Jerry Sievers <jerry@xxxxxxxxxxxxxxxx> writes: > I believe what's happening here is that the server doesn't realize > that the new column is going to have all nulls and that the check > constraint allows nulls. As such, the check evidently is being > evaluated for each row of the table. Yup, that's right. There are some corner cases that make that harder to optimize than it might look: * volatile functions in the constraint might possibly deliver different answers at different rows * if table is in fact empty, we should not throw an error, nor indeed evaluate the constraint even once (again, volatile functions...) regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
