pá 21. 8. 2026 v 19:13 odesílatel Tomas Vondra <[email protected]> napsal:
> > > On 8/21/26 17:47, Pavel Stehule wrote: > > Hi > > > > pá 21. 8. 2026 v 12:31 odesílatel Andrey Borodin <[email protected] > > <mailto:[email protected]>> napsal: > > > > Hi Pavel, > > > > On Thu, Aug 20, 2026 at 9:56 PM Pavel Stehule wrote: > > > We didn't find any way how this issue can be reproduced. We > manually > > > executed VACUUM on the database that was restored to the time close > > > before this issue - and the data was not broken - but now, I am not > > > sure what was the minor version that we used for this test. > > > > I wonder whether the missing TOAST data could be a secondary symptom, > > rather than evidence that VACUUM removed TOAST belonging to the > current > > row version. > > > > > > I have dumped pages > > > > https://www.postgresql.org/message-id/attachment/199738/ > > investigation.txt <https://www.postgresql.org/message-id/ > > attachment/199738/investigation.txt> > > > > xmin, xmax was same on main table, and toast table. These rows was not > > updated. > > > > Thanks. Interesting. It's weird the TOAST rows have XID 2779428784 and > flags {HEAP_HASVARWIDTH,HEAP_XMIN_COMMITTED,HEAP_XMAX_INVALID}, yet the > VACUUM apparently decided all of them are dead. Judging by: > > > rmgr: Heap2 len (rec/tot): 59/ 99, tx: 0, lsn: > > D6E/8A8A6AD0, prev D6E/8A8A6A68, desc: PRUNE latestRemovedXid 0 > > nredirected 0 ndead 4, blkref #0: rel 1663/4267629/16352341 blk > 17880358 FPW > > I mean, ndead=4 seems to suggest that. But how could that be with > HEAP_XMIN_COMMITTED? > > I wonder if the FPW from the WAL matches what you saw as corrupted, or > if it's correct (it should, given the ndead=4). But maybe try dumping it > using pg_waldump - although, 14 doesn't have that :-(. > > What happened with the XID 2779428784? Did it commit sometime right > before the vacuum, or what? Judging by the page LSN, it must have been > pretty far back. > > What does the clog say about this transaction? I think it should be: > pg_xact/0A5A, page 21, byte offset 175596, bits 0-1, so > > $ od -An -tx1 -j 175596 -N 1 $PGDATA/pg_xact/0A5A > > Also, what does the RUNNING_XACTS right before/after vacuum say? > Unfortunately these backups was overwritten month ago Regards Pavel > > -- > Tomas Vondra > >
