The protocol documentation states that the maximum length of a cancel key is 256 bytes. This starts checking for that limit in libpq. Otherwise third party backend implementations will probably start using more bytes anyway. We also start requiring that a protocol 3.0 connection does not send a longer cancel key, to make sure that servers don't start breaking old 3.0-only clients by accident. Finally this also restricts the minimum key length to 4 bytes (both in the protocol spec and in the libpq implementation). Author: Jelte Fennema-Nio <postgres@jeltef.nl> Reviewed-by: Jacob Champion <jchampion@postgresql.org> Discussion: https://www.postgresql.org/message-id/df892f9f-5923-4046-9d6f-8c48d8980b50@iki.fi Backpatch-through: 18
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/.