1. Brief introduction

Learning reference

https://blog.csdn.net/liqingtx/article/details/60330555

https://www.runoob.com/redis/redis-keys.html

Redis is a key:value storage system written in C language, supporting network interaction, memory-based or persistent, and value supports five data types

Strings, lists of strings, sets, sorted sets, hashes

Two, key commonly used commands

command	description	usage	success	failure	Remarks
set	Create key	set key1 123	OK		Create an existing key, it will overwrite the former
setnx	When the key is created and the current keyname does not exist	setnx key1 123	1	0
setex	Create a key and set the expiration time (seconds)	setex key1 10 123	OK		Create an existing key, it will overwrite the former
psetex	Create a key and set the expiration time (milliseconds)	psetex key1 1000 123	OK
mset	Create multiple keys	mset key1 123 key2 456	OK
msetnx	When multiple keys are created and the current key does not exist	msetnx key1 123 key2 456	1	0
get	Return the value of the key	get key1	value	nil
mget	Return the value of multiple keys	mget key1 key2	Multiple value	nil
of	Delete key	of key1	1	0
exists	Check if the key exists	exists key1	1	0
keys	Find eligible keys	keys key1/keys key/keys	key name		Add * after the name, all names before * are searched
rename	Modify the key name	rename key1 key2	OK	no such key	Modifying an existing key will overwrite the existing key
renamenx	Modify the key name, only when the new key name does not exist	renamenx key1 key2	1	0
expire	Set key expiration time (seconds)	expire key1 10	1	0
expire	Set key expiration time (milliseconds)	perpire key1 1000	1	0
expireat	Set key expiration time (time stamp)	expireat key1 1293810000	1	0
persist	Remove key expiration time	persist key1	1	0
TTL	Return the remaining time of key expiration (seconds)	ttl key1	Seconds remaining	-1
PTTL	Return the remaining time of key expiration (milliseconds)	pttl key1	Ms remaining	-1
dump	Serialization key	dump key1	Serialized value	nil
scan	Iteration key	scan 0	Output keyname
move	Move the key to another database	move key1 1	1	0	Another inventory with the same key will fail, select 1, move to the corresponding library, 0 represents the original one

Three, strings (strings)

Maximum data storage
- 512MB
Numerical calculation maximum range (the maximum value of long in java)
- 9223372036854775807

command	description	example	success	failure	Remarks
getrange	String interception, starting with subscript 0	getrange key1 2 3	Returns the content of subscripts 2 to 3	Return empty string
setrange	Replace to the string, starting from a certain subscript	setrange key1 2 "xxx"	Returns the length of the string after replacement		Auto-fill spaces that exceed the length
append	Concatenate content after the original string	append key1 "xxx"	Returns the length of the splicing		If the key does not exist, the key-value will be created and set
strlen	Returns the length of the string	strlen key1	Return length	0
incr	+1 the stored number	incr key1	Return the added number		Non-number error, error with decimal point
incrby	Add the stored number according to the specified number	incrby key1 2	Return the added number		Non-number error, error with decimal point
incrbyfloat	Add the stored number according to the specified floating-point number	incrbyfloat key1 0.5	Return the added number		Integer error
decr	Number to be stored -1	decr key1	Return the subtracted number
decrby	Subtract the stored number according to the specified	decrby key1 2	Return the subtracted number

四、字符串列表（lists）

底层数据结构为双向链表，插入快，查询快，操作类似于栈

最大存储232个vlaue

命令	描述	例子	成功	失败	备注
Lpush	向左边头部添加一个或多个值	lpush ll 123 456	返回长度
Rpushx	向已存在的Key,左边头部添加一个或多个值	lpushx ll 123 456	返回长度	0
Rpush	向右边尾部添加一个或多个值	rpush ll 123 456	返回长度
Rpushx	向已存在的Key,右边尾部添加一个或多个值	rpushx ll 123 456	返回长度	0
lset	指定list索引修改	lset ll 0 123	OK
Lpop	移除掉左边第一个元素，并且返回	lpop ll	原list的第一个元素	nil
Rpop	移除掉右边尾部第一个元素，并且返回	rpop ll	原list的最后一个元素	nil
Blpop	设置时间(秒)，移除掉左边第一个元素，并且返回key和该元素	blpop ll 5	key和元素		设置5秒内没有结果，则返回 nil和时间
Lindex	通过索引查询元素	lindex ll 0	元素
llen	返回list长度	llen ll	返回长度
ltrim	指定区间保留元素，其它的移除	ltrim ll 0 1	OK

五、字符串集合（sets）

底层是一个无序的集合

命令	描述	例子	成功	失败	备注
sadd	添加一个或多个元素	sadd set 11 22	返回长度		相同的key会覆盖
smembers	返回全部的元素	smembers set	全部元素
sismember	判断元素存在	sismember set 11	1	0
scard	获取集合长度	scard set	返回长度
spop	随机移除一个元素	spop set	返回移除元素	nil
srem	移除一个或多个成员	srem set 11 22	返回移除数量
sscan	迭代元素	sscan set	返回全部元素

六、有序字符串集合（sorted sets）

有序集合，每个元素带有一个score进行定位

七、哈希（hashes）

一种键值对结构,相当于key-value 再套一层keyValue

hash 可以存储 232 - 1 个键值对

命令	描述	例子	成功	失败	备注
Hset	设置hset	hset hkey1 cc 123	1	0	设置已经存在的field，会覆盖前者
Hsetnx	设置hset，在当前fi字段不存在下	hsetnx hkey1 cc 123	1	0
Hmset	一次设置多个字段	Hmset hkey1 cc 123 bb 456	OK
Hget	获取hkey的字段的值	hget hkey1 cc	输出单个值	nil
Hgetall	获取hkey的所有字段和值	hgetall hkey1	输出全部字段和值
Hmget	获取多个字段值	hmget hkey1 cc bb	输出多个值	nil
Hkeys	获取hkey的字段	hkeys hkey1	输出全部的字段
Hvals	获取hkey的所有值	hvals hkey1	输出全部的值
Hscan	迭代hkey所有字段和值	hscan hkey1 0	输出全部字段和值
Hlen	获取hash字段数量	hlen hkey1	数量
Hincrby	对字段的进行相加，按指定的整数	hincrby hkey1 cc 2	返回相加后的
Hincrbyfloat	对字段的进行相加，按指定的小数	hincrbyfloat hkey1 cc 0.4	返回相加后的

redis (two) five data types