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