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+<!--
+doc/src/sgml/ref/call.sgml
+PostgreSQL documentation
+-->
+
+<refentry id="sql-call">
+ <indexterm zone="sql-call">
+ <primary>CALL</primary>
+ </indexterm>
+
+ <refmeta>
+ <refentrytitle>CALL</refentrytitle>
+ <manvolnum>7</manvolnum>
+ <refmiscinfo>SQL - Language Statements</refmiscinfo>
+ </refmeta>
+
+ <refnamediv>
+ <refname>CALL</refname>
+ <refpurpose>invoke a procedure</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+<synopsis>
+CALL <replaceable class="parameter">name</replaceable> ( [ <replaceable class="parameter">argument</replaceable> ] [, ...] )
+</synopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para>
+ <command>CALL</command> executes a procedure.
+ </para>
+
+ <para>
+ If the procedure has any output parameters, then a result row will be
+ returned, containing the values of those parameters.
+ </para>
+ </refsect1>
+
+ <refsect1>
+ <title>Parameters</title>
+
+ <variablelist>
+ <varlistentry>
+ <term><replaceable class="parameter">name</replaceable></term>
+ <listitem>
+ <para>
+ The name (optionally schema-qualified) of the procedure.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><replaceable class="parameter">argument</replaceable></term>
+ <listitem>
+ <para>
+ An argument expression for the procedure call.
+ </para>
+
+ <para>
+ Arguments can include parameter names, using the syntax
+ <literal><replaceable class="parameter">name</replaceable> =&gt; <replaceable class="parameter">value</replaceable></literal>.
+ This works the same as in ordinary function calls; see
+ <xref linkend="sql-syntax-calling-funcs"/> for details.
+ </para>
+
+ <para>
+ Arguments must be supplied for all procedure parameters that lack
+ defaults, including <literal>OUT</literal> parameters. However,
+ arguments matching <literal>OUT</literal> parameters are not evaluated,
+ so it's customary to just write <literal>NULL</literal> for them.
+ (Writing something else for an <literal>OUT</literal> parameter
+ might cause compatibility problems with
+ future <productname>PostgreSQL</productname> versions.)
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>Notes</title>
+
+ <para>
+ The user must have <literal>EXECUTE</literal> privilege on the procedure in
+ order to be allowed to invoke it.
+ </para>
+
+ <para>
+ To call a function (not a procedure), use <command>SELECT</command> instead.
+ </para>
+
+ <para>
+ If <command>CALL</command> is executed in a transaction block, then the
+ called procedure cannot execute transaction control statements.
+ Transaction control statements are only allowed if <command>CALL</command>
+ is executed in its own transaction.
+ </para>
+
+ <para>
+ <application>PL/pgSQL</application> handles output parameters
+ in <command>CALL</command> commands differently;
+ see <xref linkend="plpgsql-statements-calling-procedure"/>.
+ </para>
+ </refsect1>
+
+ <refsect1>
+ <title>Examples</title>
+<programlisting>
+CALL do_db_maintenance();
+</programlisting>
+ </refsect1>
+
+ <refsect1>
+ <title>Compatibility</title>
+
+ <para>
+ <command>CALL</command> conforms to the SQL standard,
+ except for the handling of output parameters. The standard
+ says that users should write variables to receive the values
+ of output parameters.
+ </para>
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+
+ <simplelist type="inline">
+ <member><xref linkend="sql-createprocedure"/></member>
+ </simplelist>
+ </refsect1>
+</refentry>