Robert Haas <robertmh...@gmail.com> writes: > I had that thought too, but I don't *think* it's the case. This > function acquires a lock on the oldest bucket page, then on the new > bucket page. We could deadlock if someone who holds a pin on the new > bucket page tries to take a content lock on the old bucket page. But > who would do that? The new bucket page isn't yet linked from the > metapage at this point, so no scan should do that. There can be no > concurrent writers during replay. I think that if someone else has the > new page pinned they probably should not be taking content locks on > other buffers at the same time.
Agreed, the core code shouldn't do that, but somebody doing random stuff with pageinspect functions could probably make a query do this. See [1]; unless we're going to reject that bug with "don't do that", I'm not too comfortable with this line of reasoning. regards, tom lane [1] https://www.postgresql.org/message-id/flat/17568-ef121b956ec1559c%40postgresql.org