This table contains a column `parent_region` that contains the key of the nearest parent for the element.
ClickHouse supports the [hierarchical](external_dicts_dict_structure.md#hierarchical-dict-attr) property for [external dictionary](index.md) attributes. This property allows you to configure the hierarchical dictionary similar to described above.
The [dictGetHierarchy](../functions/ext_dict_functions.md#dictgethierarchy) function allows you to get the parent chain of an element.
For our example, the structure of dictionary can be the following: