PostgreSQL 7.2.1 Documentation
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# SET

## Name

SET -- change a run-time parameter

## Synopsis

    SET variable { TO | = } { value | 'value' | DEFAULT }
    SET TIME ZONE { 'timezone' | LOCAL | DEFAULT }

### Inputs

`variable`

  A settable run-time parameter.

`value`

  New value of parameter. `DEFAULT` can be used to specify resetting the parameter to its default value. Lists of strings are allowed, but more complex constructs may need to be single or double quoted.

## Description

The SET command changes run-time configuration parameters. The following parameters can be altered:

CLIENT_ENCODING
NAMES

  Sets the multibyte client encoding. The specified encoding must be supported by the backend.

  This option is only available if PostgreSQL is build with multibyte support.

DATESTYLE

  Choose the date/time representation style. Two separate settings are made: the default date/time output and the interpretation of ambiguous input.

  The following are date/time output styles:

  ISO

    Use ISO 8601-style dates and times (`YYYY-MM-DD HH:MM:SS`). This is the default.

  SQL

    Use Oracle/Ingres-style dates and times. Note that this style has nothing to do with SQL (which mandates ISO 8601 style), the naming of this option is a historical accident.

  PostgreSQL

    Use traditional PostgreSQL format.

  German

    Use `dd.mm.yyyy` for numeric date representations.

  The following two options determine both a substyle of the "SQL" and "PostgreSQL" output formats and the preferred interpretation of ambiguous date input.

  European

    Use `dd/mm/yyyy` for numeric date representations.

  NonEuropean
  US

    Use `mm/dd/yyyy` for numeric date representations.

  A value for SET DATESTYLE can be one from the first list (output styles), or one from the second list (substyles), or one from each separated by a comma.

  Date format initialization may be done by:

  Setting the `PGDATESTYLE` environment variable. If PGDATESTYLE is set in the frontend environment of a client based on libpq, libpq will automatically set DATESTYLE to the value of PGDATESTYLE during connection start-up.
  Running postmaster using the option `-o -e` to set dates to the `European` convention.

  The `DateStyle` option is really only intended for porting applications. To format your date/time values to choice, use the `to_char` family of functions.

SEED

  Sets the internal seed for the random number generator.

  `value`

    The value for the seed to be used by the `random` function. Allowed values are floating-point numbers between 0 and 1, which are then multiplied by 231-1. This product will silently overflow if a number outside the range is used.

    The seed can also be set by invoking the `setseed` SQL function:

        SELECT setseed(value);

SERVER_ENCODING

  Sets the multibyte server encoding.

  This option is only available if PostgreSQL was built with multibyte support.

TIME ZONE
TIMEZONE

  Sets the default time zone for your session. Arguments can be an SQL time interval constant, an integer or double precision constant, or a string representing a time zone supported by the host operating system.

  The possible values for time zone depends on your operating system. For example, on Linux `/usr/share/zoneinfo` contains the database of time zones.

  Here are some valid values for time zone:

  'PST8PDT'

    Set the time zone for California.

  'Portugal'

    Set the time zone for Portugal.

  'Europe/Rome'

    Set the time zone for Italy.

  7

    Set the time zone to 7 hours offset west from GMT (equivalent to PDT).

  INTERVAL '08:00' HOUR TO MINUTE

    Set the time zone to 8 hours offset west from GMT (equivalent to PST).

  LOCAL
  DEFAULT

    Set the time zone to your local time zone (the one that your operating system defaults to).

  If an invalid time zone is specified, the time zone becomes GMT (on most systems anyway).

  If the `PGTZ` environment variable is set in the frontend environment of a client based on libpq, libpq will automatically set TIMEZONE to the value of `PGTZ` during connection start-up.

An extended list of other run-time parameters can be found in the Administrator's Guide.

Use SHOW to show the current setting of a parameters.

## Diagnostics

`SET VARIABLE`

  Message returned if successful.

`ERROR: not a valid option name: `name``

  The parameter you tried to set does not exist.

`ERROR: permission denied`

  You must be a superuser to have access to certain settings.

`ERROR: `name` can only be set at start-up`

  Some parameters are fixed once the server is started.

## Examples

Set the style of date to traditional PostgreSQL with European conventions:

    SET DATESTYLE TO PostgreSQL,European;

Set the time zone for Berkeley, California, using double quotes to preserve the uppercase attributes of the time zone specifier (note that the date/time format is ISO here):

    SET TIME ZONE "PST8PDT";
    SELECT CURRENT_TIMESTAMP AS today;

             today
    ------------------------
     1998-03-31 07:41:21-08

Set the time zone for Italy (note the required single or double quotes to handle the special characters):

    SET TIME ZONE 'Europe/Rome';
    SELECT CURRENT_TIMESTAMP AS today;

             today
    ------------------------
     1998-03-31 17:41:31+02

## Compatibility

### SQL92

The second syntax shown above (`SET TIME ZONE`) attempts to mimic SQL92. However, SQL allows only numeric time zone offsets. All other parameter settings as well as the first syntax shown above are a PostgreSQL extension.

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