CASE WHEN mz_places_min_zoom IS NOT NULL
THEN jsonb_build_object(
'country_capital', CASE WHEN tags->'capital' = 'yes' THEN TRUE END,
'region_capital', CASE WHEN tags->'state_capital' = 'yes' THEN TRUE END,
'min_zoom', mz_places_min_zoom
)
END AS __places_properties__,
https://github.com/tilezen/vector-datasource/blob/master/queries/planet_osm_point.jinja2#L26-L32
https://github.com/tilezen/vector-datasource/blob/master/queries.yaml#L12-L28