```
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:
```
{
    return this;
}
SlabsPolygonIndex::SlabsPolygonIndex(
    const std::vector<Polygon> & polygons)
    : log(&Poco::Logger::get("SlabsPolygonIndex")),
      sorted_x(uniqueX(polygons))
{
    indexBuild(polygons);
}
std::vector<Coord> SlabsPolygonIndex::uniqueX(const std::vector<Polygon> & polygons)
{
    std::vector<Coord> all_x;
    for (const auto & poly : polygons)
    {
        for (const auto & point : poly.outer())
            all_x.push_back(point.x());
        for (const auto & inner : poly.inners())
            for (const auto & point : inner)
                all_x.push_back(point.x());
    }
    
    std::sort(all_x.begin(), all_x.end());
    all_x.erase(std::unique(all_x.begin(), all_x.end()), all_x.end());
    LOG_TRACE(log, "Found {} unique x coordinates", all_x.size());
    return all_x;
}
void SlabsPolygonIndex::indexBuild(const std::vector<Polygon> & polygons)