1 REDIS SERVER An Introduction to REDIS SERVER, an advanced key value database By: Ali MasudianPour 

2 What REDIS is ● Redis is an open source, BSD licensed, advanced key-value store. It is often referred to as a data structure server since keys can contain strings, hashes, lists, sets and sorted sets. ● REDIS – It stands for REmote DIctionary Server 

3 Features ● not a plain key-value store, a data structures server ● supporting different kind of values ● Free and open source ● Easy to user ● Easy to learn 

4 Supported Data Types ● Binary-safe strings. ● Lists of binary-safe strings. ● Sets of binary-safe strings, that are collection of unique unsorted elements. ● Sorted sets, similar to Sets but where every element is associated to a floating number score. The elements are taken sorted by score. 

5 KEYS - VALUES ● In REDIS, Keys are binary safe – This means that you can use any binary sequence as key ● From String like 'foo' to the content of a JPEG file – REDIS keys accept empty ● In REDIS, Values – Can not be bigger than 512MB – 

6 SET ● To set a value to a key we use SET statement – SET key value ● Example: – SET foo bar – In above example we told redis to set bar value to foo key ● To set string value we use double quotations – SET keyname “The string content of value” 

7 GET ● To get a value from redis we use GET statement – GET keyname ● Example – GET foo // it will return bar – In above example we told redis to get foo key value. 

8 INCR, INCRBY ● Automatic increment by REDIS – To use automatic increment of redis we use INCR ● Example: – Set counter 1 incr counter // Output wil be 2 ● We can also use INCRBY – Set counter 1 – Incr counter – // Output wil be 2 – Incrby counter 10 – //outpur will be 12 

9 DECR, DECRBY ● In opposite of INCR and INCRBY redis contains DESC and DESCBY – Just like DECR and DECRBY – Set counter 10 decr counter // Output wil be 9 decrby counter 5 //output will be 4 

10 EXPIRE and TTL ● In REDIS we can set keys to expire in a given and specific amount of time. – To do that we use EXPIRE command – Example ● Set foo bar ● Expire foo 50 – To find out how many time a key have we use TTL command ● For instance after 10 second of declaring foo key if we use TTL command the output will be something like below: – Ttl foo //40 

11 LISTS ● To create a list use LPUSH or RPUSH. If a list already exists, LPUSH will add the given value to the beginning of the list and RPUSH will add it to the end. ● Redis lists contain the following commands – SORT – RPUSH – LPUSH – LLEN – LTRIM – LRANGE – LPOP – RPOP – BLPOP – BRPOP – And ... 

12 LISTS redis 127.0.0.1:6379> lpush ages 10 (integer) 1 redis 127.0.0.1:6379> lpush ages 13 (integer) 2 redis 127.0.0.1:6379> lpush ages 12 (integer) 3 redis 127.0.0.1:6379> lpush ages 6 (integer) 4 redis 127.0.0.1:6379> LRANGE ages 0 3 1) "6" 2) "12" 3) "13" 4) "10" redis 127.0.0.1:6379> sort ages 1) "6" 2) "10" 3) "12" 4) "13" ----------------------------- redis 127.0.0.1:6379> lpop ages "6" redis 127.0.0.1:6379> rpop ages "10" redis 127.0.0.1:6379> LRANGE ages 0 10 1) "12" 2) "13" redis 127.0.0.1:6379> 

13 SETS ● Sets are similar to lists but does not support duplication ● Example: – Add to sets ● redis 127.0.0.1:6379> SADD names "Michael" (integer) 1 redis 127.0.0.1:6379> SADD names "JOHN" (integer) 1 redis 127.0.0.1:6379> SMEMBERS names 1) "JOHN" 2) "Michael" redis 127.0.0.1:6379> ● SADD adds to set and SMEMMEBRS show the member of set 

14 Lists ● Now, if you try to add another set member with JOHN value it will do nothing, because sets do not support duplication. ● Other useful commands for set – SADD, SREM, SPOP, SMOVE, SCARD, SISMEMBER, SINTER, SINTERSTORE, SUNION, SUNIONSTORE, SDIFF, SDIFFSTORE, SMEMBERS, SRANDMEMBER. 

15 HASHES ● Using a hash, you can assign values to fields in each key. ● Common Commands in hashes are: – HSET, HGET, HSETNX, HMSET, HMGET, HINCRBY, HEXISTS, HDEL, HLEN, HKEYS, HVALS, HGETALL 

16 Example of HASHES redis 127.0.0.1:6379> hset student name "Ali" (integer) 1 redis 127.0.0.1:6379> hset student lastName "MasudianPour" (integer) 1 redis 127.0.0.1:6379> hset student number 101222 (integer) 1 redis 127.0.0.1:6379> hget student name "Ali" redis 127.0.0.1:6379> hget student lastName "MasudianPour" redis 127.0.0.1:6379> HGETALL student 1) "name" 2) "Ali" 3) "lastName" 4) "MasudianPour" 5) "number" 6) "101222" 

17 End ● This document is provided to be a little familiar with REDIS. I hope it help you to start working with REDIS.