Redis

• no-sql database, doesn’t have tables or documents

• data is stored in key, value pairs

• runs inside memory and much more volatile

• used mainly for caching, on top of other database

• stored as string by default

SET key value
GET key   # GET only works for string
DEL key
EXISTS key  # return 1 or 0
KEYS *  # get all keys
FLUSHALL  # clear all
TTL key  # time to live, -1 for forever, -2 for gone
EXPIRE key  # set time for expire
SETEX key time value  # set key with expire time in seconds

• also support for handling arrays in list form and hashes for json

• every key in a set has to be unique

LPUSH key value  # add item at the start/left of the array
LRANGE key start end  # 0 -1 to print all
RPUSH key value  # add item at the end/right of the array
LPOP key  # remove item at the start/left
RPOP key  # remove item at the end/right

SADD key value  # add item to a set
SMEMBERS key  # list all items in a set
SREM key value  # remove a key from a set

HSET key field value  # add a value to a field of a key
HGET key field  # get a value of a field from a key
HGETALL key  # get all fields and values from a hash, prints field first
HDEL key field  # delete a field from a key
HEXISTS key field  # return 1 or 0