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><H1
><A
NAME="SQL-SET"
></A
>SET</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN78675"
></A
><H2
>Name</H2
>SET -- change a run-time parameter</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN78680"
></A
><H2
>Synopsis</H2
><PRE
CLASS="SYNOPSIS"
>SET [ SESSION | LOCAL ] <TT
CLASS="REPLACEABLE"
><I
>configuration_parameter</I
></TT
> { TO | = } { <TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
> | '<TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
>' | DEFAULT }
SET [ SESSION | LOCAL ] TIME ZONE { <TT
CLASS="REPLACEABLE"
><I
>timezone</I
></TT
> | LOCAL | DEFAULT }</PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN78686"
></A
><H2
>Description</H2
><P
> The <TT
CLASS="COMMAND"
>SET</TT
> command changes run-time configuration
parameters. Many of the run-time parameters listed in
<A
HREF="runtime-config.html"
>Chapter 18</A
> can be changed on-the-fly with
<TT
CLASS="COMMAND"
>SET</TT
>.
(But some require superuser privileges to change, and others cannot
be changed after server or session start.)
<TT
CLASS="COMMAND"
>SET</TT
> only affects the value used by the current
session.
</P
><P
> If <TT
CLASS="COMMAND"
>SET</TT
> (or equivalently <TT
CLASS="COMMAND"
>SET SESSION</TT
>)
is issued within a transaction that is later aborted, the effects of the
<TT
CLASS="COMMAND"
>SET</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"
>SET</TT
>.
</P
><P
> The effects of <TT
CLASS="COMMAND"
>SET LOCAL</TT
> last only till the end of
the current transaction, whether committed or not. A special case is
<TT
CLASS="COMMAND"
>SET</TT
> followed by <TT
CLASS="COMMAND"
>SET LOCAL</TT
> within
a single transaction: the <TT
CLASS="COMMAND"
>SET LOCAL</TT
> value will be
seen until the end of the transaction, but afterwards (if the transaction
is committed) the <TT
CLASS="COMMAND"
>SET</TT
> value will take effect.
</P
><P
> The effects of <TT
CLASS="COMMAND"
>SET</TT
> or <TT
CLASS="COMMAND"
>SET LOCAL</TT
> are
also canceled by rolling back to a savepoint that is earlier than the
command.
</P
><P
> If <TT
CLASS="COMMAND"
>SET LOCAL</TT
> is used within a function that has a
<TT
CLASS="LITERAL"
>SET</TT
> option for the same variable (see
<A
HREF="sql-createfunction.html"
>CREATE FUNCTION</A
>),
the effects of the <TT
CLASS="COMMAND"
>SET LOCAL</TT
> command disappear at
function exit; that is, the value in effect when the function was called is
restored anyway. This allows <TT
CLASS="COMMAND"
>SET LOCAL</TT
> to be used for
dynamic or repeated changes of a parameter within a function, while still
having the convenience of using the <TT
CLASS="LITERAL"
>SET</TT
> option to save and
restore the caller's value. However, a regular <TT
CLASS="COMMAND"
>SET</TT
> command
overrides any surrounding function's <TT
CLASS="LITERAL"
>SET</TT
> option; its effects
will persist unless rolled back.
</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
> In <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> versions 8.0 through 8.2,
the effects of a <TT
CLASS="COMMAND"
>SET LOCAL</TT
> would be canceled by
releasing an earlier savepoint, or by successful exit from a
<SPAN
CLASS="APPLICATION"
>PL/pgSQL</SPAN
> exception block. This behavior
has been changed because it was deemed unintuitive.
</P
></BLOCKQUOTE
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN78721"
></A
><H2
>Parameters</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>SESSION</TT
></DT
><DD
><P
> Specifies that the command takes effect for the current session.
(This is the default if neither <TT
CLASS="LITERAL"
>SESSION</TT
> nor
<TT
CLASS="LITERAL"
>LOCAL</TT
> appears.)
</P
></DD
><DT
><TT
CLASS="LITERAL"
>LOCAL</TT
></DT
><DD
><P
> Specifies that the command takes effect for only the current
transaction. After <TT
CLASS="COMMAND"
>COMMIT</TT
> or <TT
CLASS="COMMAND"
>ROLLBACK</TT
>,
the session-level setting takes effect again. Note that
<TT
CLASS="COMMAND"
>SET LOCAL</TT
> will appear to have no effect if it is
executed outside a <TT
CLASS="COMMAND"
>BEGIN</TT
> block, since the
transaction will end immediately.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>configuration_parameter</I
></TT
></DT
><DD
><P
> Name of a settable run-time parameter. Available parameters are
documented in <A
HREF="runtime-config.html"
>Chapter 18</A
> and below.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
></DT
><DD
><P
> New value of parameter. Values can be specified as string
constants, identifiers, numbers, or comma-separated lists of
these, as appropriate for the particular parameter.
