path: root/doc/src/sgml/man7/ALTER_FUNCTION.7

'\" t
.\"     Title: ALTER FUNCTION
.\"    Author: The PostgreSQL Global Development Group
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 2024
.\"    Manual: PostgreSQL 16.2 Documentation
.\"    Source: PostgreSQL 16.2
.\"  Language: English
.\"
.TH "ALTER FUNCTION" "7" "2024" "PostgreSQL 16.2" "PostgreSQL 16.2 Documentation"
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.SH "NAME"
ALTER_FUNCTION \- change the definition of a function
.SH "SYNOPSIS"
.sp
.nf
ALTER FUNCTION \fIname\fR [ ( [ [ \fIargmode\fR ] [ \fIargname\fR ] \fIargtype\fR [, \&.\&.\&.] ] ) ]
    \fIaction\fR [ \&.\&.\&. ] [ RESTRICT ]
ALTER FUNCTION \fIname\fR [ ( [ [ \fIargmode\fR ] [ \fIargname\fR ] \fIargtype\fR [, \&.\&.\&.] ] ) ]
    RENAME TO \fInew_name\fR
ALTER FUNCTION \fIname\fR [ ( [ [ \fIargmode\fR ] [ \fIargname\fR ] \fIargtype\fR [, \&.\&.\&.] ] ) ]
    OWNER TO { \fInew_owner\fR | CURRENT_ROLE | CURRENT_USER | SESSION_USER }
ALTER FUNCTION \fIname\fR [ ( [ [ \fIargmode\fR ] [ \fIargname\fR ] \fIargtype\fR [, \&.\&.\&.] ] ) ]
    SET SCHEMA \fInew_schema\fR
ALTER FUNCTION \fIname\fR [ ( [ [ \fIargmode\fR ] [ \fIargname\fR ] \fIargtype\fR [, \&.\&.\&.] ] ) ]
    [ NO ] DEPENDS ON EXTENSION \fIextension_name\fR

where \fIaction\fR is one of:

