Am 24.03.2024 um 16:17 schrieb Tom Lane:
To do that, we'd have to remember that you'd said NULL, which we don't: the word is just discarded as a noise clause. Considering that this usage of NULL isn't even permitted by the SQL standard, that seems like a bit too much work.
If I understood correctly, only the NOT NULL expression gets remembered, but the NULL gets discarded. No, I do not quite get it. Somehow, it has to be decided whether to create a "check constraint" or not, but this information is not available any more when creating the primary key? Not even in some kind of intermediary catalogue?
"Considering that this usage of NULL isn't even permitted by the SQL standard" is in my opinion a strange argument. To me, it is similar as to say, well a column has a not null constraint and that must be enough, we do not check whether the data complies when inserting or updating. Sure, my example has lots more side effect than silently do the right thing.
Please do not get me wrong. I can totally understand that something needs to much work to implement. I am just puzzled.
