Caching - A Primer

1. Caching and Django A Primer @ashchristopher
2. What is a Cache?
3. Temporary storage of non-complex data
4. Provides very fast lookups
5. Django supports simple caching
6. Django includes support for a number of cache backends out-of-the-box
7. Memcache cluster of Memcache servers Database cache uses database table for cache Filesystem cache file on the local filesystem Local memory cache only good for local development
8. Easy to make your own cache backend
9. Extend core.cache.backends.base.BaseCache
10. Simple caching follows the same pattern
11. 1. Check the cache for data and if found, return it 2. If data is not in cache - get data from the database, put data in cache then return the data 3. Invalidate cache on data change.
12. Your system works even if your cache is offline
13. Some cool projects/apps to help you with it
14. Django Middleware (per-site and per-view)
15. Cache Machine
16. Johnny-Cache
18. Low-level Caching (doing it by hand)
19. Caching is simple...
20. ... except when it isn’t!
21. Cache invalidation is hard
22. Cache invalidation is especially hard at scale
23. What happens when an expensive operation falls out of cache?
24. Thundering Herd
25. Fundamental flaw?
26. I think so!
27. Caching doesn’t mean what it used to mean
28. What you want is probably not caching
29. Denormalized Data
30. Actively set new data instead of letting things fall out of cache
31. Nothing falls out of cache
32. Set your data via asynchronous processes
34. No Silver Bullet
35. Optimizing read speed by adding redundant data
36. Persistent storage
37. NoSQL
38. There is a problem with denormalized data at scale
39. Denormalized data becomes a requirement
40. What problem?
41. Embrace denormalized data
42. @ashchristopher ash.christopher@gmail.com