Redis learning

1. What is? nosql

NoSQL(NoSQL = Not Only SQL ), Means against SQL motion , Is a new database revolutionary movement ,2000 It was proposed years ago , To 2009 The annual trend is rising . It refers to the use of non relational data storage , Relative to the overwhelming use of relational databases , This concept is undoubtedly an injection of new thinking .
With the Internet web2.0 The rise of websites , Traditional relational databases are coping web2.0 Website , Especially large scale and high concurrency SNS Type of web2.0 Pure dynamic website has appeared to be powerless , A lot of insurmountable problems were exposed , The non-relational database has developed rapidly due to its own characteristics .NoSQL The emergence of database is to solve the challenge of large data sets and multiple data types , Especially big data application problem .

2. NoSQL Characteristics of ？

NoSQL yes key-value stored , Unlike traditional relational databases , Not necessarily following some basic requirements of traditional databases , For example, follow SQL standard 、ACID attribute 、 Table structure and so on .
This kind of database mainly has the following characteristics ：

• Non relational 、 Distributed 、 Open source 、 Horizontally scalable processing of huge amounts of data
• Broke the performance bottleneck
• Read and write data with high concurrency
• Efficient storage and access of massive data, high scalability and high availability of data

3. What is? Redis？

Redis It's an open source , advanced key-value Storage . It is often referred to as a data structure server , Because keys can contain string（ character string ）、hash（ Hash ）、list（ Linked list ）、set（ aggregate ） and zset（sorted-set– Ordered set ）. These data types support push/pop、add/remove And take intersection, union and difference sets and more abundant operations .
Redis and Memcached similar , It supports storage value There are more types , And memcached equally , To ensure efficiency , The data is cached in memory , The difference is that Redis Periodically, updated data is written to disk or changes are written to an appended log file , And on this basis to achieve master-slave( Master-slave ) Sync .

4.Redis Installation and deployment

Redis  The official website of ：http://redis.io

 Download installation package ：
# wget http://download.redis.io/releases/redis-2.8.6.tar.gz
 Compilation and installation ：
# tar –zxvf redis-2.8.6.tar.gz # cd redis-2.8.6
# make
# make PREFIX=/usr/local/redis install
 Specify the installation location , If the installation location is not specified  PREFIX=/usr/local/redis, be  make install  Will be able to  redis  The installation to /usr/local/bin/ Under the table of contents 
# mkdir /usr/local/redis/etc
# cp ./redis.conf /usr/local/redis/etc/

 Copy Redis  Configuration file to /usr/local/redis/etc/ Next , Easy to manage .

 Modify the configuration file ：
# vi /usr/local/redis/etc/redis.conf
daemonize no	 It is amended as follows  yes	# Background start 

 Start the service ：
# /usr/local/redis/bin/redis-server  The configuration file 
 Configuration file location must be specified , Otherwise, a warning will be prompted 

 Client connection ：
/usr/local/redis/bin/redis-cli
-h	IP：	 Connect the specified  redis  The server 
-p	6379：	 Appoint  redis  The port of the server 
-a	 password ：	 Log in with password 
-n	 Database number ：  Specify which database to connect to 
--raw：	redis  Support to store Chinese 

 stop it  Redis：
# /usr/local/redis/bin/redis-cli shutdown
 or 
# pkill -9 redis

5.Redis Common commands

1) string Type and operation

string Is the simplest type , One key Corresponding to one value,string Type is binary safe .redis Of string Can contain any data .
1.set： Set up key The corresponding value is string type
for example ： Let's add a name=atguigu The key value of corresponds to
redis127.0.0.1:6379>set name atguigu
2.setnx： Set up key The corresponding value is string type , If key Already exist , return 0,nx yes not exist It means
3.get： obtain key Corresponding string value , If key There is no return nil
4.mset & mget Set and get multiple key value pairs at the same time
5.incrby： Yes key The value of plus （ Specify the value ） operation , And return the new value
6.del： Delete a created key

2)hash Type and operation

Redis hash It's a string Type of field（ Field ） and value Mapping table , Its addition 、 Delete operations are 0(1) Average ;hash Ideal for storing objects , Instead of saving each field of an object as a single string type , Store an object in hash Type takes up less memory , And it can be more convenient to access the entire object .
1.hset： Set up hash field For the specified value , If key non-existent , First create . for example ： by num1 Create a table called name Field （key）, The key value is liuchuan redis127.0.0.1:6379>hset num1 name liuchuan

2.hget、hmset、hmget The meaning is similar to that of
3.hdel： Delete a key value pair in the formulation table
4.hgetall： List all key value pairs in the table

3)list Type and operation

list Is a linked list structure , The main functions are push、pop、 Get all the values in a range, and so on , In operation key The name of the list .Redis Of list Type is actually a sub element string Double linked list of type . We can go through push、pop Operation adds or deletes elements from the head or tail of the linked list .

