SELECT smaller_polygons.id
FROM big_polygon
LEFT JOIN big_polygon smaller_polygons
ON ST_Within(ST_Centroid(smaller_polygons.wkb_geometry),big_polygon.wkb_geometry)

SELECT
    smaller_polygons.id
FROM smaller_polygons
INNER JOIN big_polygon
ON ST_Within(ST_Centroid(smaller_polygons.wkb_geometry),big_polygon.wkb_geometry)