    CALLED ON NULL INPUT | RETURNS NULL ON NULL INPUT | STRICT
    IMMUTABLE | STABLE | VOLATILE
    [ NOT ] LEAKPROOF
    [ EXTERNAL ] SECURITY INVOKER | [ EXTERNAL ] SECURITY DEFINER
    PARALLEL { UNSAFE | RESTRICTED | SAFE }
    COST \fIexecution_cost\fR
    ROWS \fIresult_rows\fR
    SUPPORT \fIsupport_function\fR
    SET \fIconfiguration_parameter\fR { TO | = } { \fIvalue\fR | DEFAULT }
    SET \fIconfiguration_parameter\fR FROM CURRENT
    RESET \fIconfiguration_parameter\fR
    RESET ALL
.fi
.SH "DESCRIPTION"
.PP
\fBALTER FUNCTION\fR
changes the definition of a function\&.
.PP
You must own the function to use
\fBALTER FUNCTION\fR\&. To change a function\*(Aqs schema, you must also have
CREATE
privilege on the new schema\&. To alter the owner, you must be able to
SET ROLE
to the new owning role, and that role must have
CREATE
privilege on the function\*(Aqs schema\&. (These restrictions enforce that altering the owner doesn\*(Aqt do anything you couldn\*(Aqt do by dropping and recreating the function\&. However, a superuser can alter ownership of any function anyway\&.)
.SH "PARAMETERS"
.PP
\fIname\fR
.RS 4
The name (optionally schema\-qualified) of an existing function\&. If no argument list is specified, the name must be unique in its schema\&.
.RE
.PP
\fIargmode\fR
.RS 4
The mode of an argument:
IN,
OUT,
INOUT, or
VARIADIC\&. If omitted, the default is
IN\&. Note that
\fBALTER FUNCTION\fR
does not actually pay any attention to
OUT
arguments, since only the input arguments are needed to determine the function\*(Aqs identity\&. So it is sufficient to list the
IN,
INOUT, and
VARIADIC
arguments\&.
.RE
.PP
\fIargname\fR
.RS 4
The name of an argument\&. Note that
\fBALTER FUNCTION\fR
does not actually pay any attention to argument names, since only the argument data types are needed to determine the function\*(Aqs identity\&.
.RE
.PP
\fIargtype\fR
.RS 4
The data type(s) of the function\*(Aqs arguments (optionally schema\-qualified), if any\&.
.RE
.PP
\fInew_name\fR
.RS 4
The new name of the function\&.
.RE
.PP
\fInew_owner\fR
.RS 4
The new owner of the function\&. Note that if the function is marked
SECURITY DEFINER, it will subsequently execute as the new owner\&.
.RE
.PP
\fInew_schema\fR
.RS 4
The new schema for the function\&.
.RE
.PP
DEPENDS ON EXTENSION \fIextension_name\fR
.br
NO DEPENDS ON EXTENSION \fIextension_name\fR
.RS 4
This form marks the function as dependent on the extension, or no longer dependent on that extension if
NO
is specified\&. A function that\*(Aqs marked as dependent on an extension is dropped when the extension is dropped, even if
CASCADE
is not specified\&. A function can depend upon multiple extensions, and will be dropped when any one of those extensions is dropped\&.
.RE
.PP
CALLED ON NULL INPUT
.br
RETURNS NULL ON NULL INPUT
.br
STRICT
.RS 4
CALLED ON NULL INPUT
changes the function so that it will be invoked when some or all of its arguments are null\&.
RETURNS NULL ON NULL INPUT
or
STRICT
changes the function so that it is not invoked if any of its arguments are null; instead, a null result is assumed automatically\&. See
CREATE FUNCTION (\fBCREATE_FUNCTION\fR(7))
for more information\&.
.RE
.PP
IMMUTABLE
.br
STABLE
.br
VOLATILE
.RS 4
Change the volatility of the function to the specified setting\&. See
CREATE FUNCTION (\fBCREATE_FUNCTION\fR(7))
for details\&.
.RE
.PP
[ EXTERNAL ] SECURITY INVOKER
.br
[ EXTERNAL ] SECURITY DEFINER
.RS 4
Change whether the function is a security definer or not\&. The key word
EXTERNAL
is ignored for SQL conformance\&. See
CREATE FUNCTION (\fBCREATE_FUNCTION\fR(7))
for more information about this capability\&.
.RE
.PP
PARALLEL
.RS 4
Change whether the function is deemed safe for parallelism\&. See
CREATE FUNCTION (\fBCREATE_FUNCTION\fR(7))
for details\&.
.RE
.PP
LEAKPROOF
.RS 4
Change whether the function is considered leakproof or not\&. See
CREATE FUNCTION (\fBCREATE_FUNCTION\fR(7))
for more information about this capability\&.
.RE
.PP
COST \fIexecution_cost\fR
.RS 4
Change the estimated execution cost of the function\&. See
CREATE FUNCTION (\fBCREATE_FUNCTION\fR(7))
for more information\&.
.RE
.PP
ROWS \fIresult_rows\fR
.RS 4
Change the estimated number of rows returned by a set\-returning function\&. See
CREATE FUNCTION (\fBCREATE_FUNCTION\fR(7))
for more information\&.
.RE
.PP
SUPPORT \fIsupport_function\fR
.RS 4
Set or change the planner support function to use for this function\&. See
Section\ \&38.11
for details\&. You must be superuser to use this option\&.
.sp
This option cannot be used to remove the support function altogether, since it must name a new support function\&. Use
\fBCREATE OR REPLACE FUNCTION\fR
if you need to do that\&.
.RE
.PP
\fIconfiguration_parameter\fR
.br
\fIvalue\fR
.RS 4
Add or change the assignment to be made to a configuration parameter when the function is called\&. If
\fIvalue\fR
is
DEFAULT
or, equivalently,
RESET
is used, the function\-local setting is removed, so that the function executes with the value present in its environment\&. Use
RESET ALL
to clear all function\-local settings\&.
SET FROM CURRENT
saves the value of the parameter that is current when
\fBALTER FUNCTION\fR
is executed as the value to be applied when the function is entered\&.
.sp
See
\fBSET\fR(7)
and
Chapter\ \&20
for more information about allowed parameter names and values\&.
.RE
.PP
RESTRICT
.RS 4
Ignored for conformance with the SQL standard\&.
.RE
.SH "EXAMPLES"
.PP
To rename the function
sqrt
for type
integer
to
square_root:
.sp
.if n \{\
.RS 4
.\}
.nf
ALTER FUNCTION sqrt(integer) RENAME TO square_root;
.fi
.if n \{\
.RE
.\}
.PP
To change the owner of the function
sqrt
for type
integer
to
joe:
.sp
.if n \{\
.RS 4
.\}
.nf
ALTER FUNCTION sqrt(integer) OWNER TO joe;
.fi
.if n \{\
.RE
.\}
.PP
To change the schema of the function
sqrt
for type
integer
to
maths:
.sp
.if n \{\
.RS 4
.\}
.nf
ALTER FUNCTION sqrt(integer) SET SCHEMA maths;
.fi
.if n \{\
.RE
.\}
.PP
To mark the function
sqrt
for type
integer
as being dependent on the extension
mathlib:
.sp
.if n \{\
.RS 4
.\}
.nf
ALTER FUNCTION sqrt(integer) DEPENDS ON EXTENSION mathlib;
.fi
.if n \{\
.RE
.\}
.PP
To adjust the search path that is automatically set for a function:
.sp
.if n \{\
.RS 4
.\}
.nf
ALTER FUNCTION check_password(text) SET search_path = admin, pg_temp;
.fi
.if n \{\
.RE
.\}
.PP
To disable automatic setting of
\fIsearch_path\fR
for a function:
.sp
.if n \{\
.RS 4
.\}
.nf
ALTER FUNCTION check_password(text) RESET search_path;
.fi
.if n \{\
.RE
.\}
.sp
The function will now execute with whatever search path is used by its caller\&.
.SH "COMPATIBILITY"
.PP
This statement is partially compatible with the
\fBALTER FUNCTION\fR
statement in the SQL standard\&. The standard allows more properties of a function to be modified, but does not provide the ability to rename a function, make a function a security definer, attach configuration parameter values to a function, or change the owner, schema, or volatility of a function\&. The standard also requires the
RESTRICT
key word, which is optional in
PostgreSQL\&.
.SH "SEE ALSO"
CREATE FUNCTION (\fBCREATE_FUNCTION\fR(7)), DROP FUNCTION (\fBDROP_FUNCTION\fR(7)), ALTER PROCEDURE (\fBALTER_PROCEDURE\fR(7)), ALTER ROUTINE (\fBALTER_ROUTINE\fR(7))