protected static function _getKeyColumns()
{
$keys = parent::_getKeyColumns();
$md = static::_getMetadata();
$keyFields = isset($md->table['indexes'][self::PK_INDEX_NAME]['columns']) ? $md->table['indexes'][self::PK_INDEX_NAME]['columns'] : [];
foreach ($keyFields as $k => $field) {
$keyFields[$k] = $md->columnNames[$field];
}
return array_merge($keys, $keyFields);
}
