From parser combinators to hand-written TDOP: adopting sqlparser-rs at Readyset

If you've ever wondered why a query that runs fine in Postgres fails silently in a caching layer, the answer is usually in the parser. Here's the story of how a customer's BETWEEN query led us to replace the parser we'd shipped since day one, what we gained (4x throughput, 44% lower tail latency), and why the old approach was broken in ways that were hard to see.