Redis

Basics

Strings

• SET foo 100 to set a key value pair
  • You can set values as SET server:name someserver and get it with GET server:name
• GET foo will return 100
• INCR foo -> to increment a value
• EXISTS foo -> Determines if the key exits
  • It will return 1 if the value exists otherwise will return 0
• DEL foo -> to delete a value
• FLUSHALL -> to erease everything
• EXPIRE foo 50 -> to give an expiration time to our values
• TTL foo -> to see how long this value has
• SETEX foo 40 "Hello world" to set the value and the expiration at the same time
• PERSIST foo -> to cancel the expiration time.
• MSET key1 "Hello1" key2 "World" -> to set multiple values at the same time
• APEND key1 "World" -> Append
• RENAME key1 greeting -> to change the key name

Lists

• LPUSH people "Giovanni" -> to push a name to the people's list
• LRANGE people 0 -1 -> to output all the values in the list (0 to -1 indecates all the range) Lists are 0 base
• RPUSH people "Jenny" to push a value to the end of the list.
• LLEN people -> Gives the lists length
• LPOP people -> Eliminate the first element of the list
• RPOP people -> Eliminate the last element of the list
• LINSERT people BEFORE "Jenny" "May" -> Will insert before a certain element.

SETS

Is an unorder collection of strings

• SADD cars "FORD" -> to add to the set
• SISNUMBER cars "FORD" -> will determinate if it exists.
  • If return 1 the value exists in the set otherwise returns 0
• SMEMBERS cars -> return all members of the set.
• SCARD cars -> Gives how many elements
• SMOVE cars mycars "Ford" to move an element to another set.
• SREM cars "Ford -> is to remove an element of the set.

Source Sets

The difference between source sets and sets is that every memeber of the sorce set is associated with a score

• ZADD users 1980 "Giovanni" -> To Add an element to the source set 1980 will be its score
• ZRANK users "Giovani" -> To know it which position is that score
• ZRANGE users 0 -1 -> Print all the source set
• ZINCRBY user 1 "Giovanni" -> Will return 1981 to the score

Hashes

• HSET user:gp1234 name "Giovanni"
• HSET user:gp1234 email "giovanni@gmail.com"
• HGET user:gp1234 name
• HGETALL user:gp1234 -> To return all the values
• HMSET user:gp1234 name "Giovanni" email "giovanni@gmail.com" age: "24" -> To set multiple values at the same time.
• HKEYS user:gp1234 -> to get all the keys
• HVALS user:gp1234 -> to get just the values
• HINCRBY user:gp1234 age 1 -> to increment a value
• HDEL user:gp1234 age -> to delete a key-value pair
• HHLEN user:gp1234 -> to get the number of key-value pairs

Data Persistence

• SAVE -> will create a snapshot of our values
• SAVE 60 1000 -> every 60 seconds save if a 1000 of items have change
• You can set appendonly yes in the redis configuration file and it will log everything

Links

Great free crash course