SETSET7SQL - Language StatementsSETchange a run-time parameter
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
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
),
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.
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.
ParametersSESSION
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 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 , there are a few that can only be
adjusted using the SET command or that have a
special syntax:
SCHEMASET SCHEMA 'value' is an alias for
SET search_path TO value. Only one
schema can be specified using this syntax.
NAMESSET 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 ZONESET 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).
LOCALDEFAULT
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 for more information
about time zones.
Notes
The function set_config provides equivalent
functionality; see .
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';
CompatibilitySET 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