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Introduction to some top Redis use cases

  1. An Introduction to Top Redis Use Cases by Dr. Josiah Carlson @dr_josiah
  2. Agenda ● Who am I? ● What is Redis? ● Top use cases ● Questions
  3. Who am I? ● A guy who does a lot of stuff with Redis and Python ○ Book: ■ Redis in Action ■ Read for free ○ Libraries: ■ rom, RPQueue, lua_call, ... ○ Mailing list:!forum/redis-db ○ Blog: ○ Twitter: @dr_josiah
  4. What is Redis? ● In-memory non-relational key -> data structure server ○ integers, floats, strings, bitmaps, hyperloglogs, lists, sets, hashes, sorted sets(, geoindex) ○ Plus pubsub, key change notifications, ... ● Optional on-disk persistence ● Optional master/slave replication ○ Optional sentinel for high-availability/failover ● Optional separate clustering mode as of April 2015 ● Server-side Lua scripts (like stored procedures, only easier) ● Third party client-sharding via clients or Twemproxy/Nutcracker
  5. Use-case 1: Distributed locking ● 10-100x faster than Zookeeper by default ○ can be tuned for the same reliability ● Multiple locks at the same time ○ job input/output coordination ■ MySQL DDL/truncate operations - locking outside can save your bacon ○ locks that “never” time out ○ locks that time out, or require refreshing ○ counting semaphores for multiple lock holders
  6. Use-case 2: Analytics ● Stop counting after the fact ○ Handle 100-200k events/second without pipelining/batching ○ Handle 1M+ events/second with pipelining/batching ■ Send one batched call at the end of the request ● Use a Lua script for hierarchical counters ● As simple as a counter, or with a little work min/max/avg/stddev ● Minor modifications get you rate limiting ○ Login, API, bandwidth utilization, … ○ With locking (and counting semaphores), can limit outgoing API usage ○ Pick your semantic: counters, sliding window, leaky bucket, or something else
  7. Use-case 3: Web cookies ● No more: ○ encrypting/signing your cookies badly (still need to make them https-only) ○ running into 4k cookie limits ○ slow mobile requests due to overweight cookies ● Easily structured cookie data storage ○ Shopping carts ○ Last X pages visited per user ■ Real-time analytics/trend analysis over recent pages, where to go, what to buy, etc. (people who viewed this item bought item X some Y% of the time) ○ A listing of recent logins per user, with cookie deletion
  8. Use-case 4: Queues/message passing ● Libraries in most languages ○ Use an off-the-shelf library, or write one that fits your required semantics (0/1 or 1+) ● Prioritization, delayed, cron-scheduled, every X seconds, etc. ● Blocking queues with listeners listening on multiple queues ● Broadcasting with pubsub ● If you like Redis, but want a queue ○ Salvatore has written Disque, a 1+ queue system
  9. Use-case 5: Anything you’re using Memcached for ● Memcached does strings and ints ● Redis does ○ integers, floats, strings, bitmaps, hyperloglogs, lists, sets, hashes, sorted sets(, geoindex) ○ pubsub (generally, and keyspace changes) ○ optimistic locking and basic transactions with WATCH/MULTI/EXEC ○ Lua scripting ■ … a literally uncountable number of things that Memcached can’t do
  10. ...and many more ● DB row caching ● Web page caching ● Autocomplete ● Dynamically updated toplists for games ● Generalized voting/ranking (Reddit, Hacker News, etc.) ● Unique visitor counts on hourly, daily, weekly, and/or monthly basis ● Custom search engines/ad targeting ● Rate-limited geo notifications ● As a general data store (various libraries, some with pseudo-relational layer)
  11. Questions?
  12. Thank you! @dr_josiah