Re: unable to see new/updated records

From: Mladen Gogala <no_at_email.here.invalid>
Date: Wed, 2 Dec 2009 15:59:17 +0000 (UTC)
Message-ID: <pan.2009.12.02.15.59.15_at_email.here.invalid>

On Wed, 02 Dec 2009 09:25:39 +0100, GD wrote:

> Mladen Gogala wrote:

>> On Tue, 01 Dec 2009 22:25:09 +0100, GD wrote:
>> 
>> 
>>> That's the law only for serializable transactions, not for "normal"
>>> transactions.
>> 
>> Nope. In Oracle RDBMS, transaction can see only the data that was
>> committed at the time  when the transaction was started. That is always
>> the case. Serializable prevents phantom reads by imposing a shared lock

>
>
> This is not true. Please perform a simple test or consult your Concepts
> manual:
>
> http://download.oracle.com/docs/cd/B19306_01/server.102/b14220/
consist.htm#CNCPT621
>
> "Read committed
> This is the default transaction isolation level. Each query executed by
> a transaction sees only data that was committed before the query (not
> the transaction) began. An Oracle query never reads dirty (uncommitted)
> data. Because Oracle does not prevent other transactions from modifying
> the data read by a query, that data can be changed by other transactions
> between two executions of the query. Thus, a transaction that runs a
> given query twice can experience both nonrepeatable read and phantoms."
>
> Regards

You are right. I was fully convinced that it was consistent up to the point that transaction has started. I humbly apologize.

-- 
http://mgogala.byethost5.com

Received on Wed Dec 02 2009 - 09:59:17 CST