```
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:
```
Columns attributes;
    
    std::vector<std::variant<
        UInt8,
        UInt16,
        UInt32,
        UInt64,
        UInt128,
        Int8,
        Int16,
        Int32,
        Int64,
        Decimal32,
        Decimal64,
        Decimal128,
        Float32,
        Float64,
        String>> null_values;
    size_t bytes_allocated = 0;
    size_t element_count = 0;
    mutable std::atomic<size_t> query_count{0};
    /** Extracts a list of polygons from a column according to input_type and point_type.
     *  The polygons are appended to the dictionary with the corresponding ids.
     */
    void extractPolygons(const ColumnPtr & column);
    
    static std::vector<Point> extractPoints(const Columns &key_columns);
};
}