When logging_collector is enabled, this parameter sets the file names of the created log files. The value is treated as a strftime pattern, so
%-escapes can be used to specify time-varying file names. (Note that if there are any time-zone-dependent
%-escapes, the computation is done in the zone specified by log_timezone.) The supported
%-escapes are similar to those listed in the Open Group's
If you specify a file name without escapes, you should plan to use a log rotation utility to avoid eventually filling the entire disk. In releases prior to 8.4, if no
% escapes were present, PostgreSQL would append the epoch of the new log file's creation time, but this is no longer the case.
If CSV-format output is enabled in log_destination,
.csv will be appended to the timestamped log file name to create the file name for CSV-format output. (If
log_filename ends in
.log, the suffix is replaced instead.)
This parameter can only be set in the postgresql.conf file or on the server command line.