Current File : //opt/alt/postgresql11/usr/share/man/man7/SET.7
'\" t
.\" Title: SET
.\" Author: The PostgreSQL Global Development Group
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\" Date: 2017-11-06
.\" Manual: PostgreSQL 9.2.24 Documentation
.\" Source: PostgreSQL 9.2.24
.\" Language: English
.\"
.TH "SET" "7" "2017-11-06" "PostgreSQL 9.2.24" "PostgreSQL 9.2.24 Documentation"
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.SH "NAME"
SET \- change a run\-time parameter
.\" SET
.SH "SYNOPSIS"
.sp
.nf
SET [ SESSION | LOCAL ] \fIconfiguration_parameter\fR { TO | = } { \fIvalue\fR | \*(Aq\fIvalue\fR\*(Aq | DEFAULT }
SET [ SESSION | LOCAL ] TIME ZONE { \fItimezone\fR | LOCAL | DEFAULT }
.fi
.SH "DESCRIPTION"
.PP
The
\fBSET\fR
command changes run\-time configuration parameters\&. Many of the run\-time parameters listed in
Chapter 18, Server Configuration, in the documentation
can be changed on\-the\-fly with
\fBSET\fR\&. (But some require superuser privileges to change, and others cannot be changed after server or session start\&.)
\fBSET\fR
only affects the value used by the current session\&.
.PP
If
\fBSET\fR
(or equivalently
\fBSET SESSION\fR) is issued within a transaction that is later aborted, the effects of the
\fBSET\fR
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
\fBSET\fR\&.
.PP
The effects of
\fBSET LOCAL\fR
last only till the end of the current transaction, whether committed or not\&. A special case is
\fBSET\fR
followed by
\fBSET LOCAL\fR
within a single transaction: the
\fBSET LOCAL\fR
value will be seen until the end of the transaction, but afterwards (if the transaction is committed) the
\fBSET\fR
value will take effect\&.
.PP
The effects of
\fBSET\fR
or
\fBSET LOCAL\fR
are also canceled by rolling back to a savepoint that is earlier than the command\&.
.PP
If
\fBSET LOCAL\fR
is used within a function that has a
SET
option for the same variable (see
CREATE FUNCTION (\fBCREATE_FUNCTION\fR(7))), the effects of the
\fBSET LOCAL\fR
command disappear at function exit; that is, the value in effect when the function was called is restored anyway\&. This allows
\fBSET LOCAL\fR
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\*(Aqs value\&. However, a regular
\fBSET\fR
command overrides any surrounding function\*(Aqs
SET
option; its effects will persist unless rolled back\&.
.if n \{\
.sp
.\}
.RS 4
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.ps +1
\fBNote\fR
.ps -1
.br
.PP
In
PostgreSQL
versions 8\&.0 through 8\&.2, the effects of a
\fBSET LOCAL\fR
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\&.
.sp .5v
.RE
.SH "PARAMETERS"
.PP
SESSION
.RS 4
Specifies that the command takes effect for the current session\&. (This is the default if neither
SESSION
nor
LOCAL
appears\&.)
.RE
.PP
LOCAL
.RS 4
Specifies that the command takes effect for only the current transaction\&. After
\fBCOMMIT\fR
or
\fBROLLBACK\fR, the session\-level setting takes effect again\&. Note that
\fBSET LOCAL\fR
will appear to have no effect if it is executed outside a
\fBBEGIN\fR
block, since the transaction will end immediately\&.
.RE
.PP
\fIconfiguration_parameter\fR
.RS 4
Name of a settable run\-time parameter\&. Available parameters are documented in
Chapter 18, Server Configuration, in the documentation
and below\&.
.RE
.PP
\fIvalue\fR
.RS 4
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
\fBSET\fR
had been executed in the current session)\&.
.RE
.PP
Besides the configuration parameters documented in
Chapter 18, Server Configuration, in the documentation, there are a few that can only be adjusted using the
\fBSET\fR
command or that have a special syntax:
.PP
SCHEMA
.RS 4
SET SCHEMA \*(Aq\fIvalue\fR\*(Aq
is an alias for
SET search_path TO \fIvalue\fR\&. Only one schema can be specified using this syntax\&.
.RE
.PP
NAMES
.RS 4
SET NAMES \fIvalue\fR
is an alias for
SET client_encoding TO \fIvalue\fR\&.
.RE
.PP
SEED
.RS 4
Sets the internal seed for the random number generator (the function
\fBrandom\fR)\&. Allowed values are floating\-point numbers between \-1 and 1, which are then multiplied by 231\-1\&.
.sp
The seed can also be set by invoking the function
\fBsetseed\fR:
.sp
.if n \{\
.RS 4
.\}
.nf
SELECT setseed(\fIvalue\fR);
.fi
.if n \{\
.RE
.\}
.RE
.PP
TIME ZONE
.RS 4
SET TIME ZONE \fIvalue\fR
is an alias for
SET timezone TO \fIvalue\fR\&. The syntax
SET TIME ZONE
allows special syntax for the time zone specification\&. Here are examples of valid values:
.PP
\*(AqPST8PDT\*(Aq
.RS 4
The time zone for Berkeley, California\&.
.RE
.PP
\*(AqEurope/Rome\*(Aq
.RS 4
The time zone for Italy\&.
.RE
.PP
\-7
.RS 4
The time zone 7 hours west from UTC (equivalent to PDT)\&. Positive values are east from UTC\&.
.RE
.PP
INTERVAL \*(Aq\-08:00\*(Aq HOUR TO MINUTE
.RS 4
The time zone 8 hours west from UTC (equivalent to PST)\&.
.RE
.PP
LOCAL, DEFAULT
.RS 4
Set the time zone to your local time zone (that is, the server\*(Aqs default value of
\fItimezone\fR)\&.
.RE
.sp
See
Section 8.5.3, \(lqTime Zones\(rq, in the documentation
for more information about time zones\&.
.RE
.SH "NOTES"
.PP
The function
\fBset_config\fR
provides equivalent functionality; see
Section 9.26, \(lqSystem Administration Functions\(rq, in the documentation\&. Also, it is possible to UPDATE the
pg_settings
system view to perform the equivalent of
\fBSET\fR\&.
.SH "EXAMPLES"
.PP
Set the schema search path:
.sp
.if n \{\
.RS 4
.\}
.nf
SET search_path TO my_schema, public;
.fi
.if n \{\
.RE
.\}
.PP
Set the style of date to traditional
POSTGRES
with
\(lqday before month\(rq
input convention:
.sp
.if n \{\
.RS 4
.\}
.nf
SET datestyle TO postgres, dmy;
.fi
.if n \{\
.RE
.\}
.PP
Set the time zone for Berkeley, California:
.sp
.if n \{\
.RS 4
.\}
.nf
SET TIME ZONE \*(AqPST8PDT\*(Aq;
.fi
.if n \{\
.RE
.\}
.PP
Set the time zone for Italy:
.sp
.if n \{\
.RS 4
.\}
.nf
SET TIME ZONE \*(AqEurope/Rome\*(Aq;
.fi
.if n \{\
.RE
.\}
.SH "COMPATIBILITY"
.PP
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\&.
.SH "SEE ALSO"
\fBRESET\fR(7), \fBSHOW\fR(7)
Mini Shell