缓存数据库（nosql）-redis 1

ubuntu安装redis-server

sudo apt update

sudo apt install  redis-server

python：pip install redis

1、简介

　　redis是一个k-v存储系统，与memcached类似，但支持五种数据类型：String字符串、Hash哈希表、List列表、Set集合、SortedSet有序集合

五种数据类型均支持push/pop、add/remove，交集、并集、差集等操作，这些操作都是原子性操作。

　　redis、memcached将数据缓存到内存中。但是redis会周期性将数据写入硬盘或把修改操作写入追加的记录文件，并在此基础上实现了master-slave同步

　　redis有缓存功能，也能做消息队列

　　redis支持数据持久化，电脑关机数据还在

　　默认端口：6379，memcached自己指定

2、redis的优势？

　　a、因为数据存在内存，因此速度快，查找和操作时间复杂度是 O（1）

　　b、支持的数据类型多

　　c、支持事务

　　d、功能多：缓存，设置过期时间，消息队列

　　

　　e、memcached值是简单的字符串，redis支持的数据类型多

　　f、redis速度更快

　　g、redis可支持数据的持久化

3、使用

linux操作：

启动：redis-server

连接：redis-cli

String：help  set

SET key value [EX seconds] [PX milliseconds] [NX|XX]
  summary: Set the string value of a key
  since: 1.0.0
  group: string

127.0.0.1:6379> get name
"lyb"
127.0.0.1:6379> type name
string
127.0.0.1:6379> set nn 123
OK
127.0.0.1:6379> type nn
string
127.0.0.1:6379> keys *
1) "name"
2) "nn"

127.0.0.1:6379> ttl nn　　#查看过期时间，-1未设置过期时间
(integer) -1

127.0.0.1:6379> set qq www px 123123123
OK
127.0.0.1:6379> ttl qq　　　　#秒
(integer) 123119
127.0.0.1:6379> pttl qq　　#毫秒
(integer) 123113045

127.0.0.1:6379> set qq 123　　#key不存在设置，存在就覆盖
OK
127.0.0.1:6379> get qq
"123"
127.0.0.1:6379> set qq 456 nx　　#nx表示key存在就不设置，不存在就设置
(nil)
127.0.0.1:6379> get qq
"123"
127.0.0.1:6379> set qq 456 xx　　#xx表示key存在设置，不存在不设置
OK
127.0.0.1:6379> get qq
"456"

mset 批量设置

MSET key value [key value ...]
  summary: Set multiple keys to multiple values
  since: 1.0.1
  group: string

127.0.0.1:6379> mset q1 qq q2 qw
OK

setex 设置过期时间

SETEX key seconds value
  summary: Set the value and expiration of a key
  since: 2.0.0
  group: string

setnx

SETNX key value
  summary: Set the value of a key, only if the key does not exist
  since: 1.0.0
  group: string

mget 批量获取

MGET key [key ...]
  summary: Get the values of all the given keys
  since: 1.0.0
  group: string

127.0.0.1:6379> mget q1 name ddd
1) "qq"
2) "lyb"
3) (nil)

getset 设置新值返回旧值

GETSET key value
  summary: Set the string value of a key and return its old value
  since: 1.0.0
  group: string

127.0.0.1:6379> getset name 333
"lyb"

getrange 获取字符串的子串

GETRANGE key start end
  summary: Get a substring of the string stored at a key
  since: 2.4.0
  group: string

127.0.0.1:6379> getrange name 2 
(error) ERR wrong number of arguments for 'getrange' command
127.0.0.1:6379> getrange name 2 10
"3"
127.0.0.1:6379> get qq
"456"
127.0.0.1:6379> getrange qq 0 -1
"456"

setrange

SETRANGE key offset value
  summary: Overwrite part of a string at key starting at the specified offset
  since: 2.2.0
  group: string

127.0.0.1:6379> setrange qq 1 ererer
(integer) 7
127.0.0.1:6379> get qq
"4ererer"

strlen 字节长度（汉字是三个）

127.0.0.1:6379> strlen name
(integer) 3

incr 值是数字时一次 +1　　#decr 是 -1

incrby  increment　　指定加多少　　#decrby  decrment   减多少

INCR key
  summary: Increment the integer value of a key by one
  since: 1.0.0
  group: string

