| Denormalized columns [message #208895] |
Tue, 12 December 2006 08:08  |
gajini
Messages: 262
Registered: January 2006
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Senior Member |
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Hi,
what is meant by denormalized columns?
When it's required/when we'll create it & how the values for these columns are obtained?
Can anyone explain this concept with an example?
Thanks,
Gajini
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| Re: Denormalized columns [message #208930 is a reply to message #208895] |
Tue, 12 December 2006 11:21  |
dba_blr
Messages: 43
Registered: December 2006
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Member |
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Denormalized columns are used mostly in DWH environments. To be more specific the Fact tables are mostly denormalized ones.
It helps in reducing resource contention.
These are generally populated using ETL process.
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| Re: Denormalized columns [message #208969 is a reply to message #208930] |
Tue, 12 December 2006 15:26 |
andrew again
Messages: 2577
Registered: March 2000
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Senior Member |
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http://www.dmreview.com/article_sub.cfm?articleID=5337
You should have a complete understanding of the real benefits and real disadvantages of denormalized structures before using them. You can denormalize from a parent table onto a child table (say to record a State on an address table), from the current table onto itself (e.g. price + tax = total) or from a child table onto a parent table (e.g. order table has a Total column based on child records).
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