static function getObjectsStructure($dbname = null)
    {
        $_this = self::getInstance();
        $dbname = $_this->buildEntityName($dbname);

        $known_structure = $_this->registry->getEntry($dbname, 'objectStructure');
        if ($known_structure) {
            return $known_structure;
        } else {
            $structure = $_this->buildObjectsStructure($dbname);
            $_this->registry->setEntry($dbname, $structure, 'objectStructure');
            return $structure;
        }
    }