Dragonfly's New Sorted Set Implementation

Redis, a popular in-memory data store, offers sorted sets as a unique and powerful data type. However, the original implementation of sorted sets had some inefficiencies that prompted developers to rebuild them from scratch using a B+ tree structure. This new implementation significantly reduces memory usage and improves performance compared to Redis's skiplist-based approach. The benchmark results show that Dragonfly, which uses this new sorted set implementation, can sustain higher throughput and efficiently scales vertically when more CPUs are available. Additionally, the B+ tree-based sorted sets exhibit up to 40% memory reduction compared to Redis's original implementation.