When logging to syslog and this is on (the default), then each message will be prefixed by an increasing sequence number (such as
). This circumvents the --- last message repeated N times --- suppression that many syslog implementations perform by default. In more modern syslog implementations, repeated message suppression can be configured (for example,
$RepeatedMsgReduction in rsyslog), so this might not be necessary. Also, you could turn this off if you actually want to suppress repeated messages.
This parameter can only be set in the postgresql.conf file or on the server command line.