On Tue, Jan 10, 2023 at 8:34 AM Andres Freund <and...@anarazel.de> wrote: > A different approach would be to represent fxids as *signed* 64bit > integers. That'd of course loose more range, but could represent everything > accurately, and would have a compatible on-disk representation on two's > complement platforms (all our platforms). I think the only place that'd need > special treatment is U64FromFullTransactionId() / its callers. I think this > might be the most robust approach.
It does sound like an interesting approach; it means you are free to retreat arbitrarily without ever thinking about it, and by the arguments given (LSN space required to consume fxids) it's still 'enough'. Essentially all these bugs are places where the author already believed it worked that way. (Two's complement is required in the C23 draft.)
