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Tuesday, 8 September 2009
By Steve Schnepp on Tuesday, 8 September 2009, 22:00
Doing a case insensitive search is a very common
task, but is quite hard to optimize correctly. But
since it's done via a UPPER(MY_COLUMN) = UPPER('MY_DATA'), it
doesn't use the index that could be on MY_COLUMN.
Different RDMS means different approaches.
Friday, 31 July 2009
By Steve Schnepp on Friday, 31 July 2009, 08:00
Constraints are considered a Good Thing
. They enable to rely more
heavily on the validity of the database. It is quite important to note that
validity is in terms of modeling and not in terms of
business [1].
The biggest complains we can have about constraints is that it is sometimes quite annoying to do some updates while consistently validating the constraints. You have to care about the order of the operations you do.
[1] I'll write an article about this later
Tuesday, 2 June 2009
By Steve Schnepp on Tuesday, 2 June 2009, 08:00
Everyone is unanimous that database normalization is considered a Good Thing.
But it usually comes with a cost : writing queries can be very tedious since you always have to join many tables together to be able to retrieve useful human data from all those reference tables.
Tuesday, 19 May 2009
By Steve Schnepp on Tuesday, 19 May 2009, 08:00
When you just decided to use Surrogate Keys, another problem arises : which value should I use ? It seems to be a very simple problem since the key now is completely in isolation in your application and is not related to any data. The choice is quite bonding, since a change means that every value has to be changed, and you did not let this key leak outside the database did you ?
The keypoint here is isolation. Many differents kinds of isolation are available, and soon you will be able to make a informed decision.
Friday, 17 April 2009
By Steve Schnepp on Friday, 17 April 2009, 17:05
In huge tables, usually only a fraction of the table is used on a regular basis. The rest is useful either for historical purpose, or is just not being treated right now.
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