Hi !
I have came to the conclusion that I need a "Data Warehouse" ; I have
read some papers, and still have a few questions on the subject :
- Suppose I have a 'Sales' "fact table"... some Sales are "basic
sales", but some are more complicated, hence I need to store more
"attributes".
Do I create a new 'Special Sales' "fact table" ? Or is it better that
'Sales' table holds all the possible attributes, and have them "NULL"
when not relevant ? And what about using the "supertype" pattern ( a
special sale is described by a record in 'Sales' table and a record in
'Special Sales' that provides the additional attributes ) ?
([ this question relates to one of my previous posts -- and I thank
people who took time to answer me --, but I would like people's
opinion in the context of a data warehouse, that will contain up to
200 million records ! ])
- In a 'Time' dimension, each day, with its week, month, year, etc
must be entered in the corresponding table. Who does this process ? Is
it done automatically by some kind of mechanism in the RDMS or must it
be done manually ?
- Does data REALLY need to be denormalised (I am a newbie !) ? Is it
necessary or is it just a hacker optimisation ? I have allways been
taught to normalise !
- Do you know of any good web sites on the subject of designing a
Data Warehouse ?
Thanks in Advance for your answers !!
SerGioGio
Received on Tue Jun 04 2002 - 08:36:37 CDT
