Horton

Re: Intermittent buildfarm failures on wrasse

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
Cc: Noah Misch <noah@leadboat.com>, Peter Geoghegan <pg@bowt.ie>, David Rowley <dgrowleyml@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-04-14T21:33:15Z
Lists: pgsql-hackers 
I wroteL
> Andres Freund <andres@anarazel.de> writes:
>> Thanks! Can you repro the problem manually on wrasse, perhaps even
>> outside the buildfarm script?

> I'm working on that right now, actually...

So far, reproducing it manually has been a miserable failure: I've
run about 180 cycles of the core regression tests with no error.
Not sure what's different between my test scenario and wrasse's.

Meanwhile, wrasse did fail with my relallvisible check in place [1],
and what that shows is that relallvisible is *zero* to start with
and remains so throughout the CREATE INDEX sequence.  That pretty
definitively proves that it's not a page-skipping problem but
an xmin-horizon-too-old problem.  We're no closer to understanding
where that horizon value is coming from, though.

			regards, tom lane

[1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=wrasse&dt=2022-04-14%2019%3A28%3A12

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.