[AccessD] Database Patent

To answer your 'shadow' database question, it depends on how the
developer wants to set things up.  There are lots of methods.  The
'test' database with the new design could be a snapshot of the data, so
that it is identical at the start, but the live and the test are then
separate.  In this case, the 'data dump' process is tested and approved,
and when the new system is ready, a final data dump is run (may take
more then a few minutes depending on the size of the system and speed of
the components).  We did this recently with our production/manufacturing
database.  Old system on a Unix box, new system on a windows based
platform.  Same software (just different versions (years apart).  The
final data dump, when we were ready to go live, took about 2 hours.
(Probably about 50 gigs of data).

You could also design a system that runs both at the same time.  In a
server based OS, triggers could be put in place that would update the
'shadow' server data.   

Another method would be to create an 'update' script.  Where the shadow
system is a mirror of the live site, and the done to it is a script that
updates the design (modifying data formats as needed), and the final
result is when that script is run against the live system.

Another method is partial jumpers.  Running the new data in a new
database and keeping the old data (and format) live in the old system,
until you are ready to put the whole new system in place.  I did this
with the ISFE (a system I built years ago, and recently updated).  The
new ISFE had only a handful of tables that the old system used.  So the
new database actually linked those tables while the new system went out.
The old system worked, with a few processes stuck with old data,
(processes unnecessary in the new system).  There were several things
that used the old system, however, but they used the linked tables.  So
while they were still entering data into the old database, the new
database saw all that data, because it was using the links.  When I was
ready to drop the old database, it was a simple matter of importing the
linked tables, took a minute, tops.

Drew

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Rocky Smolin
at Beach Access Software
Sent: Thursday, September 06, 2007 11:18 PM
To: 'Access Developers discussion and problem solving'
Cc: 'Jack Stone'
Subject: Re: [AccessD] Database Patent

Shamil:

Thanks for your response.  So you see nothing  unique in this patent?
(BTW,
the patent is not pending, but has been granted.) Does this look like
"old"
technology to you?  Is it obsolete technology based on what you describe
below as the current methods of implementing changes in the datamodel?

Just out of curiosity - So during the time that the new datamodel is
being
tested in the "shadow" database, am I correct in assuming that the
real-time
changes that are going on in the production database are also happening
in
the "shadow" database?  That it's a mirror?

Rocky

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