Re: Parallel processing advantages

That actually sounds like a really good way to saturate the disk with read requests, which will slow each user to a crawl.

If you can't fix the storage issue, about the only thing you can do is CACHE the table, so that Oracle can satisfy reads from the buffer cache rather than the disk. However, doing so can then saturate your buffer cache with the blocks from the table forcing out other high-use blocks.

I would stay away from PQ in your situation.

-Kevin

"Scott Watson" <swatson_at_datachest.com> wrote in message news:pojB6.642289$JT5.17477940_at_news20.bellglobal.com...
> I would like to know if there is any advantage to using parallel
 processing
> in the following situation. Now before you tell me that it would be
 better
> to stripe the table across disks and the like I realize that, however, I
> wanted to know if there was any advantage without changing the table
> whatsoever.
>
> Situation.
> 1 table 10,000,000 rows.
> Stored in one tablespace with all datafiles on the same disk.
> Access is read only
>
> Is there any performace increase when scanning a table that is on the same
> disk in parallel or is it better to scan it serially.
>
> My thinking would be as follows. If there was only one user accessing the
> table, and the table was the only object stored on the disk in question
 then
> parallel processing would not be faster. However, assuming that this is
 not
> the only object on disk and that multiple user may be using the table at
 any
> given time then wouldn't PQ be better as n slaves would be able to read
> n*mulit block read count bytes on each read. Therefore getting through
 the
> table quicker all the while services other request from the same disk.
>
> Thanks for your input.
> Scott Watson.
>
>
>
Received on Thu Apr 12 2001 - 12:39:39 CDT