127.0.0.1:6379> incr name
(integer) 334
127.0.0.1:6379> incr name
(integer) 335
127.0.0.1:6379> incr name
(integer) 336

incrbyfloat 增加指定浮点数

INCRBYFLOAT key increment
  summary: Increment the float value of a key by the given amount
  since: 2.6.0
  group: string

127.0.0.1:6379> INCRBYFLOAT name 1.2
"337.20000000000000001"
127.0.0.1:6379> INCRBYFLOAT name 1.2
"338.40000000000000002"
127.0.0.1:6379> INCRBYFLOAT name 1.2
"339.60000000000000003"

setbit 和 bitcount：

　　1、统计某天网站的上线的用户数量

　　2、统计某用户访问网站的天数

以1为例：以偏移量为用户的 id

127.0.0.1:6379> set ww ''
OK
127.0.0.1:6379> bitcount ww
(integer) 0

来一个用户，将用户id处的bit设为1

127.0.0.1:6379> setbit ww 5000 1
(integer) 0
127.0.0.1:6379> setbit ww 100 1
(integer) 0
127.0.0.1:6379> setbit ww 100145 1
(integer) 0
127.0.0.1:6379> bitcount ww　　　　#今天有3位用户登录
(integer) 3

查看某些用户是否登录

127.0.0.1:6379> getbit ww 355
(integer) 0
127.0.0.1:6379> getbit ww 5000
(integer) 1

性能：1 byte = 8 bit

　　　　1亿 bit = 12500000 字节 = 12207 k = 12 M

哈希

hset 

HSET key field value
  summary: Set the string value of a hash field
  since: 2.0.0
  group: hash

127.0.0.1:6379> hset dd name lyb
(integer) 1127.0.0.1:6379> hget dd name
"lyb"

hmset 批量设置，hmget 批量获取

HMSET key field value [field value ...]
  summary: Set multiple hash fields to multiple values
  since: 2.0.0
  group: hash

127.0.0.1:6379> hmset dd age 23 addr bj
OK
127.0.0.1:6379> hmget dd age addr name
1) "23"
2) "bj"
3) "lyb"

hgetall 获取所有键-值，hkeys 所有键，hlen 长度

127.0.0.1:6379> hgetall dd
1) "name"
2) "lyb"
3) "age"
4) "23"
5) "addr"
6) "bj"
127.0.0.1:6379> hkeys dd
1) "name"
2) "age"
3) "addr"
127.0.0.1:6379> hlen dd
(integer) 3

hvals 所有值，hexists 键是否存在

127.0.0.1:6379> hvals dd
1) "lyb"
2) "23"
3) "bj"127.0.0.1:6379> hexists dd name
(integer) 1　　#存在
127.0.0.1:6379> hexists dd named
(integer) 0　　#不存在

hdel 删除多个键

HDEL key field [field ...]
  summary: Delete one or more hash fields
  since: 2.0.0
  group: hash

增加

HINCRBY key field increment
  summary: Increment the integer value of a hash field by the given number
  since: 2.0.0
  group: hash

127.0.0.1:6379> help HINCRBYFLOAT

  HINCRBYFLOAT key field increment
  summary: Increment the float value of a hash field by the given amount
  since: 2.6.0
  group: hash

hscan

HSCAN key cursor [MATCH pattern] [COUNT count]
  summary: Incrementally iterate hash fields and associated values
  since: 2.8.0
  group: hash

List列表

lpush ，lrange，lpop

127.0.0.1:6379> lpush mylist a b c　　#等同于 lpush a，lpush b，lpush c，从左开始插入列表
(integer) 3
127.0.0.1:6379> lrange mylist 0 -1
1) "c"
2) "b"
3) "a"
127.0.0.1:6379> lpop mylist
"c"
127.0.0.1:6379> lpop mylist
"b"
127.0.0.1:6379> lpop mylist
"a"
127.0.0.1:6379> lpop mylist
(nil)

rpush

127.0.0.1:6379> rpush mylist d e
(integer) 5
127.0.0.1:6379> lrange mylist 0 -1
1) "c"
2) "b"
3) "a"
4) "d"
5) "e"

lpushx 列表存在才添加

LPUSHX key value
  summary: Prepend a value to a list, only if the list exists
  since: 2.2.0
  group: list

llen

LLEN key
  summary: Get the length of a list
  since: 1.0.0
  group: list

linsert

LINSERT key BEFORE|AFTER pivot value
  summary: Insert an element before or after another element in a list
  since: 2.2.0
  group: list

