Redis Foundation

One 、Redis brief introduction
Redis Is a high-performance key-value database

Two 、Redis Characteristics
Support data persistence
Rich data types

3、 ... and 、redis data type

string（ character string ）,hash（ Hash ）,list（ list ）,set（ aggregate ） And zset(sorted set： Ordered set )

1、string（ character string ）

# Set up 
SET runoob " Novice tutorial "

# obtain 
GET runoob

2、Hash（ Hash ）

# Set up 
HMSET runoob field1 "Hello" field2 "World"

# obtain 
HGET runoob field1
HGET runoob field2

3、List（ list ）

# Set up 
lpush runoob redis
lpush runoob mongodb
lpush runoob rabbitmq

# obtain 
redis 127.0.0.1:6379> lrange runoob 0 10
1) "rabbitmq"
2) "mongodb"
3) "redis"

4、Set（ aggregate ）

# grammar 
sadd key member

# Set up 
sadd runoob redis
sadd runoob mongodb
sadd runoob rabbitmq
sadd runoob rabbitmq

# obtain 
redis 127.0.0.1:6379> smembers runoob

1) "redis"
2) "rabbitmq"
3) "mongodb"

5、zset(sorted set： Ordered set )

# grammar 
zadd key score member 

# Set up 
zadd runoob 0 redis
zadd runoob 0 mongodb
zadd runoob 0 rabbitmq
zadd runoob 0 rabbitmq

# obtain 
redis 127.0.0.1:6379> ZRANGEBYSCORE runoob 0 1000
1) "mongodb"
2) "rabbitmq"
3) "redis"

notes ： Delete use DEL key

Four 、Redis Publish subscribe
Redis Publish subscribe (pub/sub) It's a message communication mode ： sender (pub) Send a message , subscriber (sub) receive messages .

5、 ... and 、Redis Business

1、 A transaction goes through the following three stages from the beginning to the execution ：
Start business .
Order to join the team .
Perform transactions .

2、 example
Start with MULTI Start a transaction , Then queue multiple commands into the transaction , Finally by EXEC Command triggers transaction , Execute all the commands in the transaction

redis 127.0.0.1:6379> MULTI
OK

redis 127.0.0.1:6379> SET book-name "Mastering C++ in 21 days"
QUEUED

redis 127.0.0.1:6379> GET book-name
QUEUED

redis 127.0.0.1:6379> SADD tag "C++" "Programming" "Mastering Series"
QUEUED

redis 127.0.0.1:6379> SMEMBERS tag
QUEUED

redis 127.0.0.1:6379> EXEC
1) OK
2) "Mastering C++ in 21 days"
3) (integer) 3
4) 1) "Mastering Series"
   2) "C++"
   3) "Programming"

6、 ... and 、Redis Stream
Redis Stream It is mainly used for message queuing （MQ,Message Queue）,Redis There is one in itself Redis Publish subscribe (pub/sub) To realize the function of message queuing , But it has a drawback that messages are not persistent , If there is a network disconnect 、Redis Downtime, etc , The message will be discarded .

Simply put, publish subscribe (pub/sub) You can distribute messages , But we can't record historical information .

and Redis Stream It provides message persistence and primary / secondary replication functions , Any client can access data at any time , And remember the location of each client's access , It also ensures that the message is not lost .

Message queuing related commands ：
XADD - Add the message to the end
XTRIM - Pruning the convection , Limit length
XDEL - removal message
XLEN - Gets the number of elements contained in the stream , The message length
XRANGE - Get message list , Will automatically filter deleted messages
XREVRANGE - Get the message list in reverse ,ID From big to small
XREAD - Get a list of messages in a blocking or non blocking way

Consumer group related orders ：
XGROUP CREATE - Create consumer groups
XREADGROUP GROUP - Read messages from consumer groups
XACK - Mark the message as " Disposed of "
XGROUP SETID - Set up a new last delivery message for the consumer group ID
XGROUP DELCONSUMER - Delete consumer
XGROUP DESTROY - Delete consumer group
XPENDING - Displays information about the message to be processed
XCLAIM - Transfer ownership of messages
XINFO - View information about streams and consumer groups ;
XINFO GROUPS - Print information about consumer groups ;
XINFO STREAM - Print stream information

7、 ... and 、Redis Data backup and recovery
1、 Backup
Redis SAVE Command to create a backup of the current database

example ：

redis 127.0.0.1:6379> SAVE 
OK

The order will be in redis Create... In the installation directory dump.rdb file .

2、 recovery

If you need to recover data , Just back up the files (dump.rdb) Move to redis Install the directory and start the service . obtain redis The directory can be used CONFIG command , As shown below ：

redis 127.0.0.1:6379> CONFIG GET dir
1) "dir"
2) "/usr/local/redis/bin"

The above order CONFIG GET dir Output redis Installation directory is /usr/local/redis/bin.

8、 ... and 、Redis Security

1、 example
We can check whether password verification is set through the following command ：

127.0.0.1:6379> CONFIG get requirepass
1) "requirepass"
2) ""

By default requirepass Parameter is empty , This means that you can connect to... Without password verification redis service .

You can modify this parameter with the following command ：

127.0.0.1:6379> CONFIG set requirepass "runoob"
OK
127.0.0.1:6379> CONFIG get requirepass
1) "requirepass"
2) "runoob"

After setting the password , Client connection redis The service needs password verification , Otherwise, the command cannot be executed .

grammar
AUTH The basic syntax of the command is as follows ：

127.0.0.1:6379> AUTH password
 example 
127.0.0.1:6379> AUTH "runoob"
OK
127.0.0.1:6379> SET mykey "Test value"
OK
127.0.0.1:6379> GET mykey
"Test value"

Nine 、Redis Pipeline technology
Redis It's a client based - Server model and request / In response to the protocol TCP service . This means that normally a request follows these steps ：

The client sends a query request to the server , And monitor Socket return , Usually in blocking mode , Waiting for the server to respond .
The server handles commands , And return the result to the client .

Redis Pipeline technology can be used when the server is not responding , The client can continue to send requests to the server , And finally read all the server's responses at once .

Advantages of Pipeline Technology ： The most significant advantage of pipeline technology is the improvement of redis Service performance .

Ten 、Redis Partition
Partitioning is dividing data into multiple Redis The process of the instance , So each instance only saves key A subset of .

11、 ... and 、 other
Redis Queue real-time and non real-time ： Real time and non real time are mainly aimed at consumers , Message producers produce messages after ,Redis These messages are stored in the queue , When to consume is our concern , Non real time means , At the back end, there is a rotation service to get messages from the queue regularly , This has a certain delay ; Real time means building on the consumer side Tcp A long connection , When the queue has data, consume it immediately , When there is no data, the thread is in a suspended waiting state ！