via the following functions:
  </para>

   <variablelist>
    <varlistentry>
     <term>
      <literal><function>spi_exec_query</function>(<replaceable>query</replaceable> [, <replaceable>limit</replaceable>])</literal>
      <indexterm>
       <primary>spi_exec_query</primary>
       <secondary>in PL/Perl</secondary>
      </indexterm>
     </term>
     <listitem>
      <para>
       <function>spi_exec_query</function> executes an SQL command and
returns the entire row set as a reference to an array of hash references.
If <replaceable>limit</replaceable> is specified and is greater than zero,
then <function>spi_exec_query</function> retrieves at
most <replaceable>limit</replaceable> rows, much as if the query included
a <literal>LIMIT</literal> clause.  Omitting <replaceable>limit</replaceable>
or specifying it as zero results in no row limit.
      </para>

      <para>
<emphasis>You should only use this command when you know
that the result set will be relatively small.</emphasis>  Here is an
example of a query (<command>SELECT</command> command) with the
optional maximum number of rows:

<programlisting>
$rv = spi_exec_query('SELECT * FROM my_table', 5);
</programlisting>
        This returns up to 5 rows from the table
        <literal>my_table</literal>.  If <literal>my_table</literal>
        has a column <literal>my_column</literal>, you can get that
        value from row <literal>$i</literal> of the result like this:
<programlisting>
$foo = $rv-&gt;{rows}[$i]-&gt;{my_column};
</programlisting>
       The total number of rows returned from a <command>SELECT</command>
       query can be accessed like this:
<programlisting>
$nrows = $rv-&gt;{processed}
</programlisting>
      </para>

      <para>
       Here is an example using a different command type:
<programlisting>
$query = "INSERT INTO my_table VALUES (1, 'test')";
$rv = spi_exec_query($query);
</programlisting>
       You can then access the command status (e.g.,
       <literal>SPI_OK_INSERT</literal>) like this:
<programlisting>
$res = $rv-&gt;{status};
</programlisting>
       To get the number of rows affected, do:
<programlisting>
$nrows = $rv-&gt;{processed};
</programlisting>
      </para>

      <para>
       Here is a complete example:
<programlisting>
CREATE TABLE test (
    i int,
    v varchar
);

INSERT INTO test (i, v) VALUES (1, 'first line');
INSERT INTO test (i, v) VALUES (2, 'second line');
INSERT INTO test (i, v) VALUES (3, 'third line');
INSERT INTO test (i, v) VALUES (4, 'immortal');

CREATE OR REPLACE FUNCTION test_munge() RETURNS SETOF test AS $$
    my $rv = spi_exec_query('select i, v from test;');
    my $status = $rv-&gt;{status};
    my $nrows = $rv-&gt;{processed};
    foreach my $rn (0 .. $nrows - 1) {
        my $row = $rv-&gt;{rows}[$rn];
        $row-&gt;{i} += 200 if defined($row-&gt;{i});
        $row-&gt;{v} =~ tr/A-Za-z/a-zA-Z/ if (defined($row-&gt;{v}));
        return_next($row);
    }
    return undef;
$$ LANGUAGE plperl;

SELECT * FROM test_munge();
</programlisting>
    </para>
    </listitem>
    </varlistentry>

    <varlistentry>
     <term>
      <literal><function>spi_query(<replaceable>command</replaceable>)</function></literal>
      <indexterm>
       <primary>spi_query</primary>
       <secondary>in PL/Perl</secondary>
      </indexterm>
     </term>
     <term>
      <literal><function>spi_fetchrow(<replaceable>cursor</replaceable>)</function></literal>
      <indexterm>
       <primary>spi_fetchrow</primary>
       <secondary>in PL/Perl</secondary>
      </indexterm>
     </term>
     <term>
      <literal><function>spi_cursor_close(<replaceable>cursor</replaceable>)</function></literal>
      <indexterm>
       <primary>spi_cursor_close</primary>
       <secondary>in PL/Perl</secondary>
      </indexterm>
     </term>

    <listitem>
    <para>
    <literal>spi_query</literal> and <literal>spi_fetchrow</literal>
    work together as a pair for row sets which might be large, or for cases
    where you wish to