Re: Locks rows

"Howard J. Rogers" <howardjr2000_at_yahoo.com.au> wrote in news:AzXW9.28933$jM5.74796_at_newsfeeds.bigpond.com:

> No problem. What you do is uninstall Oracle completely. And then you
> replace it with a product called SQL Server.
>
> SQL Server is well-known for the way somebody doing an update to a row
> causes all other people who are hoping to select from that table to
> grind to a halt.
>
> Incidentally, I'm not joking when I say this

The only time select's 'grind to a halt' is when the coder locked the row and put in the transaction a prompt: "how's the weather?"

> But in Oracle, we NEVER do this. Readers don't block writers, and
> writers don't block readers. And readers most certainly never block
> other readers!! And there is NO way around that. You can do a select
> which prevents anyone else from modifying a record (called a
> 'select...for update'), but that won't stop me *selecting* that
> record. In Oracle, selects never take locks (except for the special
> case of a 'for update' one) and so they can't themselves be in
> competition for a lock taken by someone else updating -and hence a
> select can never be 'locked out'.

To implement what Francky may need though, he may need to always use "select ... for update" so that in his situation (some serialized activity) he blocks until the row is completed. Correct?

-- 
Pablo Sanchez, High-Performance Database Engineering
http://www.hpdbe.com