REPLACE FUNCTION perl_set()
RETURNS SETOF testrowperl AS $$
    return_next({ f1 => 1, f2 => 'Hello', f3 => 'World' });
    return_next({ f1 => 2, f2 => 'Hello', f3 => 'PostgreSQL' });
    return_next({ f1 => 3, f2 => 'Hello', f3 => 'PL/Perl' });
    return undef;
$$ LANGUAGE plperl;
</programlisting>

    For small result sets, you can return a reference to an array that
    contains either scalars, references to arrays, or references to
    hashes for simple types, array types, and composite types,
    respectively.  Here are some simple examples of returning the entire
    result set as an array reference:

<programlisting>
CREATE OR REPLACE FUNCTION perl_set_int(int) RETURNS SETOF INTEGER AS $$
    return [0..$_[0]];
$$ LANGUAGE plperl;

SELECT * FROM perl_set_int(5);

CREATE OR REPLACE FUNCTION perl_set() RETURNS SETOF testrowperl AS $$
    return [
        { f1 =&gt; 1, f2 =&gt; 'Hello', f3 =&gt; 'World' },
        { f1 =&gt; 2, f2 =&gt; 'Hello', f3 =&gt; 'PostgreSQL' },
        { f1 =&gt; 3, f2 =&gt; 'Hello', f3 =&gt; 'PL/Perl' }
    ];
$$ LANGUAGE plperl;

SELECT * FROM perl_set();
</programlisting>
  </para>

  <para>
   If you wish to use the <literal>strict</literal> pragma with your code you
   have a few options. For temporary global use you can <command>SET</command>
   <literal>plperl.use_strict</literal> to true.
   This will affect subsequent compilations of <application>PL/Perl</application>
   functions, but not functions already compiled in the current session.
   For permanent global use you can set <literal>plperl.use_strict</literal>
   to true in the <filename>postgresql.conf</filename> file.
  </para>

  <para>
   For permanent use in specific functions you can simply put:
<programlisting>
use strict;
</programlisting>
   at the top of the function body.
  </para>

  <para>
  The <literal>feature</literal> pragma is also available to <function>use</function> if your Perl is version 5.10.0 or higher.
  </para>

 </sect1>

 <sect1 id="plperl-data">
  <title>Data Values in PL/Perl</title>

  <para>
   The argument values supplied to a PL/Perl function's code are
   simply the input arguments converted to text form (just as if they
   had been displayed by a <command>SELECT</command> statement).
   Conversely, the <function>return</function> and <function>return_next</function>
   commands will accept any string that is acceptable input format
   for the function's declared return type.
  </para>

  <para>
   If this behavior is inconvenient for a particular case, it can be
   improved by using a transform, as already illustrated
   for <type>bool</type> values.  Several examples of transform modules
   are included in the <productname>PostgreSQL</productname> distribution.
  </para>
 </sect1>

 <sect1 id="plperl-builtins">
  <title>Built-in Functions</title>

 <sect2 id="plperl-database">
  <title>Database Access from PL/Perl</title>

  <para>
   Access to the database itself from your Perl function can be done
   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>