Re: Database Link Question (For Guru)!

If you really want to force the query to be executed on a certain system, then you may want to use the DRIVING_SITE hint. The Oracle docs on distributed database queries does a really good job of explaining how distributed queries work.

HTH,
Brian

Barbara Kennedy wrote:
>
> It depends upon the query. If you join table 1 in Db1 with table2 in db2
> then you will do a full table scan in db2 and bring all the data over to db1
> to do the join. So you would have a lot of IO hits. If from DB1 you just
> query a table or tables that are in db2 then it will be as if you were
> running it from a client application.
> Jim
> <japs1_at_my-deja.com> wrote in message news:8nqtmk$rs7$1_at_nnrp1.deja.com...
> > I am considering creating a database link between two production
> > databases (Db1 and Db2).
> >
> > The link will allow Db1 to interrogate certain tables on Db2.
> >
> > Both Db1 and Db2 reside on different servers running Oracle 7.3 on Unix.
> >
> > The question I have is, where does the loading occur when a query is
> > executed from Db1 on Db2.
> >
> > Both Db1 and Db2 are supporting business critical applications, and
> > this is where my concerns lie.
> >
> > I am keen to understand the impact on both databases and both servers
> > if a query (or multiple simultaneous queries) are run from Db1 on Db2.
> >
> > Will there be an impact on the Db2 database if queries are run on it
> > from Db1?
> >
> > What processor takes the biggest hit. Is it server1 or server2, or do
> > both servers processors get used?
> >
> > Are Unix processes kicked off on both servers if a query is executed
> > from Db1 on Db2?
> >
> > Finally, I would appreciate if anyone could advise me of any other
> > drawbacks to creating a database link between two production databases.
> >
> > Eternal thanks in advance for any help,
> >
> > Japs1.
> >
> >
> > Sent via Deja.com http://www.deja.com/
> > Before you buy.
 

-- 
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Brian Peasland
Raytheons Systems at
  USGS EROS Data Center
These opinions are my own and do not
necessarily reflect the opinions of my 
company!
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