March 12, 2009 at 4:20 am
i need the list of disadvatages of denormalization
March 13, 2009 at 4:20 am
I can already give you an obvious one :
if you need to modify a common piece of information, which is - in a normalized database design - hold in a single place, and in a denormalized design repeated accross all the records sharing that information, then you will have to perform an update on a possibly very large number of rows instead of on only one.
March 15, 2009 at 4:24 pm
Another key advantage of normalised databases is that they can easily enforce referential integrity.
(e.g. A 'class' must have one 'teacher').
These constraints can be harder to enforce in a denormalised design - leading to subtle bugs.
If you give us some context, we may be able to be more helpful...
March 16, 2009 at 10:10 pm
A quick internet search returned a whole bunch of results:
http://www.lcard.ru/~nail/sybase/perf/1088.htm
http://manuals.sybase.com/onlinebooks/group-as/asg1250e/ptallbk/@Generic__BookTextView/8455
http://bytes.com/topic/sql-server/answers/637874-denormalized-database-inquiry
Basically, repeated data and referential integrity (mentioned above) are the main reasons.
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