```
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 rows = block.rows();
    element_count += rows;
    for (size_t i = 0; i < attributes.size(); ++i)
    {
        const auto & column = block.safeGetByPosition(i + 1);
        if (attributes[i])
        {
            MutableColumnPtr mutated = IColumn::mutate(std::move(attributes[i]));
            mutated->insertRangeFrom(*column.column, 0, column.column->size());
            attributes[i] = std::move(mutated);
        }
        else
            attributes[i] = column.column;
    }
    
    polygons.reserve(polygons.size() + rows);
    ids.reserve(ids.size() + rows);
    const auto & key = block.safeGetByPosition(0).column;
    extractPolygons(key);
}
void IPolygonDictionary::loadData()