Nikhil Benesch <nikhil.benesch@gmail.com> writes:
> On Mon, Oct 4, 2021 at 1:48 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> My mental model of these things is that the target table is cross-joined
>> to the additional tables as though by a comma in FROM [...]
> Mine as well.
> I just managed to dredge up some history here though. Turns out you
> explicitly disabled this feature for 9.4 to make room for a future
> feature to allow left-joining the target table [0]. Is support for
> that feature still desired/planned? (If it's been permanently
> abandoned for whatever reason, then maybe it's safe just to revert
> 158b7fa?)
Ah-hah, I wondered whether we hadn't thought about this already,
but I'd not gotten around to researching it.
Not sure what to tell you about the state of the idea that the
target table could be re-specified in FROM/USING. I'm hesitant
to close the door on it permanently, because people do periodically
wish to be able to left-join the target to something else. But
the fact that no one's done anything about it for years suggests
that it's not that high on anyone's wish list.
regards, tom lane