127.0.0.1:6379> lrange mylist 0 -1
1) "f"
2) "c"
3) "b"
4) "a"
5) "d"
6) "e"
127.0.0.1:6379> linsert mylist before 2 charu　　#值不存在返回-1
(integer) -1
127.0.0.1:6379> lrange mylist 0 -1
1) "f"
2) "c"
3) "b"
4) "a"
5) "d"
6) "e"
127.0.0.1:6379> linsert mylist after b charu
(integer) 7　　#成功返回最终长度
127.0.0.1:6379> lrange mylist 0 -1
1) "f"
2) "c"
3) "b"
4) "charu"
5) "a"
6) "d"
7) "e"

lset

LSET key index value
  summary: Set the value of an element in a list by its index
  since: 1.0.0
  group: list

127.0.0.1:6379> lset mylist 10 3
(error) ERR index out of range
127.0.0.1:6379> lset mylist 5 3
OK
127.0.0.1:6379> lrange mylist 0 -1
1) "f"
2) "c"
3) "b"
4) "charu"
5) "a"
6) "3"
7) "e"

lrem

LREM key count value
  summary: Remove elements from a list
  since: 1.0.0
  group: list

127.0.0.1:6379> lrange mylist 0 -1
1) "a"
2) "f"
3) "f"
4) "c"
5) "b"
6) "charu"
7) "a"
8) "3"
9) "e"
127.0.0.1:6379> lrem mylist  1 a
(integer) 1
127.0.0.1:6379> lrange mylist 0 -1
1) "f"
2) "f"
3) "c"
4) "b"
5) "charu"
6) "a"
7) "3"
8) "e"
127.0.0.1:6379> lrem mylist  2 f
(integer) 2
127.0.0.1:6379> lrange mylist 0 -1
1) "c"
2) "b"
3) "charu"
4) "a"
5) "3"
6) "e"

lpop

LPOP key
  summary: Remove and get the first element in a list
  since: 1.0.0
  group: list

lindex

LINDEX key index
  summary: Get an element from a list by its index
  since: 1.0.0
  group: list

ltrim

LTRIM key start stop
  summary: Trim a list to the specified range
  since: 1.0.0
  group: list
127.0.0.1:6379> lrange mylist 0 -1
1) "c"
2) "b"
3) "charu"
4) "a"
5) "3"
6) "e"
127.0.0.1:6379> ltrim mylist 2 5
OK
127.0.0.1:6379> lrange mylist 0 -1
1) "charu"
2) "a"
3) "3"
4) "e"

rpoplpush

RPOPLPUSH source destination
  summary: Remove the last element in a list, prepend it to another list and return it
  since: 1.2.0
  group: list

127.0.0.1:6379> lrange mylist 0 -1
1) "charu"
2) "a"
3) "3"
4) "e"
127.0.0.1:6379> lpush my 123 445
(integer) 2
127.0.0.1:6379> RPOPLPUSH mylist my
"e"
127.0.0.1:6379> lrange mylist 0 -1
1) "charu"
2) "a"
3) "3"
127.0.0.1:6379> lrange my 0 -1
1) "e"
2) "445"
3) "123"

blpop

BLPOP key [key ...] timeout
  summary: Remove and get the first element in a list, or block until one is available
  since: 2.0.0
  group: list

127.0.0.1:6379> blpop my 10
1) "my"
2) "e"
127.0.0.1:6379> blpop my 10
1) "my"
2) "445"
127.0.0.1:6379> blpop my 10
1) "my"
2) "123"
127.0.0.1:6379> blpop my 10
(nil)
(10.07s)