From 8ec5f160b8765a30d8630528999987565d36fdbb Mon Sep 17 00:00:00 2001 From: Daniel Bauman Date: Thu, 7 May 2026 09:33:07 -0700 Subject: [PATCH v2] Update docs for log_collector about error cases. Logs sent to the logging collector are not guaranteed to be written to disk. While this may be obvious for anyone with a technical understanding of how logging in postgresql works this isn't obviuos to non-technical users of the db. This doc attempts to make it clear that it's not transactionally guaranteed that every committed transaction will be logged. --- doc/src/sgml/config.sgml | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 73cc0412330..da2b33a01d8 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -7058,14 +7058,19 @@ local0.* /var/log/postgresql - The logging collector is designed to never lose messages. This means - that in case of extremely high load, server processes could be + The logging collector is designed to avoid dropping messages even under high log volume. + This means that in case of extremely high load, server processes could be blocked while trying to send additional log messages when the collector has fallen behind. In contrast, syslog prefers to drop messages if it cannot write them, which means it may fail to log some messages in such cases but it will not block the rest of the system. + + The logging collector does not guarantee that log messages have reached durable storage. + A system crash, power loss, or an error while writing the log file + can result in messages being lost. + -- 2.50.1 (Apple Git-155)