On Tue, May 21, 2019 at 12:33:54PM +1200, David Rowley wrote: > I guess it's not impossible for pg_dump to fail on this even without > this change. If someone had increased the limit on an instance with > say 16k page to something over what TOAST_TUPLE_TARGET_MAIN would be > on a standard instance, then restoring onto the 8k page instance will > fail. Of course, that's less likely since it's a whole other factor > in the equation, and it's still not impossible, so maybe we need to > think about it harder.
Sure, this one would be possible as well. Much less likely I guess as I don't imagine a lot of our user base which perform upgrades to new instances by changing the page size. One way to trick that would be to use a ratio of the page size instead. I would imagine that changing compile-time constraints when moving to a new version increases since we have logical replication so as you can move things with close to zero downtime without relying on the physical page size. > I see this item has been moved to the "Nothing to do" section of the > open items list. I'd really like to see a few other people comment > before we go and ignore this. We only get 1 opportunity to release a > fix like this per year and it would be good to get further > confirmation if we want to leave this. Yes, I moved this item without seeing any replies. Anyway, it's really the kind of thing I'd rather not touch post beta, and I see disadvantages in doing what you and Pavan propose as well. There is as well the argument that tuple_toast_target is so specialized that close to zero people are using it, hence changing its lower bound would impact nobody. > In my view, someone who has to go to the trouble of changing this > setting is probably going to have quite a bit of data in their > database and is quite unlikely to be using pg_dump due to that. Does > that mean we can make this cause an ERROR?... I don't know, but would > be good to hear what others think. Sure. Other opinions are welcome. Perhaps I lack insight and user stories on the matter, but I unfortunately see downsides in all things discussed. I am a rather pessimistic guy by nature. -- Michael
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