Re: Intermittent buildfarm failures on wrasse

Hi,

On 2022-04-14 22:40:51 -0400, Tom Lane wrote:
> Peter Geoghegan <pg@bowt.ie> writes:
> > Suppose that the bug was actually in 06f5295af6, "Add single-item
> > cache when looking at topmost XID of a subtrans XID". Doesn't that fit
> > your timeline just as well?
> 
> I'd dismissed that on the grounds that there are no subtrans XIDs
> involved in tenk1's contents.  However, if that patch was faulty
> enough, maybe it affected other cases besides the advertised one?
> I've not read it.

I was planning to complain about that commit, fwiw. Without so much as
an assertion verifying the cache is correct it seems quite dangerous to
me.

And looking at it, it has obvious wraparound issues... But that can't
matter here, obviously.

We also reach SubTransGetTopmostTransaction() from XactLockTableWait()
but I don't quite see how we reach that here either...

Greetings,

Andres Freund