On Wed, Oct 11, 2023 at 4:28 PM Thomas Munro <thomas.mu...@gmail.com> wrote: > That leaves only the segments where a record starts exactly on the > first usable byte of a segment, which is why I was trying to think of > a way to cover that case too. I suggested we could notice and insert > a new record at that place. But Andres suggests it would be too > expensive and not worth worrying about.
Hmm. Even in that case, xl_prev has to match. It's not like it's the wild west. Sure, it's not nearly as good of a cross-check, but it's something. It seems to me that it's not worth worrying very much about xlp_seg_size or xlp_blcksz changing undetected in that scenario - if you're doing that kind of advanced magic, you need to be careful enough to not mess it up, and if we still cross-check once per checkpoint cycle that's pretty good. I do worry a bit about the sysid changing under us, though. It's not that hard to get your WAL archives mixed up, and it'd be nice to catch that right away. -- Robert Haas EDB: http://www.enterprisedb.com
