[Year 12 IPM] Redundancy

[Joel Walton]

While mirroring data is technically DR I dont think
that you would classify
it that way :)

>From my experience DR is more inline with Allan's
example

1. Putting in 'data' in the database that is really
calculated 'information'
Eg hourly_rate * hours_worked
2. The same fields of information in the database with
the exactly the same
information
        That information should be normalised so it is
only in one place.
        As you risk obsolete/inaccurate data in your
system if you have it
in multiple fields of the same data.

Just a quick thought.

Cheers,

Joel Walton
Shepparton High School


----- Original Message ----- 
From: "Mark Kelly" <kel at mckinnonsc.vic.edu.au>
To: "Year 12 Information Technology Processing and
Management
Teachers'Mailing List" <ipm at edulists.com.au>
Sent: Wednesday, October 12, 2005 1:29 PM
Subject: Re: [Year 12 IPM] Redundancy


> Data redundancy (DR) can be good and bad.
>
> When bad, it wastes storage space or blows out the
size of a data
> structure with no benefit (e.g. as previously
mentioned, the same data
> stored in 2 tables in a database).  I suppose DR can
even mean the same
> data stored in multiple copies of the same file. 
Database normalization
> can help fix DR.
>
> On the positive side, DR can be good.  Backups are
classic examples of
> DR.  Backup servers or backup data hosts which take
over in case the
> primary host fails) are DR.  RAID's mirroring is DR.
>
> Dunno if that helps anyone  :-o
>
> Andrew Sutton wrote:
> > Doesn't it also have to do with two fields in the
one table that are
> > essentially giving you the same information? For
example, In a table,
You
> > shouldn't need the Age field if you have an
accurate D.O.B. field.
> >
> > -----Original Message-----
> > From: ipm-bounces at edulists.com.au
[mailto:ipm-bounces at edulists.com.au]
On
> > Behalf Of Geraldine McKenna
> > Sent: Tuesday, 11 October 2005 11:41 PM
> > To: Year 12 Information Technology Processing and
Management
> > Teachers'MailingList
> > Subject: [Year 12 IPM] Redundancy
> >
> > Hi everyone,
> > Thanks for the help this list has provided
throughout the year again!!
Could
> > someone plese explain to me the meaning of 'data
redundancy'? My
> > understanding is that it relates to loss of data
and I also think it is
> > different to 'data integrity' but am not clear
about these. It has come
up
> > as a result of students having just completed the
Insight Trial Exam
paper.
> > Thanks in advance.
> > Geraldine McKenna
> > IT Coordinator
> > Avila College
> > Mt Waverley
> >
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> -- 
> Mark Kelly
> Manager - Information Systems
> McKinnon Secondary College
> McKinnon Rd McKinnon 3204, Victoria Australia
> Phone +613 95780844  Fax +613 95789253
> http://www.mckinnonsc.vic.edu.au
> IPM Lecture notes: http://vceit.com
> Moderator: IPM Mailing List
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