1. Definition

Redis Is a high-performance key-value database ,key It's a string type .

2. Core features

Redis The server program adopts the single process model to process the client's request . The response to read-write time is through epoll Function to do this .

3. data type

The type of key is string

There are five types of values :   character string string, Hash hash, list list, unordered set set; Ordered set zset

3.1 string type

1. brief introduction

character string (string) yes Redis Most basic types , Can be stored String,Integer,Float Data of type , Even binary data , The maximum size of a string is 512M

2.set command

set key value

If the key doesn't exist , Is to add

If the bond exists , Is to modify

Set expiration time （setex key Expiration time / The unit is in seconds   value ）

setex   name2  3  wangwu

Set multiple key value pairs

mset key1 value1 key2 value2 key3 value3

Additional value

append key value

3.get command

Get a single value

get key1

Get multiple values

mget key1 key2

4.del command

Delete a key

del key1

Delete multiple keys

del key1 key2

5.keys command ( Lookup key )

Find a key

keys Key name

check look for All keys

keys *

6.exists command ( Judge whether the key exists )

If there is a return 1, There is no return 0

exists key

7.type command ( View the type of the value corresponding to the key )

type key

8.expire command ( Set key expiration time )

expire key Number of seconds

expire name 5

9.TTL command ( View key effective time )

TTL key

In seconds , Return to a given key The remaining lifetime of (TTL, time to live).

Return value

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 .

3.2 list type

1. brief introduction

Values in the list (value) Type is string

character string List, The underlying implementation is not an array , It's a linked list , That is to say, insert a new element in the head and tail , Its time complexity is constant ; The disadvantage is ： Element positioning is slower than array positioning

2. add to

Insert values from the left :

lpush key value1 value2

Insert values from the right :

rpush key value1 value2

3. obtain

The index starts on the left , The index of the first value is 0

The index can be negative , It means counting from the tail , Such as -1 Represents the last value

start,stop For the index to get the value

grammar （ Returns the value of the specified range in the list ）

lrange key start stop

Get all the values in the list

lrange  key  0  -1

Get the last value from the third element

lrange  key  2  -1

4. modify

The index starts on the left , The index of the first value is 0

The index can be negative , From the tail ,-1 Represents the last value

grammar （ Set the value of the specified index position ）

lset key index value

5. Delete

Put the list before count The value of the second occurrence is removed

count>0: Delete from beginning to end ;count<0: Delete... From tail to head ;count=0: Delete all values

grammar （ Delete the specified value ）

lrem key count value

Query list

lrange born2 0 -1

Delete... From the right side of the key list 1 individual 2

lrem born2 -1 2

Delete... From the left side of the key list 2 individual 2

lrem born2 2 2

3.3 set type

1. brief introduction

character string Set, Disorder cannot be repeated , It's through HashTable Realized .

2. actual combat

sadd: Additive elements , The format is

SADD KEY_NAME VALUE1..VALUEN

smembers: Get all the elements in the collection , The format is

SMEMBERS key

sismember: Determines whether an element is in the set , The format is

SISMEMBER KEY VALUE

srem: Remove elements , The format is

SREM KEY MEMBER1..MEMBERN

scard: Get the number of elements in the collection , The format is

SCARD KEY_NAME

spop: Pop up elements , The format is

SPOP key [count]

smove: Move elements , The format is

SMOVE SOURCE DESTINATION MEMBER

3.4 Hash Hash type

brief introduction

Press Hash Method to store strings

actual combat

Set the value , The format is

HSET  KEY_NAME  FIELD  VALUE

hmset: Set multiple pairs of values at the same time , The format is

HMSET  KEY_NAME  FIELD1 VALUE1 ...FIELDN VALUEN

hgetall: Get the key Under all the values , The format is

HGETALL KEY_NAME

hget: Get a single key Value , The format is

HGET KEY_NAME FIELD_NAME 

hmget: Get multiple values at the same time , The format is

HMGET KEY_NAME FIELD1...FIELDN

hdel: Delete an item , The format is

HDEL KEY_NAME FIELD1.. FIELDN

3.5 zset Hash type

brief introduction

character string Set, Orderly and unrepeatable , according to Score Sort by .

actual combat

zadd: Additive elements , The format is

ZADD KEY_NAME SCORE1 VALUE1.. SCOREN VALUEN

score The sum can be many pairs ,score It can be an integer , It can also be a floating-point number , It can also be +inf It means positive infinity ,-inf Denotes negative infinity

zrange: Get the elements in the index interval , The format is

ZRANGE key start stop [WITHSCORES]

zrangebyscore: Get the elements in the fraction range , The format is

ZRANGEBYSCORE key min max [WITHSCORES]

zrem: Remove elements , The format is

ZREM key member [member ...]

zcard: Get the number of elements in the collection , The format is

ZCARD KEY_NAME