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Re: Major features for 9.1

From: Oleg Bartunov <oleg(at)sai(dot)msu(dot)su>
To: Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>
Cc: Jeff Davis <pgsql(at)j-davis(dot)com>, josh(at)agliodbs(dot)com, peter_e(at)gmx(dot)net, pgsql-advocacy(at)postgresql(dot)org
Subject: Re: Major features for 9.1
Date: 2011-04-05 09:36:28
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-advocacy
Yes, SSI confuses me too. I used to use server sides includes in the eve 
of web. I think our SSI is a cool technology and wiki page is must to have.
But I'd like to see useful examples.


On Mon, 4 Apr 2011, Kevin Grittner wrote:

> Jeff Davis <pgsql(at)j-davis(dot)com> wrote:
>> On Mon, 2011-04-04 at 07:20 -0500, Kevin Grittner wrote:
>>>> a) a two-line explanation of what the feature is and why it's
>>>> valuable (for the release notes, etc.)
>>>> b) a wiki page with a more detailed explaination and examples
>>>> oriented towards the beginning-to-intermediate PostgreSQL user.
>>>> Volunteers?
>>> I volunteer for SSI.
>> The way I think about SSI is that it automatically detects live
>> race conditions in your SQL transactions at runtime; and protects
>> you by safely rolling some of them back (which can be retried
>> safely).
>> Maybe something along those lines?
> That is very accessible to an IT manager who's not a database
> expert, and conceptually very clean.  It doesn't directly address
> what's innovative about it, though, nor does it directly address why
> it's valuable -- although one could infer both through a close
> reading.
> To extend that such that the innovative nature and benefits are more
> explicitly stated, perhaps:
> SSI allows you to enforce arbitrarily complex user-defined business
> rules within the database without blocking, by automatically
> detecting live race conditions in your SQL transactions at runtime.
> It protects you by safely rolling some of them back (which can be
> retried safely).
> It's more than two lines, but I'm not immediately able to see what
> to cut.
> By the way, I did some google searches to try to find a prior
> production quality implementation, and have so far not found any.  I
> have discovered that SSI is a very popular TLA, including its use
> for something called Server Side Includes (SSI.php) which is a
> popular enough technology with databases for people to be listing
> years of experience with it on their LinkedIn pages.  I don't know
> how much of a problem that might be.  I guess at a minimum we should
> add Serializable Snapshot Isolation to the Wikipedia SSI page:
> Maybe we shouldn't use SSI without spelling out Serializable
> Snapshot Isolation, to avoid confusion.
> -Kevin

Oleg Bartunov, Research Scientist, Head of AstroNet (,
Sternberg Astronomical Institute, Moscow University, Russia
Internet: oleg(at)sai(dot)msu(dot)su,
phone: +007(495)939-16-83, +007(495)939-23-83

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