Re: Potential G2-item cycles under serializable isolation

From: Tatsuo Ishii <ishii(at)sraoss(dot)co(dot)jp>
To: thomas(dot)munro(at)gmail(dot)com
Cc: andres(at)anarazel(dot)de, aphyr(at)jepsen(dot)io, pg(at)bowt(dot)ie, kgrittn(at)gmail(dot)com, pgsql(at)j-davis(dot)com, pgsql-bugs(at)lists(dot)postgresql(dot)org
Subject: Re: Potential G2-item cycles under serializable isolation
Date: 2020-06-13 05:45:34
Message-ID: 20200613.144534.578057646673657576.t-ishii@sraoss.co.jp
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> On Fri, Jun 12, 2020 at 10:14 AM Thomas Munro <thomas(dot)munro(at)gmail(dot)com> wrote:
>> Here's a new attempt at that. Attached, but I'll also just include
>> the new paragraph here because it's short:
>
> Slightly improved version, bringing some wording into line with
> existing documentation. s/SQL Standard/SQL standard/, and explicitly
> referring to "locking" implementations of RR and Ser (as we do already
> a few paragraphs earlier, when discussing MVCC). My intention is to
> push this to all branches in a couple of days if there is no other
> feedback. I propose to treat it as a defect, because I agree that
> it's weird and surprising that we don't mention SI, especially
> considering the history of the standard levels. I mean, I guess it's
> basically implied by all the stuff that section says about MVCC vs
> traditional locking systems, and it's a super well known fact in our
> hacker community, but not using the standard term of art is a strange
> omission.
>
> In future release perhaps we could entertain ideas like accepting the
> name SNAPSHOT ISOLATION, and writing some more use-friendly guidance,
> and possibly even reference the Generalized Isolation Level
> Definitions stuff. I think it'd be a bad idea to stop accepting
> REPEATABLE READ and inconvenience our users, though; IMHO it's
> perfectly OK to stick with the current interpretation of the spec
> while also acknowledging flaws and newer thinking through this new
> paragraph.

+1.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp

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