<para>
Controls whether huge pages are requested for the main shared memory
area. Valid values are <literal>try</literal> (the default),
- <literal>on</literal>, and <literal>off</literal>. With
+ <literal>on</literal>, and <literal>off</literal>.
+ This parameter can only be set at server start. With
<varname>huge_pages</varname> set to <literal>try</literal>, the
server will try to request huge pages, but fall back to the default if
that fails. With <literal>on</literal>, failure to request huge pages
platform, is generally discouraged because it typically requires
non-default kernel settings to allow for large allocations (see <xref
linkend="sysvipc"/>).
+ This parameter can only be set at server start.
</para>
</listitem>
</varlistentry>
however, it may be useful for debugging, when the
<literal>pg_dynshmem</literal> directory is stored on a RAM disk, or when
other shared memory facilities are not available.
+ This parameter can only be set at server start.
</para>
</listitem>
</varlistentry>
blocks to prefetch. If this value is specified without units, it is
taken as bytes.
The default is 512kB.
+ This parameter can only be set at server start.
</para>
</listitem>
</varlistentry>
</term>
<listitem>
<para>
- Record commit time of transactions. This parameter
- can only be set in <filename>postgresql.conf</filename> file or on the server
- command line. The default value is <literal>off</literal>.
+ Record commit time of transactions.
+ This parameter can only be set at server start.
+ The default value is <literal>off</literal>.
</para>
</listitem>
</varlistentry>
determines the program name used to identify
<productname>PostgreSQL</productname> messages in
the log. The default is <literal>PostgreSQL</literal>.
- This parameter can only be set in the <filename>postgresql.conf</filename>
- file or on the server command line.
+ This parameter can only be set at server start.
</para>
</listitem>
</varlistentry>