Re: Potential G2-item cycles under serializable isolation

From: Peter Geoghegan <pg(at)bowt(dot)ie>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: Kevin Grittner <kgrittn(at)gmail(dot)com>, Jeff Davis <pgsql(at)j-davis(dot)com>, PostgreSQL mailing lists <pgsql-bugs(at)lists(dot)postgresql(dot)org>, Kyle Kingsbury <aphyr(at)jepsen(dot)io>
Subject: Re: Potential G2-item cycles under serializable isolation
Date: 2020-06-11 01:10:25
Message-ID: CAH2-Wzk=-gRrZP4mvsFeFN8VQDw2WNdS8AnJG8eX020Q7XSmMQ@mail.gmail.com
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On Mon, Jun 8, 2020 at 7:30 PM Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
> I'll try to write an isolationtester test tomorrow.

Attached is v3, which has an isolationtester test.

It also fixes an assertion failure that could happen in rare cases,
which was reported to me privately by Thomas. We now explicitly don't
go ahead with an XID when it precedes TransactionXmin.

I overstated the significance of the fact that the transaction aborts
in the case that we looked at. That isn't an essential part of the
anomaly. See the isolation test.

--
Peter Geoghegan

Attachment Content-Type Size
v3-0001-Avoid-update-conflict-out-serialization-anomalies.patch application/octet-stream 6.6 KB

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