Re: cataloguing NOT NULL constraints

References to past discussions and patches:

https://postgr.es/m/CAKOSWNkN6HSyatuys8xZxzRCR-KL1OkHS5-b9qd9bf1Rad3PLA@mail.gmail.com
https://www.postgresql.org/message-id/flat/1343682669-sup-2532@alvh.no-ip.org
https://www.postgresql.org/message-id/20160109030002.GA671800@alvherre.pgsql

I started this time around from the newest of my patches in those
threads, but the implementation has changed considerably from what's
there.

-- 
Álvaro Herrera               48°01'N 7°57'E  —  https://www.EnterpriseDB.com/