1. Redis And Python PyCon India, 2011 (Work in Progress) Sunil Arora

2. Raising Hands... How many of you have used Redis before ? How many of you have got a laptop here ?

3. Who Sunil Arora / @_sunil_ Work for ShopSocially (http://shopsocially.com)http://shopsocially.com Interests: Backend, Frontend, scaling, internet technologies in general, startups... all kind of shit

4. Who Sunil Arora / @_sunil_ Work for ShopSocially (http://shopsocially.com)http://shopsocially.com Interests: Backend, Frontend, scaling, internet technologies in general, startups...

5. Today's talk What is Redis How it works and what you can do with it Real life use-cases

6. What is Redis ? Its between lot of stuff, so difficult to categorize it precisely

7. What is Redis ? I see Redis definitely more as a flexible tool that as a solution specialized to solve a specific problem: his mixed soul of cache, store, and messaging server shows this very well -Salvatore Sanfilippo Picture by herzogbr http://www.flickr.com/photos/herzogbr/2274372747/sizes/z/in/photostream/

8. Brief History of Redis Released in March 2009 by Salvator Sanfilippo (@antirez) Open source, BSD licensed VMWare sponsored its development in March, 2010

9. A few fundamentals Written in C (25K LOC) Uses memory as main storage Single Threaded Uses disk for persistence Screamingly fast performance 50K read/write operations per seconds 200K read/write ops per second on a regular EC2 instance

10. Installation $ git clone http://github.com/antirez/redishttp://github.com/antirez/redis $ cd redis $ make $./src/redis-server..........

11. redis-py The most popular python client library Andy McCurdy (sedrik@gmail.com)sedrik@gmail.com Github: http://github.com/andymccurdy/redis-py easy_install redis OR pip install redis Optional: easy_install hiredis or pip install hiredis

12. Lets get started... $ cd redis $./src/redis-server......... >>> from redis import Redis >>> redis_client = Redis() >>> redis_client.keys() >>> help(redis_client)

13. Redis Keys Not binary safe. Should not contain space or newline character A few rules about keys: Too long keys are not a good idea Too short keys is also not a good idea “object-type:id:field” can be a nice idea, i.e. “user:1001:name”

14. Operations on Keys KEYS EXISTS DEL EXPIRE OBJECT PERSIST RANDOMKEY RENAME TYPE TTL EXPIREAT MOVE

15. Lets play with keys >>>redis_client.keys() >>>redis_client.exists('key') >>>redis_client.delete('key') >>>redis_client.type('key') >>>......

16. Data Structures Strings Lists Sets Sorted Sets Hashes

17. Strings SET GET MSET MGET SETEX INCR INCRBY DECR DECRBY

18. Strings – with redis client >>> redis_client.set('key', 'value') >>> redis_client.get('key') >>> redis_client.delete('key')

19. Fetch multiple keys at once mget/mset redis_client.mset({'key1': 'val1', 'key2': 'val2'}) redis_client.mget('key1', 'key2',......)

20. Expiration Set a value with expire >>>redis_client.setex('key', 'value', 2) #key to expire in 2 secs >>>redis_client.expire('key', 2) >>>redis_client.get('key') >>>None

21. Uses To store transient states in your web application

22. Uses Who is online?

23. Uses Redis as LRU cache (http://antirez.com/post/redis- as-LRU-cache.html)

24. Atomic Increments >>>help(redis_client.incr) >>>help(redis_client.decr) >>> >>> redis_client.incr('counter', 1) >>>1 >>> redis_client.incr('counter') >>>2 >>> redis_client.incr('counter') >>>3

25. Uses High Speed counters (views/clicks/votes/likes..)

26. Uses API Rate Limiting

27. Uses Generating unique IDs

28. Lists Ordered list of binarysafe strings Doubly linked list Memory footprint optimized for smaller list O(1) insertion/deletion at both ends

29. Lists - operations LPUSH RPUSH LSET LRANGE LPOP BLPOP BRPOP BRPOPLPUSH LINSERT RPOP RPOPLPUSH LPUSHX RPUSHX

30. Uses Web apps are full of lists :)

31. Uses Capped List

32. Uses Normal Queue Real time message Queue

33. Uses Social Activity Streams

34. Sets An unordered collection of distinct byte strings Nothing different from the data type in python

35. Sets - Operations SADD SCARD SDIFF SDIFFSTORE SINTER SINTERSTORE SISMEMBER SMEMBERS SMOVE SPOP SRANDMEMBER SREM SUNION SUNIONSTORE

36. Uses Picking random items from a set using SRANDMEMBER

37. Uses Primitive to construct filtering mechanism on items

38. Which of my friend's are online right now? Uses

39. Sorted Sets ZADD ZCARD ZCOUNT ZINCRBY ZINTERSTORE ZRANGE ZRANGEBYSCORE ZRANK ZREM ZREMRANGEBYRA NK ZREMRANGEBYSC ORE ZREVRANGE ZREVRANGEBYSCO RE ZSCORE ZUNIONSTORE

40. SORT SORT KEY SORT key BY pattern (e.g. object-type:*:age) SORT key LIMIT 0 10 SORT key GET user:*:username SORT key BY pattern STORE dstkey

41. Uses Generating sorted transient views

42. Publish/Subscribe A simple and efficient implementation of publish/subscribe messaging paradigm Client can subscribe/psubscribe to receive messages on channels (key patterns)

43. Publish/Subscribe PSUBSCRIBE PUBLISH PUNSUBSCRIBE SUBSCRIBE UNSUBSCRIBE

44. Uses Many to Many message passing

45. Uses Web Chat

46. Questions