Re: Data Warehouse question

Hi Hans Pfeiffer,

What is this materialized view?
--
Michael,

I would suggest denormalize the FACT table as for as possible for the Data Warehouses. That would improve the performance to greater levels in the on-line analysis (say using Oracle Discoverer etc) of DW data.

regards

In article <37A4D66D.AF52989F_at_t-online.de>,   Hans-Friedrich Pfeiffer <Pfeiffer.Hans-Friedrich_at_t-online.de> wrote:
> michael_bialik_at_my-deja.com wrote:
> >
> > Hi,
> >
> > What is the better way :
> > 1. To keep a "fact" table and a number of "dimension"
> > tables separate ( perform a star join for each
> > query ), or
> > 2. Denormalize the tables and avoid the joins.
> >
> > Fact table - 3M - 4M rows.
> > Dimension tables - 20 - 30K rows max.
> >
> > Thanx. Michael.
> >
> > Sent via Deja.com http://www.deja.com/
> > Share what you know. Learn what you don't.
>
> Hi,
>
> when you already use fact tables, I think your fact table is
> denormalized.
> Using facts and dimensions has the great advantage that you can query
> your facts
> by your dimensions. Queries or later demands of queries are much
> simplier then.
>
> I use a star schema for a data warehouse database.
> For the performance :
> think about using mmaterialized views in Oracle 8i. I use them
> frequently
> and the performance is GREAT ! I have tables of 70.000.000 entries (
> fact )
> and in general 3 to 5 dimension tables - you image the join ? Using
> materialized views is a clever answer to performance questions.
>
> Greetings
>
> Hans Pfeiffer
>

--
Nandakumar
Systems Analyst
New York
(N.Kumar_at_rocketmail.com)

Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't. Received on Mon Aug 02 1999 - 09:58:05 CDT