20220527初学Redis之概述+安装+基本指令了解_refusing to operate on alias name or linked unit f-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_45707639/article/details/125007169

本文介绍了Redis，一个键值型的NoSQL数据库，强调其低延迟、速度快的特性，并提供了在Linux系统上的安装步骤，包括如何后台启动及配置服务。此外，还概述了Redis的一些基本命令，如SELECT、GET、SET、DEL、MSET/MGET、EXISTS、EXPIRE、INCR/INCRBY、SETNX/SETEX。

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SQL (关系型数据库)VS NoSQL（非关系型数据库）

SQL	NoSQL
RELATIONAL DATABASE MANAGEMENT SYSTEM (RDBMS)	Non-relational or distributed database system.
These databases have fixed or static or predefined schema	They have dynamic schema
These databases are not suited for hierarchical data storage.	These databases are best suited for hierarchical data storage.
These databases are best suited for complex queries	These databases are not so good for complex queries
Vertically Scalable	Horizontally scalable
Follows ACID property	Follows CAP(consistency, availability, partition tolerance)

Redis=Remote Dictionary Server 远程词典服务器

2009年开发的，键值型NoSQL数据库.

特征：

键值型
单线程，每个命令具有原子性
低延迟，速度快（原因：基于内存，IO多路复用，良好的编码）
支持数据持久化
支持主从集群，分片集群
支持多语言客户端

Installation（base on Linux System）：

yum install -y gcc tcl

上传/usr/local/src目录

解压

tar -zxvf redis.tar.gz

cd redies

运行编译命令：

make && make install

运行

redis-server

设置后台启动需配置redis.conf

backup conf file to avoid any accident:

cp redis.conf redis.conf.bck

修改如下参数:

#default 127.0.0.1 can only allow localhost access,use 0.0.0.0 can allow any other IP wants to access

bind 0.0.0.0      

# yes to make background service avaiable
daemonize yes

#password for access to Redis
requirepass *******


#easy to understand.___why6379:6379 在是手机按键上字母 MERZ 对应的号码。 而 MERZ 取自意大利歌女 Alessia Merz 的名字。 MERZ长期以来被 Redis 作者 antirez 及其朋友当作愚蠢的代名词。 后来 Redis 作者在开发 Redis 时就选用了这个端口~~
port 6379

#workspace,default current catlogs you use command redis-server,will restore logs and persitence files here.
dir .

# database qty, setting to "1" only use only 1 base.By default,there are 16 pcs of bases marking from 0 to 15.
databses 1

#The max memory to allow redis to use
maxmemory 512mb

#log names,defult as null and not recording the logs.Can record once set a name
logfile "redis.log"

quick to find config name：

#/configname
#eg:
/daemonize

to start Redis:

# enter the root of redis
cd /user/local/src/redis
# start
redis-server redis.conf

to see the status of redis

ps -ef | grep redis

to kill/end the process

kill -9 PID

kill -9中，9代表的就是9号信号，带有强制执行的意思，它告诉进程：“无论你现在在做什么，立刻停止”。

Make redis start with System

create a service file firstly

vi /etc/systemd/system/redis.service

add those content to the file

[Unit]
Description=redis-server
After=network.target

[Service] 
Type=forking
ExecStart=/usr/local/bin/redis-server/usr/local/src/redis-6.2.6/redis.conf
PrivateTmp=true

[Install]
WantedBy=multi-user.target

reload the system service

#make background service reload
systemctl daemon-reload

#then to start
systemctl start redis

#to check the status of redis
systemctl status redis

#to stop redis
systemctl stop redis

finally to enable redis to start with system

systemctl enable redis
#then to start redis
systemctl start redis

Redis命令行客户端(example:login)

#for login:

redis-cli [options][commands]

#redis-cli -h -p
#redis-cli -h 127.0.0.1 -p 6379 -a ******

COMMAND

SELECT——Select database

SELECT 0~15

GET——To get value via KEY

GET $KEY

set——Set KEY-VALUE:

set $KEY $VALUE
#set name jack
# it means that key is "name", and value is "jack"

help——get help gude，we can use this command to know how to use the command

help [@command]
#to add a # to see details
help @**

KEYS——search by KEYS name

KEYS *
KEYS a*
KEYS *a*
#it's not recommended to use KEYS to query in production environment.

DEL——to delet a key

DEL $KEY

MSET——to muti-add keys

MSET $KEY1 $VALUE1 $KEY2 $VALUE2 $KEY3 $VALUE3
#this command will reture the qty of successfull result.

MGET——to muti-get keys

MGET $KEY1 $KEY2 $KEY3

EXISTS——to judge if the key exist

EXISTS $KEY
#will return 1 or 0 ,0 represents $KEY not exists, 1 represents $KEY exists actually

EXPIRE——to set a timelimit to make a KEY out of date and removed. we usually use “TTL” command to see the rest lifetime for a key.

EXPIRE $KEY $SECONDS
#EXPIRE name 20
TTL $KEY
#to see the key's life time. "-1" means forever exist;"-2" means removed already;

INCR & INCRBY——defaultly increase 1, use incrby to set value to incrase

#age will increase 1
incr age

#age will increase 2
incrby age 2

**SETNX **&SETX ——set a key-value if only when the key doesn’t exist,SETX means set a key-value with lifetime

SETNX $KEY $VALUE

SETEX $KEY $SECONDS $VALUE
#SETEX name 20 KKK  ,means a key"name",value"KKK",expire 20s

==> set $KEY $VALUE ex $SECONDS

PS: 以·tar.gz为后缀的文件是一种压缩文件，在Linux和macOS下常见，Linux和macOS都可以直接解压使用这种压缩文件。eg: tar -zxf redis-6.0.8.tar.gz