| SET(7) - phpMan
SET(7) PostgreSQL 12.3 Documentation 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 Chapter 19 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 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 (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. 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 19 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 19, 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
2^31-1.
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).
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.
See Section 8.5.3 for more information about time zones.
NOTES
The function set_config provides equivalent functionality; see Section 9.26. 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 PostgreSQL extensions.
SEE ALSO
RESET(7), SHOW(7)
PostgreSQL 12.3 2020 SET(7)
|