RE: rules for database link usage
- From: "Matt" <mvshelton@xxxxxxxxxxxxx>
- To: <SUzzell@xxxxxxxxxx>, <curtisbl@xxxxxxxxx>, <backseatdba@xxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
- Date: Mon, 17 Feb 2014 11:13:25 -0500
I agree with the possible performance problem of views with database links.
I have encountered this situation multiple time and one possible solution is
the materialized view other times it's a tuning exercise. To decide on the
question do I create a view over a database link or a materialized really
depends on your requirements. For me I may do either based on the
requirements of the application such things as uptime, maintenance, and
performance .
If I do create a database link to a remote object I always use views with
private database links and put these objects in a separate schema to control
security.
Thanks, Matt
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Uzzell, Stephan
Sent: Monday, February 17, 2014 11:05 AM
To: 'curtisbl@xxxxxxxxx'; backseatdba@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx
Cc: Uzzell, Stephan
Subject: RE: rules for database link usage
Bobby,
Could you say a bit more about the view issue (or point me towards some
documentation)? One of the many fires we're fighting is a performance issue
where a DB link is involved. We have not yet directly implicated the DB Link
in the performance problem, but.
Thanks,
stephan
Stephan Uzzell
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Bobby Curtis
Sent: Monday, 17 February, 2014 10:56
To: backseatdba@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx
Subject: RE: rules for database link usage
Jeff,
This is a slippery slope. Database Links can be good; however, I've seen the
wrong use of them where they cause a problems. Example, if you query a view
on the remote side through a dblink, your wait times may go up because you
have wait for the view to compile and then return the result set. This
extends your connection and retrieval times.
If you have to use a database link, I would use materialized views on the
remote side to keep the data readily available. This way you are not
compiling on the fly and waiting for the result set to be returned.
Ideally, I try to keep the data as close as possible to where the execution
is going to happen.
Just my 2cents.
Bobby
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Jeff C
Sent: Monday, February 17, 2014 10:48 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: rules for database link usage
What are you rules for using database links in a production application? We
currently have an application that needs data from another database and I am
torn between having them just use a database link or copying the data to
their database using various methods.
I am leaning towards duplicating the data because I prefer to not have this
database dependent on the other or one causing havoc on the other. But I
guess if that didn't matter what in general are your rules?
Jeff
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