RE: database links and performance

  • From: "Knight, Jon" <jknight@xxxxxxxxxxxxxx>
  • To: "'thomas.mercadante@xxxxxxxxxxxxxxxxx'" <thomas.mercadante@xxxxxxxxxxxxxxxxx>, "'jdunn@xxxxxxxxx'" <jdunn@xxxxxxxxx>, Oracle-L@xxxxxxxxxxxxx
  • Date: Tue, 8 Feb 2005 09:42:45 -0600

  I can second Tom's comment that "bad things happen" when joining across
links.  Especially if the remote tables have much size.  Other strategies
are create a function on the remote DB to return just a small result set
across the link (if applicable.)  Replicate certain data to your local DB
depending on needs/space.
  We have also observed a performance hit (significant in some cases) even
when both DBs are on the the same box.  That said, links are a great thing.
We use them all the time.

Jon Knight
Senior Database Analyst
2525 Horizon Lake Drive, Suite 120
Memphis, TN  38133
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 -----Original Message-----
From:   oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Mercadante, Thomas F
Sent:   Tuesday, February 08, 2005 8:49 AM
To:     'jdunn@xxxxxxxxx'; Oracle-L@xxxxxxxxxxxxx
Subject:        RE: database links and performance


I use them in a couple of applications and generally, they work fine.  A
slow network is a slow network.  Yes, it can hurt performance.  If you think
that your network cannot support your application, then find another way to
do it.

A couple of tricks to consider:

If you need to join tables in the remote computer, consider creating a view
in that computer and calling that view from your local machine.  It will
perform much better - basically, limit the joins from remote tables - bad
things happen.

Good Luck.


-----Original Message-----
From: John Dunn [mailto:jdunn@xxxxxxxxx] 
Sent: Tuesday, February 08, 2005 9:40 AM
To: Oracle-L@xxxxxxxxxxxxx
Subject: database links and performance

We are considering using database links in Oracle 9i but are concerned about

Presumably the network can be a bottleneck when using database links.

Does anyone have any useful experiences with performance of database links?


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