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Document guc context values, and reference them from the config doc section. 

Tom Lane
This commit is contained in:
Bruce Momjian 2011-03-17 00:26:03 -04:00
parent 5b079cb248
commit e148443ddd
2 changed files with 99 additions and 5 deletions
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94
doc/src/sgml/catalogs.sgml
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@ -7628,7 +7628,7 @@
<row>
<entry><structfield>context</structfield></entry>
<entry><type>text</type></entry>
<entry>Context required to set the parameter's value</entry>
<entry>Context required to set the parameter's value (see below)</entry>
</row>
<row>
<entry><structfield>vartype</structfield></entry>
@ -7692,6 +7692,98 @@
</tgroup>
</table>
<para>
There are several possible values of <structfield>context</structfield>.
In order of decreasing difficulty of changing the setting, they are:
</para>
<variablelist>
<varlistentry>
<term><literal>internal</literal></term>
<listitem>
<para>
These settings cannot be changed directly; they reflect internally
determined values. Some of them may be adjustable by rebuilding the
server with different configuration options, or by changing options
supplied to <command>initdb</command>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<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>
<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>
<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</>'s <literal>PGOPTIONS</>
environment variable). 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>
<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; but only superusers
can change them via <command>SET</>. Changes in
<filename>postgresql.conf</filename> will affect existing sessions
only if no session-local value has been established with <command>SET</>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<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. Any user is
allowed to change his session-local value. Changes in
<filename>postgresql.conf</filename> will affect existing sessions
only if no session-local value has been established with <command>SET</>.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
See <xref linkend="config-setting"> for more information about the various
ways to change these parameters.
</para>
<para>
The <structname>pg_settings</structname> view cannot be inserted into or
deleted from, but it can be updated. An <command>UPDATE</command> applied

10
doc/src/sgml/config.sgml
View File

@ -166,10 +166,12 @@ SET ENABLE_SEQSCAN TO OFF;
</para>
<para>
The virtual table <structname>pg_settings</structname>
(described in <xref linkend="view-pg-settings">) also allows
displaying and updating session run-time parameters. It is equivalent
to <command>SHOW</> and <command>SET</>, but can be more convenient
The virtual table <structname>pg_settings</structname> also allows
displaying and updating session run-time parameters; see <xref
linkend="view-pg-settings"> for details and a description of the
different variable types and when they can be changed.
<structname>pg_settings</structname> is equivalent to <command>SHOW</>
and <command>SET</>, but can be more convenient
to use because it can be joined with other tables, or selected from using
any desired selection condition. It also contains more information about
what values are allowed for the parameters.