Five basic data structures of redis

Catalog

One 、String

1. brief introduction

2. Common commands

3. Examples of use

Two 、Hash

1. brief introduction

2. Common commands

3. Examples of use  

​ edit   3、 ... and 、List

1. brief introduction

2. Commonly used instructions

​ edit 3. Examples of use

Four 、Set

1. brief introduction

2. Common commands

3. Examples of use

5、 ... and 、ZSet

1. brief introduction

2. Common commands

3. Examples of use  

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One 、String

1. brief introduction

        String type , That is string type , yes Redis The simplest storage type in .

Its value Is string , However, depending on the format of the string , Can be divided into 3 class ：

string： Normal string

int： Integer types , Can do self increasing 、 Since the reduction of operating

float： Floating point type , Can do self increasing 、 Since the reduction of operating

Either format , The bottom layer is stored in the form of byte array , It's just that the coding method is different . The maximum space of string type cannot exceed 512m.

2. Common commands

SET： Add or modify an existing String Key value pairs of type 
GET： according to key obtain String Type of value
MSET： Batch add multiple String Key value pairs of type 
MGET： According to the multiple key Get multiple String Type of value
INCR： Let an integer key Self increasing 1
INCRBY: Let an integer key Increment and specify the step size , for example ：incrby num 2  Give Way num Value on the 2
INCRBYFLOAT： Increment a floating-point number and specify the step size 
SETNX： Add one String Key value pairs of type , The premise is this key non-existent , Otherwise, do not execute 
SETEX： Add one String Key value pairs of type , And specify the validity period 

3. Examples of use

 

Two 、Hash

1. brief introduction

Hash type , Also called hash , Its value It's an unordered Dictionary , Be similar to Java Medium HashMap structure . String Structure is to serialize an object into JSON Store after string , It is inconvenient to modify a field of an object ：

 Hash Structure can store each field in the object independently , You can do this for a single field CRUD：

2. Common commands

HSET key field value： Add or modify hash type key Of field Value 
HGET key field： Get one hash type key Of field Value 
HMSET： Batch add multiple hash type key Of field Value 
HMGET： Get more than one in batch hash type key Of field Value 
HGETALL： Get one hash Type of key All of them field and value
HKEYS： Get one hash Type of key All of them field
HVALS： Get one hash Type of key All of them value
HINCRBY: To make a hash type key The field value of is incremented and the step size is specified 
HSETNX： Add one hash Type of key Of field value , The premise is this field non-existent , Otherwise, do not execute 

3. Examples of use  

 

  3、 ... and 、List

1. brief introduction

Redis Medium List The type and Java Medium LinkedList similar , It can be regarded as a two-way linked list structure . It can support both forward retrieval and reverse retrieval .

Characteristics are also related to LinkedList similar ：

Orderly Elements can be repeated Insert and delete fast The query speed is average

Often used to store an ordered data , for example ： Friends circle the likes list , Comment list, etc .

2. Commonly used instructions

LPUSH key  element ... ： Insert one or more elements to the left of the list 
LPOP key： Remove and return the first element to the left of the list , No return nil
RPUSH key  element ... ： Insert one or more elements to the right of the list 
RPOP key： Remove and return the first element to the right of the list 
LRANGE key star end： Returns all elements within a range of subscripts 
BLPOP and BRPOP： And LPOP and RPOP similar , Just wait for the specified time when there is no element , Not directly back nil

3. Examples of use

 

Four 、Set

1. brief introduction

Redis Of Set Structure and Java Medium HashSet similar , It can be seen as a value by null Of HashMap. Because it is also a hash surface , Therefore, it has the ability to communicate with HashSet Similar features ： disorder Element is not repeatable Quick search Support intersection 、 Combine 、 Difference set and other functions

2. Common commands

SADD key member ... ： towards set Add one or more elements to 
SREM key member ... :  remove set The specified element in 
SCARD key：  return set The number of elements in 
SISMEMBER key member： Determine whether an element exists in set in 
SMEMBERS： obtain set All elements in 
SINTER key1 key2 ... ： seek key1 And key2 Intersection 
SDIFF key1 key2 ... ： seek key1 And key2 The difference between the set 
SUNION key1 key2 ..： seek key1 and key2 Union 

3. Examples of use

   5、 ... and 、ZSet

1. brief introduction

        Redis Of SortedSet It's a sortable set aggregate , And Java Medium TreeSet Some similar , But the underlying data structure is very different .SortedSet Each element in the has a score attribute , Can be based on score Attribute to sort elements , The underlying implementation is a jump table （SkipList） Add hash surface .

SortedSet It has the following characteristics ： Sortable Elements do not repeat Fast query speed

because SortedSet Sortable properties of , Often used to implement functions like leaderboards .

2. Common commands

ZADD key score member： Add one or more elements to sorted set , If it already exists, update its score value 
ZREM key member： Delete sorted set A specified element in 
ZSCORE key member :  obtain sorted set Of the specified element in score value 
ZRANK key member： obtain sorted set  The ranking of the specified elements in 
ZCARD key： obtain sorted set The number of elements in 
ZCOUNT key min max： Statistics score The number of all elements whose values are within a given range 
ZINCRBY key increment member： Give Way sorted set The specified element in is incremented , The step size is the specified increment value 
ZRANGE key min max： according to score After ordering , Get the elements within the specified ranking range 
ZRANGEBYSCORE key min max： according to score After ordering , Get specified score Elements in scope 

 Be careful ： All rankings are in ascending order by default , If you want to order in descending order, in the... Of the command Z Add later REV that will do 

3. Examples of use