I wrote a 70x faster SQL parser while barely looking at the code
Summary
The author describes rewriting PostHog's SQL parser with AI-assisted development using Claude and ANTLR, achieving up to 454x faster parsing in production and ~70x on a laptop. The piece highlights test-driven development with property-based testing, prompt engineering, and shadow-mode validation to ensure parity with the existing parser. It also discusses implications for parser design and AI-assisted tooling.