0b1fe1413e
Each of max_connections, max_worker_processes, autovacuum_max_workers, and max_wal_senders has a GUC check hook that verifies the sum of those GUCs does not exceed a hard-coded limit (see the comment for MAX_BACKENDS in postmaster.h). In general, the hooks effectively guard against egregious misconfigurations. However, this approach has some problems. Since these check hooks are called as each GUC is assigned its user-specified value, only one of the hooks will be called with all the relevant GUCs set. If one or more of the user-specified values are less than the initial values of the GUCs' underlying variables, false positives can occur. Furthermore, the error message emitted when one of the check hooks fails is not tremendously helpful. For example, the command $ pg_ctl -D . start -o "-c max_connections=262100 -c max_wal_senders=10000" fails with the following error: FATAL: invalid value for parameter "max_wal_senders": 10000 Fortunately, there is an extra copy of this check in InitializeMaxBackends() that we can rely on, so this commit removes the aforementioned GUC check hooks in favor of that one. It also enhances the error message to clearly show the values of the relevant GUCs and the hard-coded limit their sum may not exceed. The downside of this change is that server startup progresses further before failing due to such misconfigurations (thus taking longer), but these failures are expected to be rare, so we don't anticipate any real harm in practice. Reviewed-by: Tom Lane Discussion: https://postgr.es/m/ZnMr2k-Nk5vj7T7H%40nathan
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/.