Replacing Protobuf with Rust to go 5 times faster

Summary

Replacing Protobuf with Rust to go 5 times faster Jan 22nd, 2026Lev Kokotov PgDog is a proxy for scaling PostgreSQL. Under the hood, we use libpg_query to parse and understand SQL queries. Since PgDog is written in Rust, we use its Rust bindings to interface with the core C library. Those bindings use Protobuf (de)serialization to work uniformly across different programming languages, e.g., the popular Ruby pg_query gem. Protobuf is fast, but not using Protobuf is faster. We forked pg_query.rs and replaced Protobuf with direct C-to-Rust (and back to C) bindings, using bindgen and Claude-generated wrappers. This resulted in a 5x improvement in parsing queries, and a 10x improvement in deparsing (Postgres AST to SQL string conversion). Results You can reproduce these by cloning our fork and running the benchmark tests: Function Queries per second pg_query::parse (Protobuf) 613 pg_query::parse_raw (Direct C to Rust) 3357 (5.45x faster) pg_query::deparse (Protobuf) 759 pg_query::deparse_raw (Direct Rust to C) 7319 (9.64x faster) The process The first step is always profiling. We use samply, which integrates nicely with the Firefox profiler. Samply is a sampling profiler: it measures how much time code spends running CPU instructions in each function. It works by inspecting the application call stack thousands of times per second. The more time is spent inside a particular function (or span, as they are typically called), the slower that code is. This is how we discovered pg_query_parse_protobuf: This is the entrypoint to the libpg_query C library, used by all pg_query bindings. The function that wraps the actual Postgres parser, pg_query_raw_parse, barely registered on the flame graph. Parsing queries isn’t free, but the Postgres parser itself is very quick and has been optimized for a long time. With the hot spot identified, our first instinct was to do nothing and just add a cache. Caching mostly works Caching is a trade-off between memory and CPU utilization, and mem...