 t3 v3 t4 v4 t5 v5 t6 v6  OK  > object encoding test  "hashtable"

set（集合）

用来保存多个字符串元素，无序的，不能有重复元素，不能使用索引下标获取元素。一个集合可以存储2^32-1个元素。

set命令

增加

add key member [member …]

> sadd user:1:tag it music news  (integer) 3  > sadd user:1:tag bike news  (integer) 1

删除

srem key member [member …]

> srem user:1:tag bike  (integer) 1

个数

scard key

> scard user:1:tag  (integer) 3

是否存在

sismember key member

> sismember user:1:tag bike  (integer) 0  > sismember user:1:tag it  (integer) 1

随机返回指定个数

srandmember key [count]

> srandmember user:1:tag  "news"  > srandmember user:1:tag 3  1) "news"  2) "music"  3) "it"

随机弹出

spop key [count]

> spop user:1:tag  "news"  > srandmember user:1:tag 3  1) "music"  2) "it"

所有个数

smembers key

> smembers user:1:tag  1) "music"  2) "it"

交集

sinter key [key …]

> sinter user:1:tag user:2:tag  1) "music"  2) "it"

并集

sunion key [key …]

> sunion user:1:tag user:2:tag  1) "music"  2) "java"  3) "run"  4) "it"

差集

sdiff key [key …]

> sdiff user:1:tag user:2:tag  (empty list or set)  > sadd user:1:tag sleep  (integer) 1  > sdiff user:1:tag user:2:tag  1) "sleep"  > sdiff user:2:tag user:1:tag  1) "java"  2) "run"

内部编码

intset（整数集合）：元素都是整数和元素个数小于set-max-intset-entries配置（默认512个）时
hashtable（哈希表）：不满足intset时

> object encoding user:1:tag  "hashtable"    > sadd numbers 1 2 3 4 5  (integer) 5  > object encoding numbers  "intset"

zset（有序集合）

zset保证了元素不能重复，每个元素都有一个分数（score）作为排序的依据。

zset命令

添加

zadd key [NX|XX] [CH] [INCR] score member [score member …]

> zadd books 8.2 "Redis in Action"  (integer) 1  > zadd books 9.3 "Effective Java: Second Edition : Java"  (integer) 1  > zadd books 9.1 "Think in Java"  (integer) 1  > zadd books 9.3 "Python Cookbook" 9.0 "Effective Python"  (integer) 2

个数

zcard key

> zcard books  (integer) 5

升序返回范围的成员

zrange key start stop [WITHSCORES]

> zrange books 0 -1  1) "Redis in Action"  2) "Effective Python"  3) "Think in Java"  4) "Effective Java: Second Edition : Java"  5) "Python Cookbook"    > zrange books 2 5  1) "Think in Java"  2) "Effective Java: Second Edition : Java"  3) "Python Cookbook"

升序返回成员时带上分数

> zrange books 0 -1 withscores   1) "Redis in Action"   2) "8.1999999999999993"   3) "Effective Python"   4) "9"   5) "Think in Java"   6) "9.0999999999999996"   7) "Effective Java: Second Edition : Java"   8) "9.3000000000000007"   9) "Python Cookbook"  10) "9.3000000000000007"    > zrange books 2 5 withscores  1) "Think in Java"  2) "9.0999999999999996"  3) "Effective Java: Second Edition : Java"  4) "9.3000000000000007"  5) "Python Cookbook"  6) "9.3000000000000007"

精度问题：内部 score 使用 double 类型进行存储，所以存在小数点精度问题
withscores:带上分数

降序

zrevrange key start stop [WITHSCORES]

> zrevrange books 0 -1 withscores   1) "Python Cookbook"   2) "9.3000000000000007"   3) "Effective Java: Second Edition : Java"   4) "9.3000000000000007"   5) "Think in Java"   6) "9.0999999999999996"   7) "Effective Python"   8) "9"   9) "Redis in Action"  10) "8.1999999999999993"

指定value的score

zscore key member

> zscore books "Think in Java"  "9.0999999999999996"

根据score的数值区间升序

zrangebyscore key min max [WITHSCORES] [LIMIT offset count]

> zrangebyscore books 0 9.1 withscores  1) "Redis in Action"  2) "8.1999999999999993"  3) "Effective Python"  4) "9"  5) "Think in Java"  6) "9.0999999999999996"

根据score的数值区间降序

zrevrangebyscore key max min [WITHSCORES] [LIMIT offset count]

> zrevrangebyscore books 9.1 0  withscores  1) "Think in Java"  2) "9.0999999999999996"  3) "Effective Python"  4) "9"  5) "Redis in Action"  6) "8.1999999999999993"

根据score的数值降序输出所有元素

> zrevrangebyscore books +inf -inf  withscores   1) "Python Cookbook"   2) "9.3000000000000007"   3) "Effective Java: Second Edition : Java"   4) "9.3000000000000007"   5) "Think in Java"   6) "9.0999999999999996"   7) "Effective Python"   8) "9"   9) "Redis in Action"  10) "8.1999999999999993"

+inf 正无穷
-inf 负无穷

删除

zrem key member [member …]

> zrem books "Effective Java: Second Edition : Java"  (integer) 1

增加分数

zincrby key increment member

> zincrby books 2  "Redis in Action"  "10.199999999999999"  > zincrby books -1  "Redis in Action"  "9.1999999999999993"

交集

zinterstore destination numkeys key [key …] [WEIGHTS weight] [AGGREGATE

> zadd textbooks 8 "chinese" 9 "english" 9.5 "mathematics"  (integer) 3  > zadd textbooks 9.2 "Think in Java"  (integer) 1    > zrange books 0 -1  1) "Redis in Action"  2) "Effective Python"  3) "Think in Java"  4) "Python Cookbook"  > zrange textbooks 0 -1  1) "chinese"  2) "english"  3) "Think in Java"  4) "mathematics"    > zinterstore newbooks 2 books textbooks  (integer) 1  > zrange newbooks 0 -1  1) "Think in Java"

并集

zunionstore destination numkeys key [key …] [WEIGHTS weight] [AGGREGATE

> zunionstore newUnionbooks 2 books textbooks  (integer) 7  > zrange newUnionbooks 0 -1  1) "chinese"  2) "Redis in Action"  3) "Effective Python"  4) "english"  5) "Python Cookbook"  6) "mathematics"  7) "Think in Java"

内部编码

ziplist（压缩列表）：元素个数小于zset-max-ziplist-entries配置（默认128个）和元素长度小于zset-max-ziplist-value配置（默认64B）时
skiplist（跳跃表）：不满足ziplist时

> object encoding books  "ziplist"

结语

本人深知水平有限，欢迎指正本文错误之处。

参考资料

《Redis 实战》

《Redis 开发与运维》

《Redis 深度历险：核心原理与应用实践》

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