Redis-Cheatsheet

Redis Cheatsheet

All the commands you need to know

redis-server /path/redis.conf # start redis with the related configuration file redis-cli # opens a redis prompt

Strings.

APPEND key value # append a value to a key BITCOUNT key [start end] # count set bits in a string SET key value # set value in key SETNX key value # set if not exist value in key SETRANGE key offset value # overwrite part of a string at key starting at the specified offset STRLEN key # get the length of the value stored in a key MSET key value [key value ...] # set multiple keys to multiple values MSETNX key value [key value ...] # set multiple keys to multiple values, only if none of the keys exist GET key # get value in key GETRANGE key value # get a substring value of a key and return its old value MGET key [key ...] # get the values of all the given keys INCR key # increment value in key INCRBY key increment # increment the integer value of a key by the given amount INCRBYFLOAT key increment # increment the float value of a key by the given amount DECR key # decrement the integer value of key by one DECRBY key decrement # decrement the integer value of a key by the given number DEL key # delete key

EXPIRE key 120 # key will be deleted in 120 seconds TTL key # returns the number of seconds until a key is deleted

Lists.

A list is a series of ordered values.

RPUSH key value [value ...] # put the new value at the end of the list RPUSHX key value # append a value to a list, only if the exists LPUSH key value [value ...] # put the new value at the start of the list LRANGE key start stop # give a subset of the list LINDEX key index # get an element from a list by its index LINSERT key BEFORE|AFTER pivot value # insert an element before or after another element in a list LLEN key # return the current length of the list LPOP key # remove the first element from the list and returns it LSET key index value # set the value of an element in a list by its index LTRIM key start stop # trim a list to the specified range RPOP key # remove the last element from the list and returns it RPOPLPUSH source destination # remove the last element in a list, prepend it to another list and return it BLPOP key [key ...] timeout # remove and get the first element in a list, or block until one is available BRPOP key [key ...] timeout # remove and get the last element in a list, or block until one is available

Sets.

A set is similar to a list, except it does not have a specific order and each element may only appear once.

SADD key member [member ...] # add the given value to the set SCARD key # get the number of members in a set SREM key member [member ...] # remove the given value from the set SISMEMBER myset value # test if the given value is in the set. SMEMBERS myset # return a list of all the members of this set SUNION key [key ...] # combine two or more sets and returns the list of all elements SINTER key [key ...] # intersect multiple sets SMOVE source destination member # move a member from one set to another SPOP key [count] # remove and return one or multiple random members from a set

Sorted Sets

A sorted set is similar to a regular set, but now each value has an associated score.

This score is used to sort the elements in the set.

ZADD key [NX|XX] [CH] [INCR] score member [score member ...] # add one or more members to a sorted set, or update its score if it already exists

ZCARD key # get the number of members in a sorted set ZCOUNT key min max # count the members in a sorted set with scores within the given values ZINCRBY key increment member # increment the score of a member in a sorted set ZRANGE key start stop [WITHSCORES] # returns a subset of the sorted set ZRANK key member # determine the index of a member in a sorted set ZREM key member [member ...] # remove one or more members from a sorted set ZREMRANGEBYRANK key start stop # remove all members in a sorted set within the given indexes ZREMRANGEBYSCORE key min max # remove all members in a sorted set, by index, with scores ordered from high to low ZSCORE key member # get the score associated with the given mmeber in a sorted set

ZRANGEBYSCORE key min max [WITHSCORES] [LIMIT offset count] # return a range of members in a sorted set, by score

Hashes

Hashes are maps between string fields and string values, so they are the perfect data type to represent objects.

HGET key field # get the value of a hash field HGETALL key # get all the fields and values in a hash HSET key field value # set the string value of a hash field HSETNX key field value # set the string value of a hash field, only if the field does not exists

HMSET key field value [field value ...] # set multiple fields at once

HINCRBY key field increment # increment value in hash by X HDEL key field [field ...] # delete one or more hash fields HEXISTS key field # determine if a hash field exists HKEYS key # get all the fields in a hash HLEN key # get all the fields in a hash HSTRLEN key field # get the length of the value of a hash field HVALS key # get all the values in a hash

HyperLogLog

HyperLogLog uses randomization in order to provide an approximation of the number of unique elements in a set using just a constant, and small, amount of memory

PFADD key element [element ...] # add the specified elements to the specified HyperLogLog PFCOUNT key [key ...] # return the approximated cardinality of the set(s) observed by the HyperLogLog at key's)

PFMERGE destkey sourcekey [sourcekey ...] # merge N HyperLogLogs into a single one

Publication & Subscription

PSUBSCRIBE pattern [pattern ...] # listen for messages published to channels matching the given patterns PUBSUB subcommand [argument [argument ...]] # inspect the state of the Pub/Sub subsystem PUBLISH channel message # post a message to a channel PUNSUBSCRIBE [pattern [pattern ...]] # stop listening for messages posted to channels matching the given patterns SUBSCRIBE channel [channel ...] # listen for messages published to the given channels UNSUBSCRIBE [channel [channel ...]] # stop listening for messages posted to the given channels

Other Commands

KEYS pattern # find all keys matching the given pattern