Re: Why Oracle does not allow rollback of DDL statements?

On Nov 9, 3:36 pm, zigzag..._at_yahoo.com wrote:
> I have always been surprised why Oracle does a implicit commit when
> DDL statements (e.g create table …) are executed.  DDL statements
> simply write information (insert, delete and update) to data
> dictionary, so why DDL statement cannot be rolled back. Am I missing
> some thing?
>
> I was learning SQL Server few months ago and I noticed that SQL Server
> does allow rollback of DDL statements if I am not mistaken. It lloks
> like there is something in Oracle architecture which prevents rollback
> of DDL satements. Rollback of all staements should be allowed not just
> of DML statements.
>
> Appercaite your insight.

Actually, Oracle does 2 commits, one each before and after the DDL.

Part of why Oracle is different than other DBMS engines is its architecture - this is well explained in the book hpuxrac suggested.

I don't know the real reason you can't rollback DDL, but I suspect part of it is simply the evolution of the code. By now, it would be difficult. And there are workarounds in the modern versions.

As far as Serge's assertion that customers want to be able to change dicks in the middle of a screw, I mean, change defs in the middle of a view, that's as silly as some other things customers "want," like dirty reads. There may even be a legitimate requirement, but that's no reason to make it easy at the expense of other, more reasonable and ordinary things. I wonder how such things don't violate Codd's Physical Data Independence rule - they logically impair applications.

Just because there is a Codd rule that states the same language must be used to access the online catalog doesn't mean all possilbe language features need to apply to the catalog.

If you are going to see how sausage is made, bring along a barf bag.

jg

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