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postgres/doc/src/sgml/ref/alter_function.sgml
Alvaro Herrera 31eae6028e Allow CURRENT/SESSION_USER to be used in certain commands
Commands such as ALTER USER, ALTER GROUP, ALTER ROLE, GRANT, and the
various ALTER OBJECT / OWNER TO, as well as ad-hoc clauses related to
roles such as the AUTHORIZATION clause of CREATE SCHEMA, the FOR clause
of CREATE USER MAPPING, and the FOR ROLE clause of ALTER DEFAULT
PRIVILEGES can now take the keywords CURRENT_USER and SESSION_USER as
user specifiers in place of an explicit user name.

This commit also fixes some quite ugly handling of special standards-
mandated syntax in CREATE USER MAPPING, which in particular would fail
to work in presence of a role named "current_user".

The special role specifiers PUBLIC and NONE also have more consistent
handling now.

Also take the opportunity to add location tracking to user specifiers.

Authors: Kyotaro Horiguchi.  Heavily reworked by Álvaro Herrera.
Reviewed by: Rushabh Lathia, Adam Brightwell, Marti Raudsepp.
2015-03-09 15:41:54 -03:00

331 lines
11 KiB
Plaintext

<!--
doc/src/sgml/ref/alter_function.sgml
PostgreSQL documentation
-->
<refentry id="SQL-ALTERFUNCTION">
<indexterm zone="sql-alterfunction">
<primary>ALTER FUNCTION</primary>
</indexterm>
<refmeta>
<refentrytitle>ALTER FUNCTION</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>ALTER FUNCTION</refname>
<refpurpose>change the definition of a function</refpurpose>
</refnamediv>
<refsynopsisdiv>
<synopsis>
ALTER FUNCTION <replaceable>name</replaceable> ( [ [ <replaceable class="parameter">argmode</replaceable> ] [ <replaceable class="parameter">argname</replaceable> ] <replaceable class="parameter">argtype</replaceable> [, ...] ] )
<replaceable class="PARAMETER">action</replaceable> [ ... ] [ RESTRICT ]
ALTER FUNCTION <replaceable>name</replaceable> ( [ [ <replaceable class="parameter">argmode</replaceable> ] [ <replaceable class="parameter">argname</replaceable> ] <replaceable class="parameter">argtype</replaceable> [, ...] ] )
RENAME TO <replaceable>new_name</replaceable>
ALTER FUNCTION <replaceable>name</replaceable> ( [ [ <replaceable class="parameter">argmode</replaceable> ] [ <replaceable class="parameter">argname</replaceable> ] <replaceable class="parameter">argtype</replaceable> [, ...] ] )
OWNER TO { <replaceable>new_owner</replaceable> | CURRENT_USER | SESSION_USER }
ALTER FUNCTION <replaceable>name</replaceable> ( [ [ <replaceable class="parameter">argmode</replaceable> ] [ <replaceable class="parameter">argname</replaceable> ] <replaceable class="parameter">argtype</replaceable> [, ...] ] )
SET SCHEMA <replaceable>new_schema</replaceable>
<phrase>where <replaceable class="PARAMETER">action</replaceable> is one of:</phrase>
CALLED ON NULL INPUT | RETURNS NULL ON NULL INPUT | STRICT
IMMUTABLE | STABLE | VOLATILE | [ NOT ] LEAKPROOF
[ EXTERNAL ] SECURITY INVOKER | [ EXTERNAL ] SECURITY DEFINER
COST <replaceable class="parameter">execution_cost</replaceable>
ROWS <replaceable class="parameter">result_rows</replaceable>
SET <replaceable class="parameter">configuration_parameter</replaceable> { TO | = } { <replaceable class="parameter">value</replaceable> | DEFAULT }
SET <replaceable class="parameter">configuration_parameter</replaceable> FROM CURRENT
RESET <replaceable class="parameter">configuration_parameter</replaceable>
RESET ALL
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>ALTER FUNCTION</command> changes the definition of a
function.
</para>
<para>
You must own the function to use <command>ALTER FUNCTION</>.
To change a function's schema, you must also have <literal>CREATE</>
privilege on the new schema.
To alter the owner, you must also be a direct or indirect member of the new
owning role, and that role must have <literal>CREATE</literal> privilege on
the function's schema. (These restrictions enforce that altering the owner
doesn't do anything you couldn't do by dropping and recreating the function.
However, a superuser can alter ownership of any function anyway.)
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">name</replaceable></term>
<listitem>
<para>
The name (optionally schema-qualified) of an existing function.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">argmode</replaceable></term>
<listitem>
<para>
The mode of an argument: <literal>IN</>, <literal>OUT</>,
<literal>INOUT</>, or <literal>VARIADIC</>.
If omitted, the default is <literal>IN</>.
Note that <command>ALTER FUNCTION</command> does not actually pay
any attention to <literal>OUT</> arguments, since only the input
arguments are needed to determine the function's identity.
So it is sufficient to list the <literal>IN</>, <literal>INOUT</>,
and <literal>VARIADIC</> arguments.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">argname</replaceable></term>
<listitem>
<para>
The name of an argument.
Note that <command>ALTER FUNCTION</command> does not actually pay
any attention to argument names, since only the argument data
types are needed to determine the function's identity.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">argtype</replaceable></term>
<listitem>
<para>
The data type(s) of the function's arguments (optionally
