Horton

Re: Intermittent buildfarm failures on wrasse

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Peter Geoghegan <pg@bowt.ie>, Noah Misch <noah@leadboat.com>, David Rowley <dgrowleyml@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-04-15T04:50:27Z
Lists: pgsql-hackers 
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

Commits

  1. Repurpose PROC_COPYABLE_FLAGS as PROC_XMIN_FLAGS

  2. Tighten ComputeXidHorizons' handling of walsenders.

  3. Adjust VACUUM's removable cutoff log message.

  4. Temporarily add some probes of tenk1's relallvisible in create_index.sql.

  5. Set synchronous_commit=on in test_setup.sql.

  6. Rearrange core regression tests to reduce cross-script dependencies.

  7. snapshot scalability: Don't compute global horizons while building snapshots.