Preliminary understanding of redis

A preliminary understanding Redis

Redis It's completely open source , comply with BSD agreement , Is a high-performance key-value database .

Redis Characteristics

• Redis Support data persistence , The data in memory can be saved on disk , When you restart, you can load it again for use .
• Redis It's not just about supporting simple key-value Data of type , It also provides list,set,zset,hash Such as data structure storage .
• Redis Support data backup , namely master-slave Mode data backup .
• atom – Redis All operations of are atomic , It means either successful execution or failure and no execution at all . Individual operations are atomic . Multiple operations also support transactions , Atomicity , adopt MULTI and EXEC Package the instructions .

 function Reids after , Open another one cmd window , Switch to redis Operating under the directory 
 Enter the command ：redis-cli.exe -h 127.0.0.1 -p 6379
 Set key value pairs ：set myKey abc
 Take out the key value pair ：get myKey

Redis To configure

Redis The configuration file is located in Redis Installation directory , The file named redis.conf(Windows be known as redis.windows.conf).

 View the configuration file , The grammar is ：config get +  Profile name  // View all profiles CONFIG GET *
 It can be modified by  redis.conf  Document or use  config set  Command to modify the configuration .
 Example ：
redis 127.0.0.1:6379> CONFIG SET loglevel "notice"
OK
redis 127.0.0.1:6379> CONFIG GET loglevel
1) "loglevel"
2) "notice"

Redis Please check the configuration details Novice tutorial Redis To configure

Reids data type

Redis Five data types are supported ：string（ character string ）,hash（ Hash ）,list（ list ）,set（ aggregate ） And zset(sorted set： Ordered set ).

String type ：

• string The type is Redis Basic data types , One key Corresponding to one value.

• string Type is binary safe . intend redis Of string Can contain any data . such as jpg Picture or serialized object .

• string The maximum value of type can store 512MB.

Hash（ Hash ） type ：

• Redis hash It's a key value (key=>value) The collection .

• Redis hash It's a string Type of field and value Mapping table ,hash Ideal for storing objects .

redis 127.0.0.1:6379> DEL runoob
redis 127.0.0.1:6379> HMSET runoob field1 "Hello" field2 "World"
"OK"
redis 127.0.0.1:6379> HGET runoob field1
"Hello"
redis 127.0.0.1:6379> HGET runoob field2
"World"
 In the example, we use  Redis HMSET, HGET  command ,HMSET  Set up two  field=>value  Yes , HGET  Get corresponding  field  Corresponding  value.
 Every  hash  Can be stored  232 -1  Key value pair （40 More than ）.

List（ list ） type ：

Redis List is a simple list of strings , Sort by insertion order . You can add an element to the head of the list （ On the left ） Or tail （ On the right ）.

redis 127.0.0.1:6379> DEL runoob
redis 127.0.0.1:6379> lpush runoob redis
(integer) 1
redis 127.0.0.1:6379> lpush runoob mongodb
(integer) 2
redis 127.0.0.1:6379> lpush runoob rabbitmq
(integer) 3
redis 127.0.0.1:6379> lrange runoob 0 10
1) "rabbitmq"
2) "mongodb"
3) "redis"
redis 127.0.0.1:6379>

set（ aggregate ） type ：

• Redis Of Set yes string Unordered collection of type .

• Collections are implemented through hash tables , So add the , Delete , The complexity of searching is O(1).

• sadd Command to add a string Element to key Corresponding set Collection , Successfully returns 1, If the element has already returned in the collection 0.

redis 127.0.0.1:6379> DEL runoob
redis 127.0.0.1:6379> sadd runoob redis
(integer) 1
redis 127.0.0.1:6379> sadd runoob mongodb
(integer) 1
redis 127.0.0.1:6379> sadd runoob rabbitmq
(integer) 1
redis 127.0.0.1:6379> sadd runoob rabbitmq //rabbitmq Has been added , Elements added again will be ignored 
(integer) 0
redis 127.0.0.1:6379> smembers runoob

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

zset(sorted set： Ordered set ) type ：

• Redis zset and set The same is true. string Collection of type elements , And duplicate members are not allowed .

• The difference is that each element is associated with a double Score of type .redis It's the scores that sort the members of a collection from small to large .

• zset Members of are unique , But fractions (score) But it can be repeated .

redis 127.0.0.1:6379> DEL runoob
redis 127.0.0.1:6379> zadd runoob 0 redis
(integer) 1
redis 127.0.0.1:6379> zadd runoob 0 mongodb
(integer) 1
redis 127.0.0.1:6379> zadd runoob 0 rabbitmq
(integer) 1
redis 127.0.0.1:6379> zadd runoob 0 rabbitmq
(integer) 0
redis 127.0.0.1:6379> ZRANGEBYSCORE runoob 0 1000
1) "mongodb"
2) "rabbitmq"
3) "redis"