The following Propel query:
    $c->addDescendingOrderByColumn(AnswerPeer::CREATED_AT);
    $c->setLimit(sfConfig::get('app_feed_max'));
    $c->addjoin(QuestionPeer::ID, AnswerPeer::ASK_QUESTION_ID);
    $c->addJoin(UserPeer::ID, AnswerPeer::USER_ID);
    $c->addSelectColumn(UserPeer::COLUMN);
    $c->addSelectColumn(QuestionPeer::COLUMN);
    $answers = AnswerPeer::doSelect($c);