Re: Changing isolation level?

Hemant Shah wrote:

> Folks,
>
> I have been working with DB2 for few years now, and in DB2 I can use the
> isolation level of CS. If one process has updated the row or deleted the row
> but not yet commited it, and another process tries to read it, it will be
> blocked until the first process commits the changes.
>
> In Oracle the default behaviour is that the select of the second process
> gets the old version of the data. How can I change the isolation level,
> preferably at database level, so that is blocks the selects if the select
> for update and delete has not yet commited the changes.
>
> Which isolation level in Oracle can I use?

You can't. Even if the write intentionally locks a record in Oracle writes do not block reads and reads do not block writes. I would suggest you pick up a copy of Tom Kyte's book "Expert one-on-one Oracle" and read the first three chapters. Put special attention into what he writes about the multiersion consistency model.

-- 
Daniel Morgan
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