SET(7) SQL Commands SET(7)NAME
SET - change a run-time parameter
SYNOPSIS
SET [ SESSION | LOCAL ] configuration_parameter { TO | = } { value | 'value' | DEFAULT }
SET [ SESSION | LOCAL ] TIME ZONE { timezone | LOCAL | DEFAULT }
DESCRIPTION
The SET command changes run-time configuration parameters. Many of the
run-time parameters listed in in the documentation 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.) SET only
affects the value used by the current session.
If SET (or equivalently SET SESSION) is issued within a transaction
that is later aborted, the effects of the SET 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 SET.
The effects of SET LOCAL last only till the end of the current transac‐
tion, 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.
The effects of SET or SET LOCAL are also canceled by rolling back to a
savepoint that is earlier than the command.
If SET LOCAL is used within a function that has a SET option for the
same variable (see CREATE FUNCTION [create_function(7)]), the effects
of the SET LOCAL command disappear at function exit; that is, the value
in effect when the function was called is restored anyway. This allows
SET LOCAL to be used for dynamic or repeated changes of a parameter
within a function, while still having the convenience of using the SET
option to save and restore the caller's value. However, a regular SET
command overrides any surrounding function's SET option; its effects
will persist unless rolled back.
Note: In PostgreSQL versions 8.0 through 8.2, the effects of a
SET LOCAL would be canceled by releasing an earlier savepoint,
or by successful exit from a PL/pgSQL exception block. This
behavior has been changed because it was deemed unintuitive.
PARAMETERS
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 is executed outside a BEGIN block, since the trans‐
action will end immediately.
configuration_parameter
Name of a settable run-time parameter. Available parameters are
documented in in the documentation and below.
value New value of parameter. Values can be specified as string con‐
stants, identifiers, numbers, or comma-separated lists of these,
as appropriate for the particular parameter. DEFAULT can be
written to specify resetting the parameter to its default value
(that is, whatever value it would have had if no SET had been
executed in the current session).
Besides the configuration parameters documented in in the documenta‐
tion, there are a few that can only be adjusted using the SET command
or that have a special syntax:
SCHEMA SET SCHEMA 'value' is an alias for SET search_path TO value.
Only one schema can be specified using this syntax.
NAMES SET NAMES value is an alias for SET client_encoding TO value.
SEED Sets the internal seed for the random number generator (the
function random). Allowed values are floating-point numbers
between -1 and 1, which are then multiplied by 231-1.
The seed can also be set by invoking the function setseed:
SELECT setseed(value);
TIME ZONE
SET TIME ZONE value is an alias for SET timezone TO value. The
syntax SET TIME ZONE allows special syntax for the time zone
specification. Here are examples of valid values:
'PST8PDT'
The time zone for Berkeley, California.
'Europe/Rome'
The time zone for Italy.
-7 The time zone 7 hours west from UTC (equivalent to PDT).
Positive values are east from UTC.
INTERVAL '-08:00' HOUR TO MINUTE
The time zone 8 hours west from UTC (equivalent to PST).
LOCAL
DEFAULT
Set the time zone to your local time zone (that is, the
server's default value of timezone; if this has not been
explicitly set anywhere, it will be the zone that the
server's operating system defaults to).
See in the documentation for more information about time zones.
NOTES
The function set_config provides equivalent functionality; see in the
documentation. Also, it is possible to UPDATE the pg_settings system
view to perform the equivalent of SET.
EXAMPLES
Set the schema search path:
SET search_path TO my_schema, public;
Set the style of date to traditional POSTGRES with ``day before month''
input convention:
SET datestyle TO postgres, dmy;
Set the time zone for Berkeley, California:
SET TIME ZONE 'PST8PDT';
Set the time zone for Italy:
SET TIME ZONE 'Europe/Rome';
COMPATIBILITY
SET TIME ZONE extends syntax defined in the SQL standard. The standard
allows only numeric time zone offsets while PostgreSQL allows more
flexible time-zone specifications. All other SET features are Post‐
greSQL extensions.
SEE ALSO
RESET [reset(7)], SHOW [show(7)]
SQL - Language Statements 2013-04-02 SET(7)
