centos7 yum installation redis and what are the common commands

What is redis

Redis is a memory-based data structure storage, durable log-type, Key-Value database. When a site using a relational database reaches a certain amount of concurrency, there will often be a bottleneck in disk IO. At this time, working with redis has certain advantages because it has the following characteristics:

• Based on memory operation, high concurrent reading and writing;

• supports distribution and can theoretically be infinitely expanded;

• Rich data types;

• Persistence, can be written to disk regularly;

Application scenarios

• Cache "hot spots" "Data (high-frequency reading, low-frequency writing)

• Counter, current limiter

• Message queue system (publish and subscribe, ranking list)

• Distributed lock, shared session, queue

Data type:

The data types provided by Redis are mainly divided into 5 types Own types and a custom type. These 5 own types include:
String type, Hash type, List type, Set type and Sorted type Set) collection type.

String type:

It can store strings, pictures, videos and other types. The maximum length supports 512M. Operation commands, such as:

• GET/MGET

• SET/SETEX/MSET/MSETNX

• INCR/DECR

• GETSET

• DEL

Hash type:

This type is a map composed of fields and associated values. Among them, field and value are both of string type. The operation command is as follows:

• HGET/HMGET/HGETALL

• ##HSET/HMSET/HSETNX

• HEXISTS/HLEN

• HKEYS/HDEL

##HVALS

• ##List type:

This type is a collection of string elements sorted in insertion order, implemented based on a double linked list. The operation command is as follows:

LPUSH/LPUSHX/LPOP/RPUSH/RPUSHX/RPOP/LINSERT/LSET

• ##LINDEX/LRANGE

• LLEN/LTRIM

• Set type:

The Set type is an unordered collection. The biggest difference between it and the List type is: The elements in the set have no order and the elements are unique.

The bottom layer of the Set type is implemented through a hash table, and its operation command is:

SADD/SPOP/SMOVE/SCARD

• SINTER/SDIFF/SDIFFSTORE/SUNION

• The Set type is mainly used: In some scenarios, such as social scenarios, through intersection, union and difference operations, the Set type can It is very convenient to find social relationships such as mutual friends, common concerns and common preferences.

Sequential set type:

ZSet is an ordered set type. Each element is associated with a double type fractional weight. This weight is used to determine the size of the members in the set. to large order.

Like the Set type, its bottom layer is also implemented through a hash table. ZSet command:

ZADD/ZPOP/ZMOVE/ZCARD/ZCOUNT

• ZINTER/ZDIFF/ZDIFFSTORE/ZUNION

• Quick installation

  yum install redis

Direct yum installation of redis is not the latest version, you can install the latest Redis through Remi.

• yum install -y epel-release
yum install -y http://rpms.remirepo.net/enterprise/remi-release-7.rpm

Remi's RPM repository maintains the latest and additional packages. It is best to install EPEL first, because the Remi repository depends on it.

Use the following command to install the latest version of Redis:

• yum –enablerepo=remi install redis

After the installation is completed, you can start the redis service and start it automatically after booting up

• ##systemctl start redis

  systemctl enable redis

View the redis version:

• redis-cli –version

redis defaults to 127.0. 0.1 access, remember to set a password when enabling remote login! ! !

Commonly used commands

Commonly used commands during testing

redis客户端连接：
    本地连接：redis-cli
    远程连接：redis-cli -h host -p port -a password

PING  查看服务是否运行

SELECT index  切换到指定的数据库
	select 0  选择第一个库

keys *  获取所有的key

flush db  清除指定库
flushall  清除所有

• Several types are commonly used Command

string
    set key value
    get key
hash
    hset myhash name cxx
    hget myhash name
list
    lpush mylist a b c  左插入
    rpush mylist x y z  右插入
    lrange mylist 0 -1  数据集合
    lpop mylist  弹出元素
    rpop mylist  弹出元素
    llen mylist  长度
    lrem mylist count value  删除
set
    sadd myset redis 
    smembers myset       数据集合
    srem myset set1         删除
zset
    zadd zset 1 one
    zadd zset 2 two
    zadd zset 3 three

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