Date: Sat, 25 Apr 2015 15:16:17 -0400
From: Bruce Momjian <bruce@momjian.us>
To: "David G. Johnston" <david.g.johnston@gmail.com>
Cc: Kevin Grittner <kgrittn@ymail.com>, Peter Eisentraut <peter_e@gmx.net>,
 "pgsql-docs@postgresql.org" <pgsql-docs@postgresql.org>
Subject: Re: Add a new table for Transaction Isolation?
Message-ID: <20150425191617.GC17791@momjian.us>
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On Sat, Apr 25, 2015 at 11:33:36AM -0700, David G. Johnston wrote:
> On Sat, Apr 25, 2015 at 11:02 AM, Bruce Momjian <bruce@momjian.us> wrote:
> 
>     On Fri, Apr 24, 2015 at 08:40:40PM +0000, Kevin Grittner wrote:
>     > And, for reasons given above, I really question whether such a
>     > table doesn't do more harm than good.  Even those citing the paper
>     > by Berenson, et al., often miss the text in *that* paper about what
>     > the actual definition of serializable transactions in the standard
>     > is, and instead focus on the quick-to-read tables of how the
>     > misinterpretation of serializable transactions based on the
>     > standard's table of phenomena (which the paper dubs "ANOMALY
>     > SERIALIZABLE") differs from truly serializable behavior.
>     >
>     > People do love tables like this, which makes providing them
>     > tempting; but when a short, clean table is available they often
>     > seem less inclined to take the trouble to read the real information
>     > the table summarizes -- and they come away with distorted and
>     > incorrect ideas about the subject matter.
> 
>     I don't think we can abandon the table --- people have enough trouble
>     figuring this out, including me, and without the table, it will be even
>     harder.
> 
>     What I have done is to add two rows and one column to the table, and
>     changed the surrounding text to more clearly reference the table.  You
>     can see the output here, and the SGML patch is attached:
> 
>             http://momjian.us/expire/transaction-iso.html
> 
> 
> Need to add "Serialization Anomalies" to the previous section's definitions
> list.

Uh, I am afraid the problem is that "Serialization Anomalies" is kind of
defined by the standard in an odd way that is specific to serializable
mode, I think.  Kevin, is that true?

> ​Pondering whether something like: "Possible (not in PG)" and avoiding the
> additional rows would make reading the table easier.

Uh, that's an idea.  I thought visually having two separate lines was
cleaner.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + Everyone has their own god. +


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