High-Speed PostgreSQL Binary Protocol Proxying

The connection lands like a gunshot—PostgreSQL clients speak in binary, and proxies must handle every byte without error. There is no room for guesses. The Postgres binary protocol follows a strict structure: message types, lengths, payloads. A proxy that sits between client and server must read, parse, and forward each packet with absolute fidelity.

Manpages give you the truth in black and white. Study libpq and psql behavior. Note the startup message containing parameters. Watch how authentication responses shift the conversation. Query and data messages flow next, each with exact formats defined by the official PostgreSQL protocol documentation. Misinterpret one field, and you break the session.

Binary protocol proxying is different from text-based protocols. Every integer is a big-endian fixed width. Every string is null-terminated. Control messages like Parse, Bind, Describe, and Execute chain together in a tight lifecycle. The proxy must mirror this lifecycle without adding latency or losing order. This includes faithfully relaying ReadyForQuery signals so the client knows when the backend is idle again.

Engineers building secure or load-balanced Postgres layers need fast, reliable parsing logic. Manpages outline fundamental message specs, but production proxying demands deep inspection and reassembly at wire speed. Tools that dump raw protocol data—like tcpdump with filters on Postgres ports—help verify that the proxy respects message boundaries. Detailed logging in development mode can catch subtle mismatches before they hit production.

The most common pain points: handling SSL negotiation transparently, supporting extended query mode without dropping parameters, and correctly proxying large COPY streams. If the proxy mishandles packet framing, your database connection will stall or corrupt data. Strong tests must cover every message type and handle disconnects cleanly.

Skilled binary protocol proxying opens the door to advanced features: intelligent routing between read replicas, real-time query shaping, and performance monitoring at the wire level. Postgres manpages and protocol docs are the foundation. Precision builds the tower.

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