On 2024-May-09, Bruce Momjian wrote: > However, I don't see it mentioned as a release note item in the commit > message or mentioned in our docs. I suppose the release note text would > be: > > Removing a PRIMARY KEY will remove the NOT NULL column specification > > Previously the NOT NULL specification would be retained. > > Do we have agreement that we want this release note item?
Yes. Maybe we want some others too (especially regarding inheritance, but also regarding the way we handle the constraints internally), and maybe in this one we want different wording. How about something like this: Removing a primary key constraint may change the nullability characteristic of the columns that the primary key covered. If explicit not-null constraints exist on the same column, then they continue to be /known not nullable/; otherwise they become /possibly nullable/. This is largely based on the SQL standard's language of a column descriptor having a "nullability characteristic", which for columns with not-null or primary key constraints is "known not null". I don't think we use those terms anywhere. I hope this isn't too confusing. The standard's text on this, in section "4.13 Columns, fields, and attributes", is Every column has a nullability characteristic that indicates whether the value from that column can be the null value. A nullability characteristic is either known not nullable or possibly nullable. -- Álvaro Herrera 48°01'N 7°57'E — https://www.EnterpriseDB.com/
