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SET(5)
NAME
SET - change a run-time parameter
SYNOPSIS
SET [ SESSION | LOCAL ] variable { TO | = } { value | 'value' | DEFAULT }
SET [ SESSION | LOCAL ] TIME ZONE { timezone | LOCAL | DEFAULT }
INPUTS
SESSION
Specifies that the command takes effect for the current session.
(This is the default if neither SESSION nor LOCAL appears.)
LOCAL
Specifies that the command takes effect for only the current
transaction. After COMMIT or ROLLBACK, the session-level setting takes
effect again. Note that SET LOCAL will appear to have no effect if
it's executed outside a BEGIN block, since the transaction will end
immediately.
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. Many of the
run-time parameters listed in the Administrator's Guide can be changed on-
the-fly with SET. (But some require superuser privileges to change, and
others cannot be changed after server or session start.) Note that SET only
affects the value used by the current session.
If SET or SET SESSION is issued within a transaction that is later aborted,
the effects of the SET command disappear when the transaction is rolled
back. (This behavior represents a change from PostgreSQL versions prior to
7.3, where the effects of SET would not roll back after a later error.)
Once the surrounding transaction is committed, the effects will persist
until the end of the session, unless overridden by another SET.
The effects of SET LOCAL last only till the end of the current transaction,
whether committed or not. A special case is SET followed by SET LOCAL
within a single transaction: the SET LOCAL value will be seen until the end
of the transaction, but afterwards (if the transaction is committed) the
SET value will take effect.
Even with autocommit set to off, SET does not start a new transaction
block. See the autocommit section of the Administrator's Guide for details.
Here are additional details about a few of the parameters that can be set:
DATESTYLE
Choose the date/time representation style. Two separate settings are
involved: 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.
SET DATESTYLE affects interpretation of input and provides several standard
output formats. For applications needing different variations or tighter
control over input or output, consider using the to_char family of
functions.
There are several now-deprecated means for setting the date style in
addition to the normal methods of setting it via SET or a configuration-
file entry:
Setting the postmaster's PGDATESTYLE environment variable. (This will be
overridden by any of the other methods.)
Running postmaster using the option -o -e to set dates to the European
convention. (This overrides environment variables and configuration-file
entries.)
Setting the client's 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. This is equivalent to a manually issued SET DATESTYLE.
NAMES
SET NAMES is an alias for SET CLIENT_ENCODING.
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.
The seed can also be set by invoking the setseed SQL function:
SELECT setseed(value);
SERVER_ENCODING
Shows the server-side multibyte encoding. (At present, this parameter
can be shown but not set, because the encoding is determined at initdb
time.)
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 name recognized by the host operating
system.
Here are some typical values for time zone settings:
'PST8PDT'
Set the time zone for Berkeley, 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).
The available time zone names depend on your operating system. For example,
on Linux /usr/share/zoneinfo contains the database of time zones; the names
of the files in that directory can be used as parameters to this command.
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.
Use SHOW [show(5)] to show the current setting of a parameter.
DIAGNOSTICS
SET Message returned if successful.
ERROR: 'name is not a
The parameter you tried to set does not exist.
ERROR: 'name':
You must be a superuser to alter certain settings.
ERROR: 'name' cannot
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 quotes to preserve the
uppercase spelling of the time zone name (note that the date style is
PostgreSQL for this example):
SET TIME ZONE 'PST8PDT';
SELECT CURRENT_TIMESTAMP AS today;
today
------------------------------------
Tue Feb 26 07:32:21.42834 2002 PST
Set the time zone for Italy (note the required single quotes to handle the
special characters):
SET TIME ZONE 'Europe/Rome';
SELECT CURRENT_TIMESTAMP AS today;
today
-------------------------------
2002-10-08 05:39:35.008271+02
COMPATIBILITY
SQL92
SET TIME ZONE extends syntax defined in SQL9x. SQL9x allows only numeric
time zone offsets while PostgreSQL allows full time zone specifier strings
as well. All other SET features are PostgreSQL extensions.
SEE ALSO
The function set_config provides the equivalent capability. See
Miscellaneous Functions in the PostgreSQL User's Guide.
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Index for
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Alphabetical
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Top of
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