David Rowley <dgrowleyml@xxxxxxxxx> writes: > On Tue, 5 Nov 2024 at 04:18, Tom Lane <tgl@xxxxxxxxxxxxx> wrote: >> A different idea that occurred to me while looking at this is: >> why have we got all this machinery to add and check a flag >> column, rather than arranging things so that the two input >> relations are "outer" and "inner" children of the SetOp? > I've no idea why it's not like that. The current design is quite > strange and feels dated. It might be worth making that change as even > if we gave joins better support for IS NOT DISTINCT FROM and made > INTERSECT use INNER JOIN instead and EXCEPT use anti join, we'd still > need nodeSetOp.c for INTERSECT ALL and EXCEPT ALL. Yeah. We'd still need it, and besides which it seems like a fairly small project, unlike the other thing which could take multiple years to get to an acceptable state. Of course, I might be overestimating the performance benefit we'd get. But I'm tempted to give it a try. regards, tom lane
