~ubuntu-branches/ubuntu/trusty/postgresql-9.3/trusty-updates : contents of doc/src/sgml/html/sql-set.html at revision 27

~ubuntu-branches/ubuntu/trusty/postgresql-9.3/trusty-updates : (revision 27)
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><H1
><A
NAME="SQL-SET"
></A
>SET</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN81378"
></A
><H2
>Name</H2
>SET&nbsp;--&nbsp;change a run-time parameter</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN81383"
></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="AEN81389"
></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="AEN81424"
></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="AEN81529"
></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="AEN81537"
></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="AEN81549"
></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="AEN81556"
></A
><H2
>See Also</H2
><A
HREF="sql-reset.html"
>RESET</A
>, <A
HREF="sql-show.html"
>SHOW</A
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