Redis is an in-memory data structure store, used as a database, cache, and message broker. It supports string, list, set, sorted set and hash data types and operates on keys and values. Some common uses of Redis include caching, queues, leaderboards and real-time analytics. It has client libraries for many languages and is fast due to operating in memory.

1. Redis 맛보기
jhoh@encoredtech.com

2. Redis
● REmote DIctionary Server
● In-memory, but can be persisted
● NoSQL Key-value store
● Written in ANSI C
● No threading, just one process

3. The Most Popular Key-Value Store

4. Why Redis?
● Fast
● Easy to learn
● Various data types
● Solve a specific set of problems
○ Good: Caching, Statistical data, Recoverable state,
Worker Queue
○ Bad: 100% consistent dataset required, Data is
larger than memory

5. Running & Connecting
● redis-server
● redis-cli
● http://try.redis.io/

6. Redis Protocol
redis[“key”] = “value”

7. Key
● Redis key is Binary safe, this means that you can use
any binary sequence as a key:
○ string
○ content of a JPEG file
○ also, empty string

8. Rules about Keys
● Too long keys are not a good idea
○ memory-wise, costly key-comparisons
● Too short keys are often not a good idea
○ more readable
○ id:10:pass => id:10:password
● Try to stick with a schema
○ “object-type:id:field” => “comment:1234:reply.to”

9. Value types
● String
● List of strings
● Sets of strings
● Sorted sets of strings
● Hashes where keys and values are strings

10. String
● The simplest Redis type
● A value can’t be bigger than 512 MB
● SET
● GET
● INCR/INCRBY, DECR/DECRBY
● GETSET

11. 127.0.0.1:6379> set mykey 100
OK
127.0.0.1:6379> get mykey
"100"
127.0.0.1:6379> incr mykey
(integer) 101
127.0.0.1:6379> incrby mykey 5
(integer) 106
127.0.0.1:6379> decr mykey
(integer) 105
127.0.0.1:6379> decrby mykey 2
(integer) 103
127.0.0.1:6379> getset mykey 1
"103"
127.0.0.1:6379> get mykey
"1"
Example Of String

12. List
● Implemented via Linked Lists
● LPUSH
○ add a new element into a list at the head
● RPUSH
○ add a new element into a list at the tail
● LRANGE

13. 127.0.0.1:6379> incr next.news.id
(integer) 1
127.0.0.1:6379> set news:1:title "Redis is simple"
OK
127.0.0.1:6379> set news:1:url "http://code.google.com/redis"
OK
127.0.0.1:6379> lpush submitted.news 1
(integer) 1
Push IDs instead of the actual data
reddit.com example:

14. Sets
● Unordered collections of unique strings
● SADD
● SMEMBERS
● SISMEMBER
● SINTER
○ the intersection between different sets

15. Sorted Sets
● Collections of unique strings with associated
score
● ZADD
○ O(log(N))
● ZRANGE/ZREVRANGE
● ZRANGEBYSCORE

16. ZADD
Add a few selected hackers with their year of birth as score
127.0.0.1:6379> zadd hackers 1940 "Alan Kay"
(integer) 1
127.0.0.1:6379> zadd hackers 1953 "Richard Stallman"
(integer) 1
127.0.0.1:6379> zadd hackers 1965 "Yukihiro Matsumoto"
(integer) 1
127.0.0.1:6379> zadd hackers 1916 "Claude Shannon"
(integer) 1
127.0.0.1:6379> zadd hackers 1969 "Linus Torvalds"
(integer) 1
127.0.0.1:6379> zadd hackers 1912 "Alan Turing"
(integer) 1

17. ZRANGE/ZREVRANGE
Ask for sorted hackers
127.0.0.1:6379> zrange hackers 0 -1
1) "Alan Turing"
2) "Claude Shannon"
3) "Alan Kay"
4) "Richard Stallman"
5) "Yukihiro Matsumoto"
6) "Linus Torvalds"
127.0.0.1:6379> zrevrange hackers 0 -1
1) "Linus Torvalds"
2) "Yukihiro Matsumoto"
3) "Richard Stallman"
4) "Alan Kay"
5) "Claude Shannon"
6) "Alan Turing"

18. Sorted Set by different ordering
● Use SORT command
○ Server will waste CPU
● Make another sorted set
○ An alternative for having multiple orders is to add
every element in multiple sorted sets at the same
time.

19. Updating the scores
● Just calling again ZADD

20. Hashes
● HSET
● HGET
● HGETALL
● HKEYS

21. 127.0.0.1:6379> hset users:1 username poby
(integer) 1
127.0.0.1:6379> hget users:1 username
"poby"
127.0.0.1:6379> hmset users:1 age 10 bestfriend pororo
OK
127.0.0.1:6379> hgetall users:1
1) "username"
2) "poby"
3) "age"
4) "10"
5) "bestfriend"
6) "pororo"
127.0.0.1:6379> hkeys users:1
1) "username"
2) "age"
3) "bestfriend"
127.0.0.1:6379> hdel users:1 age
(integer) 1
Example Of Hash

22. Redis Clients
http://redis.io/clients

23. Demo: realtime-info
AWS ElastiCache
realtime-info
EDM1
EDM1
EDM1
EDM1
EDM1
EDM1
API Server
Log Server

24. Demo: Realtime-Info (1)
SET realtime-info by Poby

25. Demo: Realtime-Info (2)
MGET realtime-info by API

26. 참고 자료
● Redis - Wikipedia
● Redis - Fast and Furious
● 15 minutes introduction to Redis data types
● The Little Redis Book
● redis.io

27. 끝