schema-qualified), if any.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">new_name</replaceable></term>
<listitem>
<para>
The new name of the function.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">new_owner</replaceable></term>
<listitem>
<para>
The new owner of the function. Note that if the function is
marked <literal>SECURITY DEFINER</literal>, it will subsequently
execute as the new owner.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">new_schema</replaceable></term>
<listitem>
<para>
The new schema for the function.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>CALLED ON NULL INPUT</literal></term>
<term><literal>RETURNS NULL ON NULL INPUT</literal></term>
<term><literal>STRICT</literal></term>
<listitem>
<para><literal>CALLED ON NULL INPUT</literal> changes the function so
that it will be invoked when some or all of its arguments are
null. <literal>RETURNS NULL ON NULL INPUT</literal> or
<literal>STRICT</literal> changes the function so that it is not
invoked if any of its arguments are null; instead, a null result
is assumed automatically. See <xref linkend="sql-createfunction">
for more information.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>IMMUTABLE</literal></term>
<term><literal>STABLE</literal></term>
<term><literal>VOLATILE</literal></term>
<listitem>
<para>
Change the volatility of the function to the specified setting.
See <xref linkend="sql-createfunction"> for details.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal><optional> EXTERNAL </optional> SECURITY INVOKER</literal></term>
<term><literal><optional> EXTERNAL </optional> SECURITY DEFINER</literal></term>
<listitem>
<para>
Change whether the function is a security definer or not. The
key word <literal>EXTERNAL</literal> is ignored for SQL
conformance. See <xref linkend="sql-createfunction"> for more information about
this capability.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>LEAKPROOF</literal></term>
<listitem>
<para>
Change whether the function is considered leakproof or not.
See <xref linkend="sql-createfunction"> for more information about
this capability.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>COST</literal> <replaceable class="parameter">execution_cost</replaceable></term>
<listitem>
<para>
Change the estimated execution cost of the function.
See <xref linkend="sql-createfunction"> for more information.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>ROWS</literal> <replaceable class="parameter">result_rows</replaceable></term>
<listitem>
<para>
Change the estimated number of rows returned by a set-returning
function. See <xref linkend="sql-createfunction"> for more information.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable>configuration_parameter</replaceable></term>
<term><replaceable>value</replaceable></term>
<listitem>
<para>
Add or change the assignment to be made to a configuration parameter
when the function is called. If
<replaceable>value</replaceable> is <literal>DEFAULT</literal>
or, equivalently, <literal>RESET</literal> is used, the function-local
setting is removed, so that the function executes with the value
present in its environment. Use <literal>RESET
ALL</literal> to clear all function-local settings.
<literal>SET FROM CURRENT</> saves the session's current value of
the parameter as the value to be applied when the function is entered.
</para>
<para>
See <xref linkend="sql-set"> and
<xref linkend="runtime-config">
for more information about allowed parameter names and values.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>RESTRICT</literal></term>
<listitem>
<para>
Ignored for conformance with the SQL standard.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
To rename the function <literal>sqrt</literal> for type
<type>integer</type> to <literal>square_root</literal>:
<programlisting>
ALTER FUNCTION sqrt(integer) RENAME TO square_root;
</programlisting>
</para>
<para>
To change the owner of the function <literal>sqrt</literal> for type
<type>integer</type> to <literal>joe</literal>:
<programlisting>
ALTER FUNCTION sqrt(integer) OWNER TO joe;
</programlisting>
</para>
<para>
To change the schema of the function <literal>sqrt</literal> for type
<type>integer</type> to <literal>maths</literal>:
<programlisting>
ALTER FUNCTION sqrt(integer) SET SCHEMA maths;
</programlisting>
</para>
<para>
To adjust the search path that is automatically set for a function:
<programlisting>
ALTER FUNCTION check_password(text) SET search_path = admin, pg_temp;
</programlisting>
</para>
<para>
To disable automatic setting of <varname>search_path</> for a function:
<programlisting>
ALTER FUNCTION check_password(text) RESET search_path;
</programlisting>
The function will now execute with whatever search path is used by its
caller.
</para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
This statement is partially compatible with the <command>ALTER
FUNCTION</> 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 <literal>RESTRICT</> key word, which is optional in
<productname>PostgreSQL</>.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-createfunction"></member>
<member><xref linkend="sql-dropfunction"></member>
</simplelist>
</refsect1>
</refentry>