<TT
CLASS="LITERAL"
>DEFAULT</TT
> can be written to specify
resetting the parameter to its default value (that is, whatever
value it would have had if no <TT
CLASS="COMMAND"
>SET</TT
> had been executed
in the current session).
</P
></DD
></DL
></DIV
><P
> Besides the configuration parameters documented in <A
HREF="runtime-config.html"
>Chapter 18</A
>, there are a few that can only be
adjusted using the <TT
CLASS="COMMAND"
>SET</TT
> command or that have a
special syntax:
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>SCHEMA</TT
></DT
><DD
><P
><TT
CLASS="LITERAL"
>SET SCHEMA '<TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
>'</TT
> is an alias for
<TT
CLASS="LITERAL"
>SET search_path TO <TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
></TT
>. Only one
schema can be specified using this syntax.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>NAMES</TT
></DT
><DD
><P
><TT
CLASS="LITERAL"
>SET NAMES <TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
></TT
> is an alias for
<TT
CLASS="LITERAL"
>SET client_encoding TO <TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
></TT
>.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>SEED</TT
></DT
><DD
><P
> Sets the internal seed for the random number generator (the
function <CODE
CLASS="FUNCTION"
>random</CODE
>). Allowed values are
floating-point numbers between -1 and 1, which are then
multiplied by 2<SUP
>31</SUP
>-1.
</P
><P
> The seed can also be set by invoking the function
<CODE
CLASS="FUNCTION"
>setseed</CODE
>:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT setseed(<TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
>);</PRE
><P></P
></DD
><DT
><TT
CLASS="LITERAL"
>TIME ZONE</TT
></DT
><DD
><P
><TT
CLASS="LITERAL"
>SET TIME ZONE <TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
></TT
> is an alias
for <TT
CLASS="LITERAL"
>SET timezone TO <TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
></TT
>. The
syntax <TT
CLASS="LITERAL"
>SET TIME ZONE</TT
> allows special syntax
for the time zone specification. Here are examples of valid
values:
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>'PST8PDT'</TT
></DT
><DD
><P
> The time zone for Berkeley, California.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>'Europe/Rome'</TT
></DT
><DD
><P
> The time zone for Italy.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>-7</TT
></DT
><DD
><P
> The time zone 7 hours west from UTC (equivalent
to PDT). Positive values are east from UTC.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>INTERVAL '-08:00' HOUR TO MINUTE</TT
></DT
><DD
><P
> The time zone 8 hours west from UTC (equivalent
to PST).
</P
></DD
><DT
><TT
CLASS="LITERAL"
>LOCAL</TT
><BR><TT
CLASS="LITERAL"
>DEFAULT</TT
></DT
><DD
><P
> Set the time zone to your local time zone (that is, the
server's default value of <TT
CLASS="VARNAME"
>timezone</TT
>).
</P
></DD
></DL
></DIV
><P>
See <A
HREF="datatype-datetime.html#DATATYPE-TIMEZONES"
>Section 8.5.3</A
> for more information
about time zones.
</P
></DD
></DL
></DIV
><P>
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN78826"
></A
><H2
>Notes</H2
><P
> The function <CODE
CLASS="FUNCTION"
>set_config</CODE
> provides equivalent
functionality; see <A
HREF="functions-admin.html"
>Section 9.26</A
>.
Also, it is possible to UPDATE the
<A
HREF="view-pg-settings.html"
><TT
CLASS="STRUCTNAME"
>pg_settings</TT
></A
>
system view to perform the equivalent of <TT
CLASS="COMMAND"
>SET</TT
>.
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN78834"
></A
><H2
>Examples</H2
><P
> Set the schema search path:
</P><PRE
CLASS="PROGRAMLISTING"
>SET search_path TO my_schema, public;</PRE
><P>
</P
><P
> Set the style of date to traditional
<SPAN
CLASS="PRODUCTNAME"
>POSTGRES</SPAN
> with <SPAN
CLASS="QUOTE"
>"day before month"</SPAN
>
input convention:
</P><PRE
CLASS="SCREEN"
>SET datestyle TO postgres, dmy;</PRE
><P>
</P
><P
> Set the time zone for Berkeley, California:
</P><PRE
CLASS="SCREEN"
>SET TIME ZONE 'PST8PDT';</PRE
><P>
</P
><P
> Set the time zone for Italy:
</P><PRE
CLASS="SCREEN"
>SET TIME ZONE 'Europe/Rome';</PRE
><P></P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN78846"
></A
><H2
>Compatibility</H2
><P
> <TT
CLASS="LITERAL"
>SET TIME ZONE</TT
> extends syntax defined in the SQL
standard. The standard allows only numeric time zone offsets while
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> allows more flexible
time-zone specifications. All other <TT
CLASS="LITERAL"
>SET</TT
>
features are <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> extensions.
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN78853"
></A
><H2
>See Also</H2
><A
HREF="sql-reset.html"
>RESET</A
>, <A
HREF="sql-show.html"
>SHOW</A
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