RE: two instance -- one database
- From: "Mercadante, Thomas F (LABOR)" <Thomas.Mercadante@xxxxxxxxxxxxxxxxx>
- To: "John Kanagaraj" <john.kanagaraj@xxxxxxxxx>, <Mark.Brady@xxxxxxxxxxxxxxxxx>, "oracle-l" <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 25 Sep 2008 08:32:23 -0400
John,
That's why I asked him to test it to see if it was an issue. It used to
be an issue but I was unsure if it was resolved or not.
As always, I suggested testing testing testing.
Tom
-----Original Message-----
From: John Kanagaraj [mailto:john.kanagaraj@xxxxxxxxx]
Sent: Wednesday, September 24, 2008 9:34 PM
To: Mercadante, Thomas F (LABOR); Mark.Brady@xxxxxxxxxxxxxxxxx; oracle-l
Subject: Re: two instance -- one database
Tom,
Imho, generally, pushing filter predicates over dblink does occur in
newer versions (>8i) as long as you don't have local tables involved
(as in this case).
John
On 9/24/08, Mercadante, Thomas F (LABOR)
<Thomas.Mercadante@xxxxxxxxxxxxxxxxx> wrote:
> Mark,
>
>
>
> 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.
>
>
> Tom
>
>
>
> ________________________________
>
> 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?
> Anything?
>
>
>
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