On Sun, Apr 3, 2022 at 11:53 AM Andres Freund <and...@anarazel.de> wrote: > We've had bugs in pg_upgrade where post-upgrade xid horizons weren't correctly > set. We've had bugs were indexes were corrupted during replay. > > The latter can be caught by wal_consistency_checking - but that's pretty > expensive. > > It seems $subject would have a chance of catching some of these bugs, as well > as exposing amcheck to a database with a bit more varied content?
I thought that Andrew Dunstan (CC'd) had a BF animal that did this setup. But I'm not sure if that ever ended up happening. I meant to tell the authors of verify_heapam() (also CC'd) that it really helped with my recent VACUUM project. While the assertions that I wrote in vacuumlazy.c might catch certain bugs like this, verify_heapam() is much more effective in practice. Let's say that an all-visible page (or all-frozen page) has XIDs from before relfrozenxid. Why should the next VACUUM (or any VACUUM) be able to observe the problem? A testing strategy that doesn't rely on these kinds of accidental details to catch bugs is far better than one that does. Definitely all in favor of using verify_heapam() to its full potential. So I'm +1 on your proposal. -- Peter Geoghegan
