ne 23. 8. 2026 v 1:59 odesílatel Peter Geoghegan <[email protected]> napsal:
> On Sat, Aug 22, 2026 at 10:25 AM Pavel Stehule <[email protected]> > wrote: > > Unfortunately these backups was overwritten month ago > > I thought that your complaint might be related to a recently reported > issue with subxact corruption: > > https://postgr.es/m/[email protected] > > That case involves a subtransaction that has already subcommitted > being forced to abort. This reminded me of what Tomas said about it > being weird that the TOAST table's entry appears to be for a > committing transaction, yet other evidence suggests that the same XID > aborted. > > I asked Opus 5 to build a test case (based on one from Andrey Borodin > on that other thread) that produces symptoms consistent with Pavel's > report. It succeeded in doing so -- see the attached patch adding > these tests. > > These tests fail, demonstrating the same symptoms (you might have to > comment-out an assertion in clog.c to allow the script to get as far > as executing the pageinspect steps that show those specific details). > With Bryan Green's bug fix patch from the other thread applied, the > tests all pass. > > Of course, I'm not claiming that this is incontrovertible proof that > Pavel's case was an example of this bug causing corruption in the > field; other bugs have had similar symptoms. For example, the snapshot > export bug I'm working on [1] can make committed subxacts temporarily > appear to have aborted, albeit on a standby (that one doesn't fit > Pavel's reported symptoms but isn't too far off). I still think this > explanation has a decent chance of being the correct one. > > With that said, Pavel should look at this test case and try to find > any factor that might rule this explanation out. It would be worth > working out which ERROR actually happened. We simulate an OOM or other > error using the test's subxact-after-childxids-transfer injection > point; we don't know what ERROR actually occurred in the field (if we > assume this really was the bug involved, then some specific error must > have triggered it). > > Question for Pavel: When I run the failing test, I see "WARNING: > AbortSubTransaction while in COMMIT state" in the test server logs. Do > any of the logs that you collected show that? If they do, then this > diagnosis is almost certainly correct. > I'll ask the customer - now he it out of office, but I afraid so logs from this time are already thrown but I remember so on same server we found a vaccum errors "cannot to freeze commtted xmax" - I don't know if this is related to this bug, but it was few weeks after problem with broken TOAST regards Pavel Regards Pavel > > [1] > https://postgr.es/m/CAH2-WzmHVeYY=pjz9x8DhhxVjXHX0pvoQ-MdiB1Tt6=o2gt...@mail.gmail.com > -- > Peter Geoghegan >
