Hello,

just one question about the AdventureWorksDB sample database: Why are there
"artificial" primary keys such as TimeKey and AccountKey which start from 1?
Is there any reason not to use the date, for example 1/1/2004, or the
specific account number, as primary key?
TimeKey FullDateAlternateKey DayNumberOfWeek
915 1/1/2004 5
916 1/2/2004 6
917 1/3/2004 7
918 1/4/2004 1


Thanks.

Mark

they use identify columns.
So the counter starts at 1.

in a standard DW system generally we use an integer instead of a date/time
for the time dimension for performance reason.
for other dimensions, using a surrogatekey give some advantages. Specially
if your source system use characters has a key. Also, surrogatekeys allow
you to load data from multiple sources where you'll have the same account
number, using surrogate keys you can create 2 keys (1 by source).
again, using integer improve performance and storage.

when you have only 1 source where the codes are integers and you don't have
slow changing dimensions, then you can use the source key instead of a
surrogate key.

remember the adv. works is a sample based on standard best practices for a
DW structure.

"Mark" <mfrohgast (AT) yahoo (DOT) de> wrote

Thank you!

Mark

"Jeje" <willgart (AT) hotmail (DOT) com> wrote