1.lpush： stay key Corresponding list Add string elements to the header of .redis127.0.0.1:6379>lpush zhangsan zhangsan redis127.0.0.1:6379>lpush zhangsan 18
2.lrange： Get the elements of the specified range from the specified linked list redis127.0.0.1:6379>lrange zhangsan 0 -1
0 -1： This range represents all elements , It means from beginning to end
3.lpush、rpush、lpop、rpop、lrange See the figure for details

4)Set Type and operation

set Is a collection , He is string Unordered collection of type .Set It's through hash table Realized , Pair set 、 intersection 、 Difference set . Through these operations, we can realize friend recommendation and blog Of tag function . Set cannot have duplicate values .

1.sadd： Add one or more elements to the collection redis127.0.0.1:6379>sadd mset 1 2 3 4
2.smembers： Get all the elements in the collection redis127.0.0.1:6379> smembers mset
3.srem： Deletes the specified element or elements from the collection
4.spop： Randomly delete an element from the collection , And back to
5.scard： Get the number of elements in the collection
6.sdiff： Back to the assembly 1 And assemble 2 The difference between the set . To gather 1 Mainly
redis127.0.0.1:6379>sdiff mset1 mset2
7.sinter： Get the intersection of two sets
8.sunion： Get the union of the specified set

5)zset Type and operation

zset yes set An updated version of , It's in set Add a sequence attribute based on the , This attribute can be specified when adding modification elements , After each assignment ,zset Automatically reorder to the new value . It can be understood as having two columns mysql surface , A list of stored value, A sequence of storage . In operation key Understood as a zset Name .

1. zadd： Add elements to a specified ordered set , Each element will have a corresponding score . You can specify multiple points
   / Member groups . If a specified member is already in the corresponding ordered set , Then the score will be updated to the latest , And the member will be relocated to the right place , To make sure the assembly is in order . The value of the fraction must be a string representing the number .redis127.0.0.1:6379>zadd zset 2 zhangsan 1 lisi 1 wangwu
2. zrange： Return to the ordered set , Specify the members in the interval . Among them, the members follow score（ fraction ） Rank values from small to large . Have the same score The members of values are arranged in dictionary order .
   redis127.0.0.1:6379>zrange zset 0 -1 withscores
   notes : withscores While returning the elements in the collection , Returns its score （score）
3. zrem： Delete the specified value in the ordered set redis127.0.0.1:6379>zrem zset zhangsan
4. zcard： Returns the number of elements in an ordered set

6) Other relevant orders

1. keys： Find the specified key by key name . Support for wildcards （* ? etc. ） redis127.0.0.1:6379>keys h*llo
2. exists： Confirm whether a key exists （1 Indicates presence ）
3. del： Delete a key （ Universal ）
4. expire： Set a key （ Already exists ） The expiration time of , If the key has expired , Will be automatically deleted
5. ttl： In seconds , Returns the remaining valid time of the specified key
   When key When there is no , return -2 .
   When key When the remaining lifetime exists but is not set , return -1 . otherwise , In seconds , return key The remaining lifetime of .
6. select： Select a database , The default database to connect to is 0, Can support a total of 16 A database . In the configuration file , adopt
   databases 16 Keyword definition .
7. move： Move the key of the current database to the specified database
8. type： Return the type of key
9. dbsize： Returns the number of keys in the current library （ All types ）
10. save： Save all the data . Rarely used directly in a production environment SAVE command , Because it blocks all client requests , have access to BGSAVE Command instead of . If in BGSAVE When an error occurs in the sub process of saving data of the command , use SAVE The command to save the latest data is the last resort .
11. info： Get the details of the server
12. config get： obtain redis Parameters in the server configuration file . Support for wildcards
13. flushdb： Delete all data in the current database
14. flushall： Delete all data in all databases

6. Redis Advanced applications

1) Password protection

1、 Modify the configuration file 
# vi /usr/local/redis/etc/redis.conf requirepass 123456
2、 restart  redis # pkill redis
# …/bin/redis-server …/etc/redis.conf
3、 Client login 
# …/bin/redis-cli -a 123456
 Or in interactive mode 【auth  password 】 command 

