Redis (IV) - string of common data types of redis

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brief introduction

String yes Redis One of the most basic data types , One key One by one value.
String Type is binary safe , signify Redis Of String Can contain any data , such as jpg Picture or serialized object
String The type is Redis Basic data types , One Redis Middle string value At most 512MB.

Common commands

1. Set a key value pair , If Redis The same key exists in , The original value will be overwritten .

 set  <key> <value>
  for example ： set k1 v1

2. Get the value of a key

 get <key>
  for example ：get k1

3. Delete specified key Value

del <key>
 for example ：del k1

4. Insert if it doesn't exist （not exists）,
   If it exists, it won't insert , This is a Redis Basic commands for distributed locks

  setnx <key> <value>
   for example ：127.0.0.1:6379> setnx username zhangsan
(integer) 1

5. Will be given <value> Append to the end of the original value

append <key> <value>

For example, the forward key k1 String is appended to 200.

7. <key> Get the length of the value

strlen <ken>

8. Increasing
   take key The number value stored in the 1, Can only operate on numbers , If it is empty , The new value added is 1.

incr <key>
incrby <key> <increment> 
 for example ：127.0.0.1:6379> incr age

command incrby <key> <increment> in <increment> It's the step length .

9. Decline
   take key The number stored in minus 1, Can only operate on numbers , The key for the operation must exist , And cannot be empty

decr <key>  
decrby  <key>  <decrement>

10. Set one or more... At the same time key-value Yes

mset <key1> <value1> <key2> <value2> ....

11. Get one or more at the same time value

gset <key1>  <key2> <key3> ....

12. Set one or more... At the same time key-value Yes , If and only if all given key It doesn't exist . The command is atomic .

msetnx <key1> <value1> <key2> <value2> ....

14. Get the range of values , Be similar to Java Medium substring, Front bag , Back bag

getrange <key> < The starting position > < End position >

15. use <value> overwrite <key> String value stored , from < The starting position > Start （ Index from 0 Start ）

setrange <key> < The starting position > <value>

16. While setting the key value , Set expiration time , Unit second

setex <key> < Expiration time > <value>

18. Trade in new for old , Set the new value and get the old value

getset <key> <value>

data structure

Redis（ 5、 ... and ）-Redis Of String The data structure of a string is a simple dynamic string

Reference resources

《Redis Design and implementation 》
Redis Basic types and their data structures
Simple dynamic string SDS