RE: two instance -- one database

  • From: "Mercadante, Thomas F (LABOR)" <Thomas.Mercadante@xxxxxxxxxxxxxxxxx>
  • To: <Mark.Brady@xxxxxxxxxxxxxxxxx>, "oracle-l" <oracle-l@xxxxxxxxxxxxx>
  • Date: Wed, 24 Sep 2008 13:01:24 -0400



Have you tested a multi-table join across the database link?  

Pick two very large tables.  

Create a query and run it on the source database with timing turned on.

Run the same query on the remote database and compare the timings.


This used to be a very big issue.  The "where" clause used to be
executed locally which means that all data from both tables was brought
across the database link and joined locally.  A very bad arrangement.


I agree with Tim Gorman.  It accomplishes nothing and adds complexity at
your personal cost.  You will be tuning this arrangement forever.




From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Brady, Mark
Sent: Wednesday, September 24, 2008 11:07 AM
To: oracle-l
Subject: two instance -- one database


I have a friend (no really, this isn't some lame way of telling you
about me but trying to hide that by ... )



I have a friend, and at his company they have an Oracle database with
tables and data. We'll call it Database A and they have another Database
B that has views across dblinks to each of the tables in Database A. The
data team says that this protects Database A from bad queries.


So can anyone think of any possible benefit from this arrangement? Will
administration be easier, queries faster, performance more predictable?


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