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Re: Article about supposed "murky" future for Oracle

From: Daniel Morgan <>
Date: Tue, 30 Mar 2004 15:32:30 -0800
Message-ID: <1080689533.255946@yasure>

Serge Rielau wrote:

> Daniel Morgan wrote:

>>> Instead of SCROLL CURSOR, a TEMP TABLE can also be created for same.
>> And what happens during the time the temp table is being loaded?
>> Same thing that happens in SQL Server. Surely you are not advocating
>> a full table lock for as long as it takes to load a temp table.

> There is no such thing as a free lunch. The versioning comes at a cost
> too. Pushing a version and managing the rollback segments is not for free.

Of course not. But please also acknowledge that even with that overhead the following is still possible:

> You can look at it from another angle:
> If I need to look at a row and it is currently being updated. How do I
> gamble? If I presume the update will commit then looking at old data
> will result in a decision being made on stale data. That can be bad.

Depends on whether the architecture is such that you have minimized the possibility of multiple transactions attempting to update the same row at essentially the same time. We all design to maximize our strengths and to minimize our weaknesses: Or at least we should.

> On the flip side, I can read uncommited data in most RDBMS and go wrong
> when the transaction on which's success I depend rolls back.
> I wouldn't want to state one isolation level is better than the other.

Unless you were trying to build other infrastructure on top of it such as that contained in DBMS_FLASHBACK and other things that Oracle has built on top of their concurrency model that so far are not found in any other commercial RDBMS. One should note that a huge investment is taking place at Microsoft to duplicate Oracle's model with Yukon. As it is not being done for marketing purposes it is reasonable to assume it is so that they can recreate some of the same functionality.

> AFAIK e.g. Informix has a "skip uncommitted" mode where it conveniently
> ignores rows that are in limbo. Dangerous? Yeah. But writers don't block
> readers and it surely is good enough to find free seats on an airplane :-)
> Cheers
> Serge
> PS: I always thought WallStreet was/is a Sybase Stronghold obviously
> Banks could live with what Sybase has to offer.

Live with or prosper with are of course two different things. There are plenty of people living with Siebel and some of the other commercial packages.

Daniel Morgan
(replace 'x' with a 'u' to reply)
Received on Tue Mar 30 2004 - 17:32:30 CST

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