2) Master slave synchronization

Redis Master slave replication process ：

• Slave And master Establishing a connection , send out sync Synchronization command
• Master A background process will be started , Save the database snapshot to a file , meanwhile master The main process will start collecting new write commands and caching .
• After the background is saved , Send this file to slave
• Slave Save this file to your hard disk

1. The master server can set the password for itself （iptables&SELinux  close ）
2. Modify the configuration file from the server , Used to connect to the main server 
 The old version ：
 from ：
slaveof <masterip> <msterport>	# Of the main server  IP  And port 
masterauth <masterpass>	# The password for the primary server ( The master server should set the password )
 The new version  redis 5.*  above ：  Lord ：
 find  bind 127.0.0.1  Comment out , Or change it to native  IP  Address ( restart )  from ：
replicaof	<masterip> <msterport>	# Of the main server  IP  And port 
masterauth <masterpass>	# The password for the primary server ( The master server should set the password )
3. Restart the slave server , Then test （ It can be done by  info  Command to get the current server identity type ）

Reading the configuration file, at line 88 >>> 'protected-mode no' Bad direc

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3) Data persistence

RDB

snapshotting（ snapshot ）– Default mode

RDB Persistence allows you to store snapshots of your data at specified intervals . It's the default way to persist . This method is to write the data in memory to the binary file in the form of snapshot , The default filename is dump.rdb. This persistence is called snapshot snapshotting（ snapshot ）.

After that 900 Seconds and there are 1 individual key It has changed It will trigger save action # After that 300 Seconds and there are 10 individual key It has changed It will trigger save action # After that 60 Seconds and at least 10000 individual key It has changed It will also trigger save action

Conclusion ： stay redis.conf In file dir ./ Defines the storage location of database files , The default is the current directory . So every time you restart redis
The location of the service is different , Will generate new dump.rdb file ; It is recommended to modify the location where the snapshot file is saved when the server is set up .

RDB Starting mode  —— save Instruction related configuration 
 dbfilename dump.rdb
 explain ： Set the local database file name , The default value is  dump.rdb
 Experience ： Usually set to dump- Port number .rdb
 dir
 explain ： Set up storage .rdb
 Experience ： Usually set to save 
 rdbcompression yes
 explain ： Store settings locally 
 Experience ： Usually, it defaults to open 
 rdbchecksum yes
, The default is  yes, use  LZF  Compress 
 Set to no, Can save  CPU  The elapsed time , But it makes the stored files bigger （ huge ）
 explain ： Set whether to RDB File format verification , The verification process is carried out in the process of writing and reading files 
 Experience ： It is usually on by default , If set to no, It can save the reading and writing process about 10% Time consuming , However, there is a certain risk of data corruption 

AOF

append-only file（ abbreviation aof）

Use AOF Will let you Redis More durable : You can use different persistence strategies ： Back up every time you write 、 Backups per second 、 No backup . Use the default backup per second policy ,Redis The performance is still very good ( The backup is processed by the background thread , The main thread will try its best to handle client requests ), In case of failure , The most you lose 1 Second data .

 open  redis.conf  Profile on  AOF  Persistence 
appendonly no
 Default not to use  AOF  Persistence （450  That's ok ） take no  Change to  yes.# appendfsync always
 There are write operations , Write to disk immediately . The slowest efficiency , But the safest 
appendfsync everysec
 Default , Write to disk once per second .
 appendfsync no
 Don't make  AOF  Backup , Give the data to the operating system for processing . The fastest , The least safe 
 test ： restart  redis  service , Sign in  client  Add a key value , Quit and  ls  Command to check whether  appendonly.aof.

 It can be used  cat  see .

4) Sentinel mode

sentry (sentinel) It's a distributed system , It's used to do... On each server in the master-slave structure
monitor , When there is a failure, the voting mechanism is used to select a new one master And put all slave Connect to the new master.

The role of a sentry

1. monitor
   Keep checking master and slave Is it working .master Survival tests 、master And slave Operation detection
2. notice （ remind ）
   When there is a problem with the monitored server , To the other （ The sentry room , client ） Sending notice .
3. Automatic failover
   To break off master And with slave Connect , Pick one slave As master, Will others slave Connect to the new master, And inform the client of the new server address

https://blog.csdn.net/qq_44299529/article/details/123256648

mysql And redis combination

 link ：https://pan.baidu.com/s/14qXfId2sTAUB2LycFk2guQ?pwd=0i0t 
 Extraction code ：0i0t 
-- From Baidu network disk super member V4 The share of