MIME-Version: 1.0
Content-Type: multipart/mixed;
 boundary="=_9a12b8ede7b4c551f02d794719bf04a8"
Content-Transfer-Encoding: 7bit
Date: Tue, 22 Jun 2021 18:06:49 +0300
From: Maxim Orlov <m.orlov@postgrespro.ru>
To: Greg Nancarrow <gregn4422@gmail.com>
Cc: Pavel Borisov <pashkin.elfe@gmail.com>, Michael Paquier
 <michael@paquier.xyz>, Pengchengliu <pengchengliu@tju.edu.cn>, Andres Freund
 <andres@anarazel.de>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Parallel scan with SubTransGetTopmostTransaction assert coredump
In-Reply-To: <09788181118f7bd8000d3bb097e0720f@postgrespro.ru>
References: 
 <CAJcOf-cJfLcgxwz8TeTZqWe3z2XdLkZAT8gHTwgHqHP9-Cb-Mw@mail.gmail.com>
 <AMkAGwA2DuDLiuCUBBPk1KoS.3.1621046249310.Hmail.2008202116@tju.edu.cn>
 <CAJcOf-eDcGVUx0+HjeYzj73AK+x2OOLEQLcfPn4ThEG9pwZpSw@mail.gmail.com>
 <000901d74b84$fa262890$ee7279b0$@tju.edu.cn>
 <CAJcOf-dD-428NkhDKm8GKTDVU97LYUeOd=RazhLR9boxO_ywsA@mail.gmail.com>
 <000801d74d16$150494c0$3f0dbe40$@tju.edu.cn>
 <CAJcOf-dVeKS2YJaS_BVdF7ghQ=xFj2d68TzGjYCvzo8cM0FtDQ@mail.gmail.com>
 <CAJcOf-c63QJ3X7geemcjtkd7ohHM1=7xJYuv8W6LLRAc9DNvOQ@mail.gmail.com>
 <YKswhdCNo6gwn2w2@paquier.xyz>
 <CAJcOf-cNLhA7iaUYAQqZ44tz3oHJoPxGRm1+tNE27iJXTXObzQ@mail.gmail.com>
 <CALT9ZEG4vzW1C=U4-AvgCA9=QEqVfrxaQ8PQ98CGNZ5LBG96kQ@mail.gmail.com>
 <CAJcOf-dX8ufSeCghz9Wg4CrtpJboCxtkqjtK6giLowkwaROcuQ@mail.gmail.com>
 <09788181118f7bd8000d3bb097e0720f@postgrespro.ru>
User-Agent: Roundcube Webmail/1.4.0
Message-ID: <08ae178b309c617a9701cbc7ed8a98f0@postgrespro.ru>
Archived-At: 
 <https://www.postgresql.org/message-id/08ae178b309c617a9701cbc7ed8a98f0%40postgrespro.ru>
Precedence: bulk

--=_9a12b8ede7b4c551f02d794719bf04a8
Content-Transfer-Encoding: 7bit
Content-Type: text/plain; charset=US-ASCII;
 format=flowed

The analysis in the beginning of the discussion seems to be right, but 
the fix v2 looks too invasive for me.

Personally, I'd like not to remove snapshot even if transaction is 
read-only. I propose to consider "xid < TransactionXmin" as a legit case 
and just promote xid to TransactionXmin.

