public function update($pa_options = null)
{
$this->_generateSortableValue();
// populate sort field
// invalidate get() prefetch cache
SearchResult::clearResultCacheForTable($this->tableName());
// Invalid entire labels-by-id cache since we can't know what entries pertain to the label we just changed
LabelableBaseModelWithAttributes::$s_labels_by_id_cache = array();
// Unset label cache entry for modified label only
unset(LabelableBaseModelWithAttributes::$s_label_cache[$this->getSubjectTableName()][$this->get($this->getSubjectKey())]);
return parent::update($pa_options);
}