protected function _schema($query, $fields = null) {
		$model = $query->model();
		$paths = $query->paths($this);
		$models = $query->models($this);
		$alias = $query->alias();
		$result = [];

		if (!$model) {
			foreach ($fields as $field => $value) {
				if (is_array($value)) {
					$result[$field] = array_keys($value);
				} else {
					$result[''][] = $field;
				}
			}
			return $result;
		}
		if (!$fields) {
			foreach ($paths as $alias => $relation) {
				$model = $models[$alias];
				$result[$relation] = $model::schema()->names();
			}
			return $result;
		}

		$unalias = function ($value) {
			if (is_object($value) && isset($value->scalar)) {
				$value = $value->scalar;
			}
			$aliasing = preg_split("/\s+as\s+/i", $value);
			return isset($aliasing[1]) ? $aliasing[1] : $value;
		};

		if (isset($fields[0])) {
			$raw = array_map($unalias, $fields[0]);
			unset($fields[0]);
		}

		$fields = isset($fields[$alias]) ? [$alias => $fields[$alias]] + $fields : $fields;

		foreach ($fields as $field => $value) {
			if (is_array($value)) {
				if (isset($value['*'])) {
					$relModel = $models[$field];
					$result[$paths[$field]] = $relModel::schema()->names();
				} else {
					$result[$paths[$field]] = array_map($unalias, array_keys($value));
				}
			}
		}

		if (isset($raw)) {
			$result[''] = isset($result['']) ? array_merge($raw, $result['']) : $raw;
		}
		return $result;
	}