It's annoying this old bug still not fixed. What do you think?
---
Best regards,
Maxim Orlov.
--=_9a12b8ede7b4c551f02d794719bf04a8
Content-Transfer-Encoding: base64
Content-Type: text/x-diff;
 name=v3-0001-PG14-Fix-parallel-worker-failed-assertion-and-coredump.patch
Content-Disposition: attachment;
 filename*0*=UTF-8''v3-0001-PG14-Fix-parallel-worker-failed-assertion-and-;
 filename*1*=coredump.patch;
 size=1178

ZGlmZiAtLWdpdCBhL3NyYy9iYWNrZW5kL2FjY2Vzcy90cmFuc2FtL3N1YnRyYW5zLmMgYi9zcmMv
YmFja2VuZC9hY2Nlc3MvdHJhbnNhbS9zdWJ0cmFucy5jCmluZGV4IDZhOGU1MjFmODk0Li5jZTdj
OTBhYTM4ZiAxMDA2NDQKLS0tIGEvc3JjL2JhY2tlbmQvYWNjZXNzL3RyYW5zYW0vc3VidHJhbnMu
YworKysgYi9zcmMvYmFja2VuZC9hY2Nlc3MvdHJhbnNhbS9zdWJ0cmFucy5jCkBAIC0yOSw2ICsy
OSw3IEBACiAjaW5jbHVkZSAicG9zdGdyZXMuaCIKIAogI2luY2x1ZGUgImFjY2Vzcy9zbHJ1Lmgi
CisjaW5jbHVkZSAiYWNjZXNzL3BhcmFsbGVsLmgiCiAjaW5jbHVkZSAiYWNjZXNzL3N1YnRyYW5z
LmgiCiAjaW5jbHVkZSAiYWNjZXNzL3RyYW5zYW0uaCIKICNpbmNsdWRlICJwZ190cmFjZS5oIgpA
QCAtMTUyLDYgKzE1MywyMSBAQCBTdWJUcmFuc0dldFRvcG1vc3RUcmFuc2FjdGlvbihUcmFuc2Fj
dGlvbklkIHhpZCkKIAlUcmFuc2FjdGlvbklkIHBhcmVudFhpZCA9IHhpZCwKIAkJCQlwcmV2aW91
c1hpZCA9IHhpZDsKIAorCS8qCisJICogV2UgbWF5IGhhdmUgZGlmZmVyZW50IHhtaW5zIGluIGFj
dGl2ZSBhbmQgdHJhbnNhY3Rpb24gc25hcHNob3RzIGluCisJICogcGFyYWxsZWwgd29ya2Vycy4g
QW5kIFRyYW5zYWN0aW9uWG1pbiBjYW4gYmUgcHJvbW90ZWQgdG8gdGhlIG1heCBvZiB0aGVtLgor
CSAqIFNvLCB3ZSBkbyB0aGlzIHRvIGF2b2lkIGFzc2VydCBiZWxvdyB3aGVuIHJlc3RvcmUgYWN0
aXZlIHNuYXBzaG90IHdpdGgKKwkgKiBsZXNzIHhtaW4gdmFsdWUuCisJICoKKwkgKiBYWFg6IHRo
ZSBzYW1lIG1heSBiZSBmaXhlZCBieSBwcm9oaWJpdGluZyByZWFkLW9ubHkgdHJhbnNhY3Rpb25z
IChsaWtlCisJICogcGFyYWxsZWwgc2NhbnMpIHRvIGluY3JlbWVudCBUcmFuc2FjdGlvblhtaW4u
CisJICovCisJaWYgKElzUGFyYWxsZWxXb3JrZXIoKSkKKwl7CisJCXhpZCA9IHhpZCA+IFRyYW5z
YWN0aW9uWG1pbiA/IHhpZCA6IFRyYW5zYWN0aW9uWG1pbjsKKwkJcGFyZW50WGlkID0geGlkOwor
CQlwcmV2aW91c1hpZCA9IHhpZDsKKwl9CiAJLyogQ2FuJ3QgYXNrIGFib3V0IHN0dWZmIHRoYXQg
bWlnaHQgbm90IGJlIGFyb3VuZCBhbnltb3JlICovCiAJQXNzZXJ0KFRyYW5zYWN0aW9uSWRGb2xs
b3dzT3JFcXVhbHMoeGlkLCBUcmFuc2FjdGlvblhtaW4pKTsKIAo=
--=_9a12b8ede7b4c551f02d794719bf04a8--