On Wed, Oct 21, 2020 at 12:00:23PM +0200, Michael Banck wrote: > The check was ported (or the concept of it adapted) from pgBackRest if I > remember correctly.
Okay, I did not know that. >> As things stand, I'd like to think that it would be much more useful >> to remove this check and to have one or two extra retries (the current >> code only has one). I don't like much the possibility of false >> positives for such critical checks, but as we need to live with what >> has been released, that looks like a good move for stable branches. > > Sounds good to me. I think some were advocating for locking the page > before re-reading. When I looked at it, the level of abstraction that > pg_basebackup has (just a list of files chopped up into blocks, no > notion of relations I think) made that non-trivial, but maybe still > possible for v14 and beyond. That's a API layer I was looking at here: https://www.postgresql.org/message-id/flat/CAOBaU_aVvMjQn=ge5qPiJOPMmOj5=ii3st5q0y+wulml5sr...@mail.gmail.com My guess is that we should be able to make use of that for base backups as well, but I also think that I'd rather let v13 go with more retries without depending on a new API layer, removing of the LSN check altogether. Thinking of it, that's actually roughly what I posted here, but without the PageGetLSN() bit in the refactored code. So I see a pretty good argument to address the stable branches with that, and study for the future a better API to govern them all: https://www.postgresql.org/message-id/20201020062432.ga30...@paquier.xyz -- Michael
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