From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: Michael Paquier <michael.paquier@gmail.com>,
        Thomas Munro <thomas.munro@gmail.com>,
        Stephen Frost <sfrost@snowman.net>,
        Alvaro Herrera <alvherre@2ndquadrant.com>,
        David Steele <david@pgmasters.net>,
        Dmitry Dolgov <9erthalion6@gmail.com>,
        Jakub Wartak <Jakub.Wartak@tomtom.com>,
        Tomas Vondra <tomas.vondra@enterprisedb.com>,
        pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: WIP: WAL prefetch (another approach)
In-reply-to: <20210429031409.quuhyjihk6hqbloe@alap3.anarazel.de>
References: 
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 <892344.1619054465@sss.pgh.pa.us>
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 <20210428163245.ff67pb2ii5irr5zr@alap3.anarazel.de>
 <2808045.1619628335@sss.pgh.pa.us>
 <CA+hUKGJ03Q-TmE8-JzAm04_1maYus6_kX7XB--JBh1K63agSbQ@mail.gmail.com>
 <2947529.1619652293@sss.pgh.pa.us>
 <20210429001224.cdkef4ybkw7gramv@alap3.anarazel.de>
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Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Wed, 28 Apr 2021 20:14:09 -0700"
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Date: Wed, 28 Apr 2021 23:39:38 -0400
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Andres Freund <andres@anarazel.de> writes:
> I was now able to reproduce the problem again, and I'm afraid that the
> bug I hit is likely separate from Tom's.

Yeah, I think so --- the symptoms seem quite distinct.

My score so far today on the G4 is:

12 error-free regression test cycles on b3ee4c503

(plus one more with shared_buffers set to 16MB, on the strength
of your previous hunch --- didn't fail for me though)

HEAD failed on the second run with the same symptom as before:

2021-04-28 22:57:17.048 EDT [50479] FATAL:  inconsistent page found, rel 1=
663/58183/69545, forknum 0, blkno 696
2021-04-28 22:57:17.048 EDT [50479] CONTEXT:  WAL redo at 4/B72D408 for He=
ap/INSERT: off 77 flags 0x00; blkref #0: rel 1663/58183/69545, blk 696 FPW

This seems to me to be pretty strong evidence that I'm seeing *something*
real.  I'm currently trying to isolate a specific commit to pin it on.
A straight "git bisect" isn't going to work because so many people had
broken so many different things right around that date :-(, so it may
take awhile to get a good answer.

			regards, tom lane