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3379cbcaa4
## Problem This follows a PR that insists all input keys are representable in 16 bytes: - https://github.com/neondatabase/neon/pull/8648 & a PR that prevents postgres from sending us keys that use the high bits of field2: - https://github.com/neondatabase/neon/pull/8657 Motivation for this change: 1. Ingest is bottlenecked on CPU 2. InMemoryLayer can create huge (~1M value) BTreeMap<Key,_> for its index. 3. Maps over i128 are much faster than maps over an arbitrary 18 byte struct. It may still be worthwhile to make the index two-tier to optimize for the case where only the last 4 bytes (blkno) of the key vary frequently, but simply using the i128 representation of keys has a big impact for very little effort. Related: #8452 ## Summary of changes - Introduce `CompactKey` type which contains an i128 - Use this instead of Key in InMemoryLayer's index, converting back and forth as needed. ## Performance All the small-value `bench_ingest` cases show improved throughput. The one that exercises this index most directly shows a 35% throughput increase: ``` ingest-small-values/ingest 128MB/100b seq, no delta time: [374.29 ms 378.56 ms 383.38 ms] thrpt: [333.88 MiB/s 338.13 MiB/s 341.98 MiB/s] change: time: [-26.993% -26.117% -25.111%] (p = 0.00 < 0.05) thrpt: [+33.531% +35.349% +36.974%] Performance has improved. ```
Pageserver Benchmarks
How to run
To run all benchmarks:
cargo bench
To run a specific file:
cargo bench --bench bench_layer_map
To run a specific function:
cargo bench --bench bench_layer_map -- real_map_uniform_queries