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The problem report was about setting GUCs in the startup packet for a physical replication connection. Setting the GUC required an ACL check, which performed a lookup on pg_parameter_acl.parname. The catalog cache was hardwired to use DEFAULT_COLLATION_OID for texteqfast() and texthashfast(), but the database default collation was uninitialized because it's a physical walsender and never connects to a database. In versions 18 and later, this resulted in a NULL pointer dereference, while in version 17 it resulted in an ERROR. As the comments stated, using DEFAULT_COLLATION_OID was arbitrary anyway: if the collation actually mattered, it should have used the column's actual collation. (In the catalog, some text columns are the default collation and some are "C".) Fix by using C_COLLATION_OID, which doesn't require any initialization and is always available. When any deterministic collation will do, it's best to consistently use the simplest and fastest one, so this is a good idea anyway. Another problem was raised in the thread, which this commit doesn't fix (see second discussion link). Reported-by: Andrey Borodin <x4mmm@yandex-team.ru> Discussion: https://postgr.es/m/D18AD72A-5004-4EF8-AF80-10732AF677FA@yandex-team.ru Discussion: https://postgr.es/m/4524ed61a015d3496fc008644dcb999bb31916a7.camel%40j-davis.com Backpatch-through: 17
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/17/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/17/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/.