Re: How does Oracle support REPEATABLE READ

In article <3cc95e28.23674843_at_news.nl.uu.net>, benbrugman_at_onbekend.nl says...
>
>On 26 Apr 2002 06:29:59 -0700, Thomas Kyte <tkyte_at_oracle.com> wrote:
>>>Business rule is : ONE PING ONLY.
>>>(In the column B3 in table tB there is only one row allowed
>>>which contains the word PING).
>>>
>>
>>and anyone who doesn't use declaritive integrity constraints to implement this
>>business rule is not doing it the right way. Enforcing a unique constraint with
>>procedural code is not a very bright idea.
>
>The business rule was One Ping only, it didn't say anything about the
>column being unique. Secondly the example was only provided to show

k, concede that - misread the req. enter function based index.

create unique index on t( decode( b3, 'PING', b3, null ) );

that would do it.

>that there are transactions which sometimes can not be serialized.
> The question was "Show us these transactions and the results.", not
>give us an example which we can not solve in another way.
>
>Other database will give you deadlocks, I have no problem
>with that, deadlock detection takes care of that (in some databases).

and other databases (other then oracle) will not. The basic point, my bottom line (enough said on this, this is my last followup) is this:

databases differ FUNDEMENTALLY from eachother in concurrency controls. There are two camps with many products in each:

o those that lock
o those that do not

If you are going to develop "database independent" applications, you must be aware of this. Matters not how many papers you read, this is the way that it works -- for better or worse. It is simply a matter of that (in real life)

....

>ben brugman
>Ben Brugman

--
Thomas Kyte (tkyte@oracle.com)             http://asktom.oracle.com/ 
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