Re: Oracle with multiple CPUs

In article <8pjck2$4qh$1_at_nnrp1.deja.com>,   gdas_at_my-deja.com wrote:
> Hi, I apologize if these questions seem basic...

Nothing about this topic is basic. Parallel processing issues are usually considered to be advanced.

>
> We currently have an Oracle test/development database running on a
> single processor Windows NT Server. We have a new machine coming soon
> which is a dual processor NT box, but is expandable to up to 4 CPUs.
 I
> am hoping to move the database to this new machine and I am trying to
> assess what I will need to do in order for oracle to take advantage of
> the additional processor. I have 3 specific questions:
>
> 1. Will I need to change/set any of the init.ora parameters?

You will need to be sure you are running the enterprise addition of Oracle for the release you are installing. There is a parallel option you must install as well, I believe.

> 2. Currently none of my tables were created using any specified
 degree
> of parallelism. If I migrate the data to the new instance as is
> (without any degree of parallelism) and don't change the application
> code at all to send parallel hints, will I still see some benefit from
> the additional processor?

Here are some ways you may see benefits. You can do the following in SQL*Plus:

alter session enable parallel dml;

Assuming you are doing a full table scan against a fairly large table in your query, and you can set that table to parallel (degree 2), and your second processor can be dedicated to database processing, you could see a performance gain and not have to change any application SQL by providing hints.

> 3. Can I use parallel hints in SQL, even if the underlying tables
 were
> not created with any parallel clause?

The hints override the parallelism values set at the table level.

Be careful, however. I've seen situations where specifying parallel actually slows down performance. A good resource on the subject is the O'Rielly book: "Oracle Parallel Processing". I recommend it!

>

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Before you buy. Received on Tue Sep 12 2000 - 09:41:12 CDT