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><H1
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><A
NAME="VIEW-PG-SETTINGS"
>47.66. <TT
CLASS="STRUCTNAME"
>pg_settings</TT
></A
></H1
><P
> The view <TT
CLASS="STRUCTNAME"
>pg_settings</TT
> provides access to
run-time parameters of the server. It is essentially an alternative
interface to the <A
HREF="sql-show.html"
>SHOW</A
>
and <A
HREF="sql-set.html"
>SET</A
> commands.
It also provides access to some facts about each parameter that are
not directly available from <TT
CLASS="COMMAND"
>SHOW</TT
>, such as minimum and
maximum values.
</P
><DIV
CLASS="TABLE"
><A
NAME="AEN98272"
></A
><P
><B
>Table 47-67. <TT
CLASS="STRUCTNAME"
>pg_settings</TT
> Columns</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><THEAD
><TR
><TH
>Name</TH
><TH
>Type</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>name</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Run-time configuration parameter name</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>setting</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Current value of the parameter</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>unit</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Implicit unit of the parameter</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>category</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Logical group of the parameter</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>short_desc</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>A brief description of the parameter</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>extra_desc</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Additional, more detailed, description of the parameter</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>context</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Context required to set the parameter's value (see below)</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>vartype</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Parameter type (<TT
CLASS="LITERAL"
>bool</TT
>, <TT
CLASS="LITERAL"
>enum</TT
>,
<TT
CLASS="LITERAL"
>integer</TT
>, <TT
CLASS="LITERAL"
>real</TT
>, or <TT
CLASS="LITERAL"
>string</TT
>)
</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>source</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Source of the current parameter value</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>min_val</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Minimum allowed value of the parameter (null for non-numeric
values)</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>max_val</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Maximum allowed value of the parameter (null for non-numeric
values)</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>enumvals</TT
></TD
><TD
><TT
CLASS="TYPE"
>text[]</TT
></TD
><TD
>Allowed values of an enum parameter (null for non-enum
values)</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>boot_val</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Parameter value assumed at server startup if the parameter is
not otherwise set</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>reset_val</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Value that <TT
CLASS="COMMAND"
>RESET</TT
> would reset the parameter to
in the current session</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>sourcefile</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Configuration file the current value was set in (null for
values set from sources other than configuration files, or when
examined by a non-superuser);
helpful when using <TT
CLASS="LITERAL"
>include</TT
> directives in configuration files</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>sourceline</TT
></TD
><TD
><TT
CLASS="TYPE"
>integer</TT
></TD
><TD
>Line number within the configuration file the current value was
set at (null for values set from sources other than configuration files,
or when examined by a non-superuser)
</TD
></TR
></TBODY
></TABLE
></DIV
><P
> There are several possible values of <TT
CLASS="STRUCTFIELD"
>context</TT
>.
In order of decreasing difficulty of changing the setting, they are:
</P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>internal</TT
></DT
><DD
><P
> 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 <TT
CLASS="COMMAND"
>initdb</TT
>.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>postmaster</TT
></DT
><DD
><P
> 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 <TT
CLASS="FILENAME"
>postgresql.conf</TT
> file, or passed on
the command line when starting the server. Of course, settings with any
of the lower <TT
CLASS="STRUCTFIELD"
>context</TT
> types can also be
set at server start time.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>sighup</TT
></DT
><DD
><P
> Changes to these settings can be made in
<TT
CLASS="FILENAME"
>postgresql.conf</TT
> without restarting the server.
Send a <SPAN
CLASS="SYSTEMITEM"
>SIGHUP</SPAN
> signal to the postmaster to
cause it to re-read <TT
CLASS="FILENAME"
>postgresql.conf</TT
> and apply
the changes. The postmaster will also forward the
<SPAN
CLASS="SYSTEMITEM"
>SIGHUP</SPAN
> signal to its child processes so that
they all pick up the new value.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>backend</TT
></DT
><DD
><P
> Changes to these settings can be made in
<TT
CLASS="FILENAME"
>postgresql.conf</TT
> without restarting the server;
they can also be set for a particular session in the connection request
packet (for example, via <SPAN
CLASS="APPLICATION"
>libpq</SPAN
>'s <TT
CLASS="LITERAL"
>PGOPTIONS</TT
>
environment variable). However, these settings never change in a
session after it is started. If you change them in
<TT
CLASS="FILENAME"
>postgresql.conf</TT
>, send a
<SPAN
CLASS="SYSTEMITEM"
>SIGHUP</SPAN
> signal to the postmaster to cause it to
re-read <TT
CLASS="FILENAME"
>postgresql.conf</TT
>. The new values will only
affect subsequently-launched sessions.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>superuser</TT
></DT
><DD
><P
> These settings can be set from <TT
CLASS="FILENAME"
>postgresql.conf</TT
>,
or within a session via the <TT
CLASS="COMMAND"
>SET</TT
> command; but only superusers
can change them via <TT
CLASS="COMMAND"
>SET</TT
>. Changes in
<TT
CLASS="FILENAME"
>postgresql.conf</TT
> will affect existing sessions
only if no session-local value has been established with <TT
CLASS="COMMAND"
>SET</TT
>.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>user</TT
></DT
><DD
><P
> These settings can be set from <TT
CLASS="FILENAME"
>postgresql.conf</TT
>,
or within a session via the <TT
CLASS="COMMAND"
>SET</TT
> command. Any user is
allowed to change his session-local value. Changes in
<TT
CLASS="FILENAME"
>postgresql.conf</TT
> will affect existing sessions
only if no session-local value has been established with <TT
CLASS="COMMAND"
>SET</TT
>.
</P
></DD
></DL
></DIV
><P
> See <A
HREF="config-setting.html"
>Section 18.1</A
> for more information about the various
ways to change these parameters.
</P
><P
> The <TT
CLASS="STRUCTNAME"
>pg_settings</TT
> view cannot be inserted into or
deleted from, but it can be updated. An <TT
CLASS="COMMAND"
>UPDATE</TT
> applied
to a row of <TT
CLASS="STRUCTNAME"
>pg_settings</TT
> is equivalent to executing
the <A
HREF="sql-set.html"
>SET</A
> command on that named
parameter. The change only affects the value used by the current
session. If an <TT
CLASS="COMMAND"
>UPDATE</TT
> is issued within a transaction
that is later aborted, the effects of the <TT
CLASS="COMMAND"
>UPDATE</TT
> command
disappear when the transaction is rolled back. Once the surrounding
transaction is committed, the effects will persist until the end of the
session, unless overridden by another <TT
CLASS="COMMAND"
>UPDATE</TT
> or
<TT
CLASS="COMMAND"
>SET</TT
>.
</P
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