```
SELECT *
FROM system.dictionaries
WHERE name LIKE 'XXXX%'

Row 1:
──────
database:                    default
name:                        XXXX_dict
uuid:                        00000000-0000-0000-0000-000000000000
status:                      LOADED
origin:                      default.XXXX_dict
type:                        Polygon
key:                         (Array(Array(Array(Array(Float64)))))
attribute.names:             ['name','id']
attribute.types:             ['String','String']
bytes_allocated:             0
query_count:                 0
hit_rate:                    1
element_count:               433731
load_factor:                 1
source:                      ClickHouse: default.XXXX
lifetime_min:                60
lifetime_max:                1800
loading_start_time:          2021-03-11 00:07:52
last_successful_update_time: 2021-03-11 00:08:24
loading_duration:            31.595
last_exception:
```
{
    const auto * ptr_multi_polygons = typeid_cast<const ColumnArray*>(column.get());
    if (!ptr_multi_polygons)
        throw Exception{"Expected a column containing arrays of polygons", ErrorCodes::TYPE_MISMATCH};
    offset.multi_polygon_offsets.assign(ptr_multi_polygons->getOffsets());
    const auto * ptr_polygons = typeid_cast<const ColumnArray*>(&ptr_multi_polygons->getData());
    if (!ptr_polygons)
        throw Exception{"Expected a column containing arrays of rings when reading polygons", ErrorCodes::TYPE_MISMATCH};
    offset.polygon_offsets.assign(ptr_polygons->getOffsets());
    const auto * ptr_rings = typeid_cast<const ColumnArray*>(&ptr_polygons->getData());
    if (!ptr_rings)
        throw Exception{"Expected a column containing arrays of points when reading rings", ErrorCodes::TYPE_MISMATCH};
    offset.ring_offsets.assign(ptr_rings->getOffsets());
    return ptr_rings->getDataPtr().get();
}
const IColumn * unrollSimplePolygons(const ColumnPtr & column, Offset & offset)