Re: degree of parallelism

A parallel degree of 3 doesn't mean there are only 3 processes involved ...

Example - PARALLEL(table, 3, 1)
if you give this hint with a query that is doing a sort operation you'll find that it's using 7 processes !
1 Query coordinatior
3 PQ slaves for querying
3 PQ slaves for sorting data coming from the first 3 query slaves

The last parameter in the parallel degree hint is the inter instance parallellism for parallel server (or rac) - you can execute 1 query over multiple instances in a clustered (OPS/RAC) environment .....

"dias" <ydias_at_hotmail.com> wrote in message news:55a68b47.0111230830.4c239d90_at_posting.google.com...
> desantis77_at_aol.com (DESANTIS77) wrote in message
news:<20011121132810.29621.00001101_at_mb-fv.aol.com>...
> > I am preparing for an oracle dba exam and I came across something in my
> > exam cram book that looked a little strange. If possible could you tell
me what
> > the degree of parallelism is for the following statement:
> >
> > insert /*+ PARALLEL(iarc,6) */ into invoice_archive iarc
> > select * from sales where invoice_no < 10000;
> >
> >
> > The book said that the degree of parallelism that is being requested is
3 but i
> > thought that it should be 6.
> >
> > Thanks
> >
> > Dominick
>
> Hi,
>
> The degee of parallelism can be reduced by the number of the parallel
> processes. If you have only 3 processes, the degree will be 3 and not
> 6.
>
> Dias
Received on Fri Nov 23 2001 - 12:11:59 CST