Re: Parallel Query Option on 7.3.4

Hi.

Using Parallel Querry on small tables foten do not help performance, it's on large table
it mostly will give you gain in performance.

Best regards

kgordin_at_my-dejanews.com wrote in article <7204fo$29n$1_at_nnrp1.dejanews.com>...
> In article <71qf03$a93$1_at_news.monmouth.com>,
> "Roman Gelfand" <rgelfand_at_masmid.com> wrote:
> > select /*+ PARALLEL(TBL1, 5) */ fld1, fld2, fld3, fld4 from tbl1 order
by
> > fld5, fld6;
> >
> > The table tbl1 contains 5000 rows. Can anyone tell me why I am not
seeing
> > performance improvement using parallel query option.
> >
> > Thanks for your help
> >
> >
>
> How many CPUs do you have? On how many disks is your data spread? Are
there
> enough parallel query servers running? Is there enough memory? If your
system
> has a memory or cpu bottleneck you will not see any gain by improving the
IO.
> If you have one CPU, improvemnts may be very small. If all the data you
are
> accessing is on the same drive it does not matter how many parallel
processes
> will read it. In fact, it can decrease the performance because instead of
> sequential read the system will do scattered reads with all the overhead
of
> seek operations. Besides, you do a sort, and that may take more time than
> actually reading the data from the disk.
>
> Too many possibilities ;)
>
> Cheers,
>
> Kirill
>
> -----------== Posted via Deja News, The Discussion Network ==----------
> http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
 

>
Received on Sun Nov 08 1998 - 10:22:25 CST