PGDay UK2026

What does it take to build a Postgres proxy that applications can't tell apart from vanilla Postgres? In this talk, I share lessons from building Multigres, a horizontally-scalable Postgres proxy. We'll walk through the real compatibility challenges we faced: implementing COPY FROM STDIN as a streaming state machine, managing session state and transactions with connection pooling, preserving all 14 Postgres error diagnostic fields through a gRPC stack, handling TLS negotiation, forwarding NOTICE messages, and forwarding client startup parameters. Then we'll see how we used Postgres's own regression and isolation test suites to measure and prove what it truly means to be a transparent Postgres proxy.