Just like it takes thousands of years for a photon to make it from the Sun's
core to the surface...ah physics, so fun!
-----Original Message-----
From: Jonathan Lewis <jonathan@xxxxxxxxxxxxxxxxxx>
Sent: Friday, January 10, 2020 11:19 AM
To: Oracle L <oracle-l@xxxxxxxxxxxxx>
Subject: Re: Using dblinks over distance
I'm not going to argue about the latency/bandwidth thing, but I have to say
that one of the things I learned in physics classes about 50 years ago was that
when you caused an electric current to flow the "flow" was virtually
instantaneous but if you were running the current through a cable across the
Atlantic it would take about 100 years for any individual electron to get from
one side to the other. (Just like a Bugatti Veyron won't be able to get round
the M26 (London Orbital) in 26 minutes at 5:00 pm on Friday afternoon - only
more so)
Regards
Jonathan Lewis
________________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx <oracle-l-bounce@xxxxxxxxxxxxx> on behalf
of Clay Jackson (cjackson) <Clay.Jackson@xxxxxxxxx>
Sent: 10 January 2020 16:07
To: knecht.stefan@xxxxxxxxx; vishal@xxxxxxxxxxxxxxx
Cc: Mladen Gogala; oracle-l-freelists
Subject: RE: Using dblinks over distance
Let's not confuse latency (how long it takes one electron to get from one end
of the pipe to the other, usually expressed in some fraction or multiple of
seconds) with bandwidth (how many "thingies" can I move from one end of the
pipe to the other in some period of time, usually expressed in bits per
second).
Both contribute to making a network (any network, not just local or wide-area)
APPEAR either fast or slow. The latter (bandwidth) is something that is
almost completely controllable (just add money). The former (latency) is
usually a VERY small component of the overall "business application response
time", since light moves at 300 MILLION meters per second (and electrons only a
bit slower). But, as the saying goes, "The speed of light isn't just a good
idea, it's THE LAW"; so, in any network involving connection spanning 10K KM or
more, latency will be a larger component..
I think there have already been a few suggestions on how to mitigate latency
(like local materialized views) and, as I said, bandwidth is just a question of
"How big is your checkbook?".
Clay Jackson
Database Solutions Sales Engineer
clay.jackson@xxxxxxxxx<mailto:clay.jackson@xxxxxxxxx>
office 949-754-1203 mobile 425-802-9603 [cid:image003.png@01D5C78D.0E0962F0]
From: oracle-l-bounce@xxxxxxxxxxxxx <oracle-l-bounce@xxxxxxxxxxxxx> On Behalf
Of Stefan Knecht
Sent: Thursday, January 9, 2020 11:42 PM
To: vishal@xxxxxxxxxxxxxxx
Cc: Mladen Gogala <gogala.mladen@xxxxxxxxx>; oracle-l-freelists
<oracle-l@xxxxxxxxxxxxx>
Subject: Re: Using dblinks over distance
CAUTION: This email originated from outside of the organization. Do not follow
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Not really. If you are going over the internet, regardless of your connection
speed, you will hit bottlenecks due to the competition will millions of others
(across a 1000 miles).
What Mladen is referring to is purchasing dedicated bandwith between the 2
locations, and thus, getting far more guaranteed speeds and latency.
On Fri, 10 Jan 2020, 02:40 Vishal Gupta,
<vishal@xxxxxxxxxxxxxxx<mailto:vishal@xxxxxxxxxxxxxxx>> wrote:
Problem of slow response over database link to a database situation at 1000+
miles distance is indeed distance (i.e. network latency), not speed.
Regards,
Vishal Gupta
From: <oracle-l-bounce@xxxxxxxxxxxxx<mailto:oracle-l-bounce@xxxxxxxxxxxxx>> on
behalf of Mladen Gogala
<gogala.mladen@xxxxxxxxx<mailto:gogala.mladen@xxxxxxxxx>>
Reply-To: <gogala.mladen@xxxxxxxxx<mailto:gogala.mladen@xxxxxxxxx>>
Date: Thursday, 9 January 2020 at 18:41
To: <oracle-l@xxxxxxxxxxxxx<mailto:oracle-l@xxxxxxxxxxxxx>>
Subject: Re: Using dblinks over distance
The problem is not the distance, the problem is the network speed. WAN is
usually slightly slower than 10Gb LAN. Thus the solution: improve the network
speed. Buy more dedicated lines from your network provider. Also, it's about
the application design: you shouldn't do real time queries against the database
in the server room far, far away. You should use materialized views and cache
the data locally. It's called "intelligent design".
On 1/9/20 1:27 PM, Cohen, Andrew M. wrote:
As we move some of our database VMs to the cloud we have come across the
following situation where the database links between databases (which used to
be all on prem) are now being attempted over thousands of miles. This has
caused extremely poor performance. We have found that an arraysize session
parameter assists with some of the select statements, but updates which use
links to get data don't seem to perform any better with this arraysize
parameter. To make matters more complicated, we are making these calls in
PeopleSoft applications.
We're using Oracle 18 and 19 databases on Rhel 7 mostly.
Does anyone have any suggestions as to how to improve performance using
database links over distance?
Thanks,
Andy
--
Mladen Gogala
Database Consultant
Tel: (347) 321-1217
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