Re: Another exception (Transaction level)

From: Dmitry Tkach <dmitry(at)openratings(dot)com>
To: Fernando Nasser <fnasser(at)redhat(dot)com>
Cc: Ole Streicher <ole-usenet-08(at)gmx(dot)net>, pgsql-jdbc(at)postgresql(dot)org, Paul Thomas <paul(at)tmsl(dot)demon(dot)co(dot)uk>
Subject: Re: Another exception (Transaction level)
Date: 2003-07-28 15:38:45
Message-ID: 3F254385.1090903@openratings.com
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>
> If it disagrees it is not with me, but with the committee who wrote
> the SQL standard.

... or with your reading of the standard perhaps? :-)

> But I don't think it disagrees that much (see below).
>
>
>> "PostgreSQL does not provide the isolation levels READ UNCOMMITTED
>> and REPEATABLE READ. "
>>
>
> It can't provide REPEATABLE READ. It could/should make it a synonym
> for SERIALIZABLE.

Maybe. But it doesn't, does it?
At least, at the moment, there is no such thing as 'REPEATABLE READ' in
postgres at all, so any argument that it is "supported" doesn't seem to
make much sense...
Perhaps, you meant to say "it could/should be supported"?... :-)

>
> And SERIALIZABLE, which is a misnomer, in PostgreSQL does not actually
> "serialize" anything, although it does provide the required level of
> isolation required in the standard, I believe.

It makes concurrent transactions behave as if they were serialized.
That's exactly what serializable means....

>
> It is unsupported because they give you syntax errors. Perhaps people
> preferred not to use the allowances in the standard because it could
> confuse people as not all users know enough SQL to understand that.

Yeah... I have never met a user who would understand that actually :-)

> If you don't want to look at the standard then look at Date's book.

To the contrary, I'd *love to* look at it. I just don't know *where*.
If you could give me a link, that would be great.
or, at least, if you just qoute a relevant section you are referring
to... that would at least give me the context ...

>
> And, again, I only _read_ the standard, I did not wrote it. Please
> send your complains to the SQL committee.

I don't have any complaints. I just find it hard to believe that it is
really meant to be the way you read it.
I mean, maybe it is. But, unless I can see it with my own eyes, I still
find it a lot more likely that you've just misread what it is saying...

Dima

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