Subject:
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Re: BI Portal site re-launches!
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Newsgroups:
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lugnet.build
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Date:
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Tue, 9 Jul 2002 13:56:04 GMT
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Viewed:
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4533 times
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In lugnet.build, Jake McKee writes:
> In lugnet.build, Ross Crawford writes:
>
> > As Oliver says, de-normalising the database may be an effective way of
> > reducing the server load. Store the tree total against each category, and
> > update it when a link is submitted.
>
> Can you explain this a little more? I intrigued by the concept, and
> completely confused. My (limited) knowledge of databases tells me that
> normalizing the DB is a way to add efficiency. What I am missing in your
> suggestion?
Normalising makes things more space efficient (by reducing storage of
redundant information), denormalising makes things more efficient at runtime
(by reducing joins).
Storing the tree total against each category is an example of keeping
redundant data instead of calculating it on the fly (I forget if this is a
kind of denormalization or not and if it is I forget whether it's "first
normal form" or "second normal form" or what... I play a DBA at clients but
am not one, technically). Rather than doing a query to calculate the total
when you are asked to, you store the info and recalculate when you know the
value would have changed (when someone adds or removes something).
Other kinds of time/space tradeoffs include things like moving code table
values into the main rows.
Try this URL:
http://www.palslib.com/Fundamentals/Database_Design.html
particularly this article
http://www.dbpd.com/vault/9804date.htm
Note that fully normalized databases are the most compact and have no
redundant information (and thus have the highest data integrity) but also
are the slowest.
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Message has 1 Reply:
 | | Re: BI Portal site re-launches!
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| (...) The downside to denormalizing is you have to remember to update your data in several places whenever you update it. Depending on how complex you want to make your code it can be worth it to denormalize in some places to allow quicker searches. (...) (22 years ago, 9-Jul-02, to lugnet.build, lugnet.off-topic.geek)
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Message is in Reply To:
| | Re: BI Portal site re-launches!
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| (...) Can you explain this a little more? I intrigued by the concept, and completely confused. My (limited) knowledge of databases tells me that normalizing the DB is a way to add efficiency. What I am missing in your suggestion? (...) Well, the (...) (22 years ago, 9-Jul-02, to lugnet.build)
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