SET
SET — change a run-time parameter
Synopsis
SET [ SESSION | LOCAL ] configuration_parameter { TO | = } { value | 'value' | DEFAULT }
SET [ SESSION | LOCAL ] TIME ZONE { value | 'value' | LOCAL | DEFAULT }
Description
The SET command changes run-time configuration parameters. Many of the run-time
parameters listed in Chapter Server Configuration can be changed on-the-fly
with SET. (Some parameters can only be changed by superusers and users who have
been granted SET privilege on that parameter. There are also parameters that
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 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.
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), 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.
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. Issuing
this outside of a transaction block emits a warning and otherwise has no effect.
configuration_parameter
Name of a settable run-time parameter. Available parameters are documented in Chapter Server Configuration and below.
value
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. 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 Chapter Server Configuration,
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 inclusive.
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:
- 'America/Los_Angeles'
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).
Timezone settings given as numbers or intervals are internally translated to
POSIX timezone syntax. For example, after SET TIME ZONE -7, SHOW TIME ZONE
would report <-07>+07.
Time zone abbreviations are not supported by SET; see Section Time Zones for
more information about time zones.
Notes
The function set_config provides equivalent functionality; see Section
Configuration Settings Functions. 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 'America/Los_Angeles';
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 QHB allows more flexible
time-zone specifications. All other SET features are QHB
extensions.