public function getSubtreeContent($sourceId, $onlyIds = false)
{
$query = $this->handler->createSelectQuery();
$query->select($onlyIds ? 'node_id, contentobject_id, depth' : '*')->from($this->handler->quoteTable('ezcontentobject_tree'));
$this->applySubtreeLimitation($query, $sourceId);
$query->orderBy($this->handler->quoteColumn('depth', 'ezcontentobject_tree'))->orderBy($this->handler->quoteColumn('node_id', 'ezcontentobject_tree'));
$statement = $query->prepare();
$statement->execute();
$results = $statement->fetchAll($onlyIds ? PDO::FETCH_COLUMN | PDO::FETCH_GROUP : PDO::FETCH_ASSOC);
// array_map() is used to to map all elements stored as $results[$i][0] to $results[$i]
return $onlyIds ? array_map('reset', $results) : $results;
}