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41th chunk of `doc/src/sgml/system-views.sgml`
2db1f582951f299d54b6287eb7f50f13a5379db2070aec200000000100000fac
    </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <!-- PGC_POSTMASTER -->
    <term><literal>postmaster</literal></term>
    <listitem>
     <para>
      These settings can only be applied when the server starts, so any change
      requires restarting the server.  Values for these settings are typically
      stored in the <filename>postgresql.conf</filename> file, or passed on
      the command line when starting the server.  Of course, settings with any
      of the lower <structfield>context</structfield> types can also be
      set at server start time.
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <!-- PGC_SIGHUP -->
    <term><literal>sighup</literal></term>
    <listitem>
     <para>
      Changes to these settings can be made in
      <filename>postgresql.conf</filename> without restarting the server.
      Send a <systemitem>SIGHUP</systemitem> signal to the postmaster to
      cause it to re-read <filename>postgresql.conf</filename> and apply
      the changes.  The postmaster will also forward the
      <systemitem>SIGHUP</systemitem> signal to its child processes so that
      they all pick up the new value.
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <!-- PGC_SU_BACKEND -->
    <term><literal>superuser-backend</literal></term>
    <listitem>
     <para>
      Changes to these settings can be made in
      <filename>postgresql.conf</filename> without restarting the server.
      They can also be set for a particular session in the connection request
      packet (for example, via <application>libpq</application>'s <literal>PGOPTIONS</literal>
      environment variable), but only if the connecting user is a superuser
      or has been granted the appropriate <literal>SET</literal> privilege.
      However, these settings never change in a session after it is started.
      If you change them in <filename>postgresql.conf</filename>, send a
      <systemitem>SIGHUP</systemitem> signal to the postmaster to cause it to
      re-read <filename>postgresql.conf</filename>.  The new values will only
      affect subsequently-launched sessions.
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <!-- PGC_BACKEND -->
    <term><literal>backend</literal></term>
    <listitem>
     <para>
      Changes to these settings can be made in
      <filename>postgresql.conf</filename> without restarting the server.
      They can also be set for a particular session in the connection request
      packet (for example, via <application>libpq</application>'s <literal>PGOPTIONS</literal>
      environment variable); any user can make such a change for their session.
      However, these settings never change in a session after it is started.
      If you change them in <filename>postgresql.conf</filename>, send a
      <systemitem>SIGHUP</systemitem> signal to the postmaster to cause it to
      re-read <filename>postgresql.conf</filename>.  The new values will only
      affect subsequently-launched sessions.
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <!-- PGC_SUSET -->
    <term><literal>superuser</literal></term>
    <listitem>
     <para>
      These settings can be set from <filename>postgresql.conf</filename>,
      or within a session via the <command>SET</command> command; but only superusers
      and users with the appropriate <literal>SET</literal> privilege
      can change them via <command>SET</command>.  Changes in
      <filename>postgresql.conf</filename> will affect existing sessions
      only if no session-local value has been established with <command>SET</command>.
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <!-- PGC_USERSET -->
    <term><literal>user</literal></term>
    <listitem>
     <para>
      These settings can be set from <filename>postgresql.conf</filename>,
      or within a session via the <command>SET</command> command.  Any user is
      allowed to change their session-local
Title: Context Types for PostgreSQL Settings
Summary
The text describes the different context types for PostgreSQL settings, including postmaster, sighup, superuser-backend, backend, superuser, and user, and explains how each type can be changed, such as by restarting the server, sending a SIGHUP signal, or using the SET command, and the corresponding privileges and configuration files required for each type.