syslog_facility

Definition PG 18 manual

When logging to syslog is enabled, this parameter determines the syslog “facility” to be used. You can choose from LOCAL0, LOCAL1, LOCAL2, LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7; the default is LOCAL0. See also the documentation of your system's syslog daemon. This parameter can only be set in the postgresql.conf file or on the server command line.

How it works

syslog_facility sets the syslog "facility" to be used when syslog enabled. It selects the syslog routing facility only when syslog is listed in log_destination; the system logger maps that facility to storage or forwarding rules.

syslog_facility is a SIGHUP-context setting: a configuration reload activates the new server value without a restart; subsequent operations that consult it use the refreshed value.

It is active only when syslog appears in log_destination, after which the facility, ident, sequence, splitting, host daemon, and remote receiver jointly define record delivery.

Operational considerations

Editing syslog_facility without reloading configuration and verifying the effective value and subsequent behavior.

Changing PostgreSQL framing or identifiers without testing the host daemon and remote receiver as one pipeline.

Assuming syslog preserves unlimited message size, multiline boundaries, ordering, or repeated records by default.

Changing syslog_facility globally without a rollback plan and a client or operational compatibility test.

Workload guidance

OLAP: Test syslog_facility under bursty analytical messages and multiline plans so splitting or receiver limits do not destroy record boundaries.

OLTP: Set syslog_facility to match the receiving syslog daemon's routing, framing, deduplication, and message-size contract; validate failover and backpressure with the real collector.

SMALL: Prefer the host's established syslog convention for syslog_facility; avoid parallel local-file retention unless it has an explicit purpose and size limit.