RE: Warehouse design: snowflake vs star schemas

Dennis,

Thanks for the link. It's a great DW resource. There are not only fundamentals, but some valuable real-life stuff, which is what I need. Live and learn, learn,learn...

Regards,
Alex

-----Original Message-----
WILLIAMS
Sent: Tuesday, October 08, 2002 7:39 PM
To: Multiple recipients of list ORACLE-L

Alexandre

   Stephane gave you an excellent reply. If you want to learn more about these DW design issues, I would start by visiting http://www.ralphkimball.com. He is one of the leading figures in the DW field, and has copies of all his articles posted on his site. I would start with the oldest articles because those are where he discusses the fundamentals of data warehousing.

Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----
Sent: Tuesday, October 08, 2002 3:29 AM
To: Multiple recipients of list ORACLE-L

Stéphane,

Thanks for response.

> I have always discplined myself to use star schema and
> never snowflake.

Would you mind asking why?

> The "Which one is easier to implement and easier ETL
> ?" is not a good question as your data model should
> not be design for the ETL procecess but only for the
> querying.

I mean ETL to load data _INTO_ data warehouse. Of course, complexity is mostly determined by sources, but still I'd like to know if there is any general influence by DW's data model.

Another question. Is it feasible to make date dimension or just use date column? For example, Oracle Discoverer can work with date columns using hierarchies Y->M->D and similar.
What is faster: separate table for date dimension or date column? If I go with date dimension table should I use date column as a foreign key in fact table or use some artificial key?

TIA,
Alexandre

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