On 09.09.22 19:58, Alvaro Herrera wrote:
There were a lot more problems in that submission than I at first realized, and I had to rewrite a lot of code in order to fix them. I have fixed all the user-visible problems I found in this version, and reviewed the tests results more carefully so I am now more confident that behaviourally it's doing the right thing; but
Reading through the SQL standard again, I think this patch goes a bit too far in folding NOT NULL and CHECK constraints together. The spec says that you need to remember whether a column was defined as NOT NULL, and that the commands DROP NOT NULL and SET NOT NULL only affect constraints defined in that way. In this implementation, a constraint defined as NOT NULL is converted to a CHECK (x IS NOT NULL) constraint and the original definition is forgotten.
Besides that, I think that users are not going to like that pg_dump rewrites their NOT NULL constraints into CHECK table constraints.
I suspect that this needs a separate contype for NOT NULL constraints that is separate from CONSTRAINT_CHECK.
