The reasoning for why all the message formats are parseable without the explicit message length field is anachronistic; the real reason is that protocol version 2 did not have a message length field. There's nothing wrong with relying on the message length, like we do in the CopyData messags, even though it often still makes sense to have length fields for individual parts in messages. Discussion: https://www.postgresql.org/message-id/02a4eed2-98f0-4796-9d4f-12128ff44fe0@iki.fi
PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.