Reading up on ANTLR
2 deep · digging since jun 25
- I rewrote PostHog's SQL parser, 70x faster, while barely looking at the code
PostHog's engineer used parallel Claude Code sessions to rewrite their SQL parser, achieving a 70x speedup by fuzzing against the old ANTLR-based parser as an oracle.
- I wrote a 70x faster SQL parser while barely looking at the code - PostHog
The author used AI agents to rewrite PostHog's SQL parser in Rust, achieving a 70x speedup (454x in production) via property-based testing and oracle-based development.