Mark Hills <mark(at)xwax(dot)org> writes:
> On Wed, 8 Feb 2023, Laurenz Albe wrote:
>> It takes 30 seconds to schan the table and determine that all existing
>> rows satisky the constraint.
> But there's no existing data (note this is adding column, not constraint)
> Existing rows are guaranteed to satisfy the domain check, because the
> domain check is guaranteed to be immutable (per [1] in my original mail)
immutable != "will accept null".
There could be some more optimizations here, perhaps, but there aren't.
regards, tom lane