Redis Storage Fabric

Redis is now a popular cache database, and it is generally found that it can store strings (string), hash tables (hashes), lists, collections (set), ordered collections (sorted set), and so on. Redis is a Key-value store, and value can contain many of the structures listed above, but key is a string. This means that key is a string type and value is one of the above types.

Since the storage instructions for each of these data structures are not the same in Redis, it seems that a single redis must differentiate the structure of the objects to be stored and then choose the appropriate instructions. But it's really bad to use it, and if you want to deposit multiple forms of value at once, I'm going to implement a variety of storage methods.

To facilitate the development and use of Redis introduced objects, namely object storage. Each of the above data structures is an object, so you only need to implement the object's storage in your project.

Each object in Redis has a redisobject structure in which the three properties associated with saving data are the type of the data being stored, the encoding attribute of the value encoding, and the pointer ptr property:

typedef struct redisobject{
//type
unsigned type:4;

Coding
unsigned encoding:4;

Pointer to the underlying implementation data structure
void *ptr

//virtual memory and other information etc....
} RobJ;

Type Constants	the name of the object	Type value
Redis_string	String Object	String
Redis_list	List objects	List
Redis_hash	Hash object	Hash
Redis_set	Collection Object	Set
Redis_zset	Ordered collection objects	Zset

Gets the type encoding directive that stores the value:
TYPE Key

For example, I'm storing a string value in Redis:

[root@iz8vb8r420ejxfron03cj7z ~]# redis-cli
127.0.0.1:6379> set msg "Rhett"  
OK
127.0.0.1:6379> get Msg
"Rhett"
127.0.0.1:6379> type msg
string

Encoding Constants	the name of the object	Type value
Redis_encoding_int	Integer	Int
Redis_encoding_embstr	Embstr coded simple dynamic string (SDS)	List
Redis_encoding_raw	Simple dynamic string	Raw
Redis_encoding_ht	Dictionary	Hashtable
Redis_encoding_linkedlist	Double-ended linked list	LinkedList
Redis_encoding_ziplist	Compression list	Ziplist
Redis_encoding_intset	Integer collection	Intset
Redis_encoding_skiplist	Jumping Tables and dictionaries	Skiplist

Examples in Redis:

[root@iz8vb8r420ejxfron03cj7z ~]# redis-cli
127.0.0.1:6379> set msg "Rhett"  
OK
127.0.0.1:6379> Object encoding msg
"EMBSTR"

Reference book: Design and implementation of Redis