New to Redis

Redis（Remote Dictionary Server ), Remote dictionary service , Is an open source use ANSI C Language writing 、 Support network 、 Log type that can be memory based or persistent 、Key-Value database , And provide multilingual API

Basic data type

	- String
	- Hash
	- List
	- Set
	- Zset

Basic commands

select 1 # Select database  16 A database 
DBSIZE # View the database size 
keys * # Look at all the keys 
flushdb # Clear current database 
flushall # Clear all databases 

Key Basic command ：

set key val
get key
del key
rename key newkey
expire key 10 #10 Seconds expired 
exists key # Whether there is key
type key # View type 
ttl key # View expiration time 

String

append key xxx # Additional content 
strlen key # Look at string length 
incr key # Self increasing 1
incrby key n # Self increasing n
decr key # Self reduction n
decrby key n # Self reduction n
getrange key start end # Gets the specified string 
setrange key offset xx # Replace 
setex key 10 val # Set expiration time  
setnx key val # If it doesn't exist, set 
mset mget # The batch   Atomicity 
getset key val # Get first and then set 

Hash

hset user name zhangsan # Set up 
hget user name # obtain 
hmset user name zhangsan age 15 # The batch 
hmget user name age # The batch 
hgetall user # Get all the fields 
hdel user name # Delete a field 
hexists user age # Check whether a field exists 
hkeys user # Get all the fields key
hvals user # Get all the fields value
hlen user # Get the number of fields 

List

lpush # Insert one or more values into the list header 
lpop user # Eject and remove 
rpush # Add one or more values... To the list 
rpop # Remove the last element of the list , The return value is the removed element .
lrange 0 -1 # Get all the elements 
lrem user 1 zhangsan # Delete 
lset user 0 "bar"

Set

sadd # Add one or more members to the collection 
scard key # Get the number of members of the collection 
sismember ket member # Judge  member  Is the element a collection  key  Members of 
smembers key # Returns all members of the collection 
srem # Remove one or more members of the collection 
spop # Remove and return a random element from the collection 
srandmember key [count] # Returns one or more random numbers in a set 

Redis Business

Redis Transactions can execute more than one command at a time , And there are three important guarantees ：

• Bulk operation is sending EXEC The command is put into the queue cache .
• received EXEC Enter transaction execution after command , The execution of any command in the transaction failed , The rest of the orders are still being carried out .
• In the transaction execution process , Command requests submitted by other clients will not be inserted into the transaction execution command sequence .

A transaction goes through the following three stages from the beginning to the execution ：

• Start business .
• Order to join the team .
• Perform transactions .

It starts 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

Single Redis The execution of orders is atomic , but Redis There is no mechanism to maintain atomicity in transactions , therefore Redis The execution of a transaction is not atomic .

Transactions can be understood as a packaged batch execution script , But batch instructions are not atomic operations , The failure of an instruction in the middle will not result in the rollback of the previous instruction , It will not cause subsequent instructions not to do .

Persistence strategy

1. RDB（ Default ）
2. AOF