Chapter 9. Reducing memory use

In this chapter, we’ll cover three important methods to help reduce your memory use in Redis. By reducing the amount of memory you use in Redis, you can reduce the time it takes to create or load a snapshot, rewrite or load an append-only file, reduce slave synchronization time,^[1] and store more data in Redis without additional hardware.

¹ Snapshots, append-only file rewriting, and slave synchronization are all discussed in chapter 4.

We’ll begin this chapter by discussing how the use of short data structures in Redis can result in a more efficient representation of the data. We’ll then discuss how to apply a concept called sharding to help make some larger structures small.^[2] Finally, we’ll talk about packing fixed-length data into STRINGs for even greater memory savings.

² Our use of sharding here is primarily driven to reduce memory use on a single server. In chapter 10, we’ll apply similar techniques to allow for increased read throughput, write throughput, and memory partitioning across multiple Redis servers.

9.1. Short structures

9.2. Sharded structures

9.3. Packing bits and bytes

9.4. Summary