FROM pg_catalog.pg_class c
    LEFT JOIN pg_catalog.pg_namespace n ON (n.oid = c.relnamespace)
        WHERE c.relkind = 'm'
     ORDER BY 1
    LOOP

        -- Now "mviews" has one record with information about the materialized view

        RAISE NOTICE 'Refreshing materialized view %.% (owner: %)...',
                     quote_ident(mviews.mv_schema),
                     quote_ident(mviews.mv_name),
                     quote_ident(mviews.owner);
        EXECUTE format('REFRESH MATERIALIZED VIEW %I.%I', mviews.mv_schema, mviews.mv_name);
    END LOOP;

    RAISE NOTICE 'Done refreshing materialized views.';
    RETURN 1;
END;
$$ LANGUAGE plpgsql;
</programlisting>

     If the loop is terminated by an <literal>EXIT</literal> statement, the last
     assigned row value is still accessible after the loop.
    </para>

    <para>
     The <replaceable>query</replaceable> used in this type of <literal>FOR</literal>
     statement can be any SQL command that returns rows to the caller:
     <command>SELECT</command> is the most common case,
     but you can also use <command>INSERT</command>, <command>UPDATE</command>,
     <command>DELETE</command>, or <command>MERGE</command> with a
     <literal>RETURNING</literal> clause.  Some utility
     commands such as <command>EXPLAIN</command> will work too.
    </para>

    <para>
     <application>PL/pgSQL</application> variables are replaced by query parameters,
     and the query plan is cached for possible re-use, as discussed in
     detail in <xref linkend="plpgsql-var-subst"/> and
     <xref linkend="plpgsql-plan-caching"/>.
    </para>

    <para>
     The <literal>FOR-IN-EXECUTE</literal> statement is another way to iterate over
     rows:
<synopsis>
<optional> &lt;&lt;<replaceable>label</replaceable>&gt;&gt; </optional>
FOR <replaceable>target</replaceable> IN EXECUTE <replaceable>text_expression</replaceable> <optional> USING <replaceable>expression</replaceable> <optional>, ... </optional> </optional> LOOP
    <replaceable>statements</replaceable>
END LOOP <optional> <replaceable>label</replaceable> </optional>;
</synopsis>
     This is like the previous form, except that the source query
     is specified as a string expression, which is evaluated and replanned
     on each entry to the <literal>FOR</literal> loop.  This allows the programmer to
     choose the speed of a preplanned query or the flexibility of a dynamic
     query, just as with a plain <command>EXECUTE</command> statement.
     As with <command>EXECUTE</command>, parameter values can be inserted
     into the dynamic command via <literal>USING</literal>.
    </para>

    <para>
     Another way to specify the query whose results should be iterated
     through is to declare it as a cursor.  This is described in
     <xref linkend="plpgsql-cursor-for-loop"/>.
    </para>
   </sect2>

   <sect2 id="plpgsql-foreach-array">
    <title>Looping through Arrays</title>

    <para>
     The <literal>FOREACH</literal> loop is much like a <literal>FOR</literal> loop,
     but instead of iterating through the rows returned by an SQL query,
     it iterates through the elements of an array value.
     (In general, <literal>FOREACH</literal> is meant for looping through
     components of a composite-valued expression; variants for looping
     through composites besides arrays may be added in future.)
     The <literal>FOREACH</literal> statement to loop over an array is:

<synopsis>
<optional> &lt;&lt;<replaceable>label</replaceable>&gt;&gt; </optional>
FOREACH <replaceable>target</replaceable> <optional> SLICE <replaceable>number</replaceable> </optional> IN ARRAY <replaceable>expression</replaceable> LOOP
    <replaceable>statements</replaceable>
END LOOP <optional> <replaceable>label</replaceable> </optional>;
</synopsis>
    </para>

    <para>
     Without <literal>SLICE</literal>, or if <literal>SLICE 0</literal> is specified,
     the loop iterates through individual elements of the array produced
     by