Chapter 50. Frontend/Backend Protocol

Table of Contents

Overview

Protocol

Message Data Types

Message Formats

NOTE: Written by Phil Thompson

Postgres uses a message-based protocol for communication between frontends and backends. The protocol is implemented over TCP/IP and also on Unix sockets. Postgres v6.3 introduced version numbers into the protocol. This was done in such a way as to still allow connections from earlier versions of frontends, but this document does not cover the protocol used by those earlier versions.

This document describes the initial version-numbered protocol, designated v1.0. Higher level features built on this protocol (for example, how libpq passes certain environment variables after the connection is established) are covered elsewhere.