6.7 Fixing Hot Keys and Big Keys

Each fix for a problem key gives something up, such as freshness, memory in the application, or simple code. The previous lesson explained why hot keys and big keys defeat sharding and how to find them, using two examples: cfg:home, a configuration key that 100 application instances read 200,000 times per second in total, and feed:123, a list of 1 million entries. A hot key saturates the one node that owns it, and a big key blocks the main thread for every command that reads or frees all of it.

This lesson covers the fixes