log_filename

doc html

<p>
        When <code class="varname">logging_collector</code> is enabled,
        this parameter sets the file names of the created log files.  The value
        is treated as a <code class="function">strftime</code> pattern,
        so <code class="literal">%</code>-escapes can be used to specify time-varying
        file names.  (Note that if there are
        any time-zone-dependent <code class="literal">%</code>-escapes, the computation
        is done in the zone specified
        by <a class="xref" href="/docs/18/runtime-config-logging.html#GUC-LOG-TIMEZONE">log_timezone</a>.)
        The supported <code class="literal">%</code>-escapes are similar to those
        listed in the Open Group's <a class="ulink" href="https://pubs.opengroup.org/onlinepubs/009695399/functions/strftime.html" target="_top">strftime
        </a> specification.
        Note that the system's <code class="function">strftime</code> is not used
        directly, so platform-specific (nonstandard) extensions do not work.
        The default is <code class="literal">postgresql-%Y-%m-%d_%H%M%S.log</code>.
       </p><p>
        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 <code class="literal">%</code> escapes were
        present, <span class="productname">PostgreSQL</span> would append
        the epoch of the new log file's creation time, but this is no
        longer the case.
       </p><p>
        If CSV-format output is enabled in <code class="varname">log_destination</code>,
        <code class="literal">.csv</code> will be appended to the timestamped
        log file name to create the file name for CSV-format output.
        (If <code class="varname">log_filename</code> ends in <code class="literal">.log</code>, the suffix is
        replaced instead.)
       </p><p>
        If JSON-format output is enabled in <code class="varname">log_destination</code>,
        <code class="literal">.json</code> will be appended to the timestamped
        log file name to create the file name for JSON-format output.
        (If <code class="varname">log_filename</code> ends in <code class="literal">.log</code>, the suffix is
        replaced instead.)
       </p><p>
        This parameter can only be set in the <code class="filename">postgresql.conf</code>
        file or on the server command line.
       </p>

documentation revision

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