SET — change a run-time parameter
SET [ SESSION | LOCAL ]configuration_parameter{ TO | = } {value| 'value' | DEFAULT } SET [ SESSION | LOCAL ] TIME ZONE {value| 'value' | LOCAL | DEFAULT }
The SET command changes run-time configuration parameters. Many of the run-time parameters listed in Chapter 20 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.
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.
SESSIONSpecifies that the command takes effect for the current session. (This is the default if neither SESSION nor LOCAL appears.)
LOCALSpecifies 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_parameterName of a settable run-time parameter. Available parameters are documented in Chapter 20 and below.
valueNew 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 20, there are a few that can only be adjusted using the SET command or that have a special syntax:
SCHEMASET SCHEMA ' is an alias for value'SET search_path TO . Only one schema can be specified using this syntax.value
NAMESSET NAMES is an alias for valueSET client_encoding TO .value
SEEDSets 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 ' is an alias for value'SET timezone TO '. The syntax value'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.
-7The time zone 7 hours west from UTC (equivalent to PDT). Positive values are east from UTC.
INTERVAL '-08:00' HOUR TO MINUTEThe time zone 8 hours west from UTC (equivalent to PST).
LOCALDEFAULTSet 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 8.5.3 for more information about time zones.
The function set_config provides equivalent functionality; see Section 9.27.1. Also, it is possible to UPDATE the pg_settings system view to perform the equivalent of SET.
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';
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.
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