This is similar to Zone Maps in Netezza.
<a href="https://www.ibm.com/docs/en/psfa/7.2.1?topic=statistics-zone-maps" rel="nofollow">https://www.ibm.com/docs/en/psfa/7.2.1?topic=statistics-zone...</a><p>Incidentally, Netezza was built on Postgres engine, years back.