Re: Article about supposed "murky" future for Oracle

"rkusenet" <rkusenet_at_sympatico.ca> wrote in message news:c4h9kp$2hc7c0$1_at_ID-75254.news.uni-berlin.de...
> "Thomas Kyte" <thomas.kyte_at_oracle.com> wrote
>
> > so your recent posting in another newsgroup trying to figure out why a
> > simple query in read committed isolation is deadlocking with other
> > statements was due to an improperly designed system?
>
> If you are referring to this post http://tinyurl.com/2rtx7 then this is
> the answer. The customer did not have the index at all. I was preplexed
> with the deadlock because I thought they had the necessary index. After
> all we control the schema by which the database was created at
> the customer site and was running fine for many months.
> Only when I looked at the schema at the customer site, I found the index
missing.
> Without the index, SQLServer resorted to table lock leading to deadlock.
Once
> the index was created, the problem went away for good, as it was in the
> past. The customer hasn't still given an answer on how the index
disappeared.

I think the problem for those of us from an Oracle bent is that in general we think of indexes as a performance enhancement tool, not as a way to avoid users being thrown out of their applications. The index contains absolutely no information that is not already available in the underlying object, and yet its absence can cause deadlock.

> Now please don't tell me that Oracle customers don't goof up. Recently I
read
> here how Orbitz DBAs deleted some important Oracle configuration files,
> which lead to that infamous crash in Aug 2003.

Of course customers goof up, I'm a little wary of the Orbitz incident since it seems to be acquiring urban legend status with different explanations as to what happened and why, but of course customers mess up.

> This problem was also solved. What is a good design differs from product
> to product. Oracle must be having its own quirks which other RDBMS may
> not find it bit odd. I don't understand what u are trying to prove?

If we are still talking about versioning/read consistency then I think the point is just that other databases require extra thought about how to obtain correct,consistent results that just don't need to be even considered in an Oracle environment. Yes, sensible app designers will consider the features and quirks of the database they are using - though there is a huge caveat in that most apps these days are database ignorant, sorry independent - but any time you can take considerations away from designers and just let the database handle it you score a big win.

-- 
Niall Litchfield
Oracle DBA
Audit Commission UK