Redis

index

Learning :

Redis for Beginners - Net Ninja Redis Crash Course - Web Dev Simplified

Redis is like Map in JS, KEY = VALUE and VALUE is usually/default stored as string

Terminal Commands :

• Open WSL : wsl
• Start Redis server : redis-server
• Open Redis server : redis-cli
• Quit CLI : quit
• SET pair : SET KEY VALUE
• GET VALUE : GET KEY
• DELETE VALUE : DEL KEY
• CHECK IF KEY EXIST : EXISTS KEY
• LIST ALL KEYS : KEYS *
• DELETE WHOLE REDIS DATA : flushall

Expiration (time limit) of a key :

• ttl KEY === -1 then key exist but don’t have expiration time
• ttl KEY === -2 then key don’t exist
• ttl KEY === positive integer is seconds left.
• to set expiration time of stored KEY ⇒ expire KEY 10 here 10 is 10sec
• to set expiration time of NEW KEY ⇒ setex KEY 10 VALUE

List (doubly queue) :

• lpush KEY VALUE ⇒ make an array of name KEY(if not exist) and push VALUE at the START of array.
• rpush KEY VALUE ⇒ make an array of name KEY(if not exist) and push VALUE at the END of array.
• lrange KEY 0 -1 ⇒ list all values in array.
• LPOP KEY ⇒ pops out first element.
• RPOP KEY ⇒ pops out last element.

Sets (like maths sets allow only unique values) :

• SADD KEY VALUE ⇒ creates set KEY if not exist and then add VALUE
• SMEMBERS KEY ⇒ list all values in set KEY.
• SREM KEY VALUE ⇒ removes VALUE from KEY set.

Hashes (key value pairs inside a key value pair (but hashes can’t be nested))

• HSET KEY KEY VALUE === KEY = { KEY: VALUE }
• Example : HSET person name kyle === person = { name: kyle }
• HGET person name outputs kyle.
• HSET person age 26
• HGETALL person outputs :

"name"
"kyle"
"age"
"26"

• HDEL person age ⇒ deletes age from person.
• HEXIST person age ⇒ (checks if age exist) outputs 0 as age is deleted.