On Wed, Jun 8, 2022 at 5:55 PM Peter Geoghegan <p...@bowt.ie> wrote: > > That's a problem, because if in that scenario you allow three 2704 > > byte items that don't need a heap TID and later you find you need to > > add a heap TID to one of those items, the result will be bigger than > > 2704 bytes, and then you can't fit three of them into a page. > > Seems you must be right. I'm guessing that the field "cabbage" was > originally a nonce value, as part of a draft patch you're working on?
I wasn't originally setting out to modify BTPageOpaqueData at all, just borrow some special space. See the "storing an explicit nonce" discussion and patch set. But when this regression failure turned up I said to myself, hmm, I think this is an unrelated bug. > I think that we should fix this on HEAD, on general principle. There > is no reason to believe that this is a live bug, so a backpatch seems > unnecessary. Yeah, I agree with not back-patching the fix, unless it turns out that there is some platform where the same issue occurs without any cabbage. I assume that if it happened on any common system someone would have complained about it by now, so probably it doesn't. I suppose we could try to enumerate plausibly different values of the quantities involved and see if any of the combinations look like they lead to a bad result. I'm not really sure how many things could plausibly be different, though, apart from MAXIMUM_ALIGNOF. -- Robert Haas EDB: http://www.enterprisedb.com
