View file PF.Base/module/feed/install/version/3.6.0beta1.xml.php
<upgrade>
<sql><![CDATA[a:1:{s:7:"ADD_KEY";a:1:{s:11:"phpfox_feed";a:1:{s:7:"user_id";a:2:{i:0;s:5:"INDEX";i:1;a:3:{i:0;s:7:"user_id";i:1;s:14:"feed_reference";i:2;s:10:"time_stamp";}}}}}]]></sql>
</upgrade>