Re: Re[2]: Dirty reads

From: Igor Neyman <ineyman_at_perceptron.com>
Date: Wed, 4 Oct 2000 12:33:05 -0400
Message-Id: <10639.118487@fatcity.com>

MS SQL allows 'dirty reads', causing all kinds of problems with this 'feature' (?!) (I'd rather call it - 'bug').

Igor Neyman, OCP DBA
Perceptron, Inc.
(734)414-4627
ineyman_at_perceptron.com

Original Message ----- From: "Jim Conboy" <Jim.Conboy_at_trw.com> To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Wednesday, October 04, 2000 12:15 PM Subject: Re: Re[2]: Dirty reads

Am I the only one with no imagination? How is uncommitted data of any practical value? Of course I can see the desire to read data as up-to-date as possible, but if the possibility exists that the data read is 'wrong' I can't see any advantage to this, and loads of potential harm.

Jim

>>> dgoulet_at_vicr.com 10/04/00 11:06AM >>> The subject of "dirty reads" has been around for as long as I've worked with Oracle, which started back in 1985. It's basically a forbidden subject. I know
DB2 allows this and there are others who would like it since rollback segments
would become unnecessary from their point of view (it would also make some batch
processing a little more error free). But in looking at the ANSI SQL standard
book that I've got here, dirty reads are NOT standard behavior, actually it's
prohibited!!

Dick Goulet.

____________________Reply Separator____________________
Author: "Ron Rogers" <RROGERS_at_galottery.org>
Date:       10/3/00 1:11 PM

I don't think that Oracle would allow it because until the commit is issued the
other users see the "old" data and the user making the changes sees the new data. If the user wants to see both copies of the data have them login twice.
One to make the changes and the other to view the original data. To circumvent
Oracle's method of data integrity would destroy the foundation building blocks
of the database
ROR ª¿ª >>> turner_at_tellme.com 10/03/00 03:51PM >>> Is there any way to say I want a select that won't look at the rollback segment? The user doesn't care if it's a dirty read.

Dave Turner

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