Oracle-L: RE: RE: Using dimensions

From: DENNIS WILLIAMS <DWILLIAMS_at_lifetouch.com>
Date: Mon, 29 Sep 2003 12:20:10 -0800
Message-ID: <F001.005D1641.20030929122010@fatcity.com>

Ryan, Stephane

Here is the way I would put it, based on my admittedly small experience:

The in the star schema design, dimension hierarchy gives users a clearer way to select data. Often in the GUI screen they have pull-down boxes for the hierarchies.
The regularity of the star schema not only allows users to easier access, but for software tools like Oracle to implement performance features aimed at the star schema. For example, there is the STAR_TRANSFORMATION hint. Other Oracle features that are really useful in DW are bitmap indexes, materialized views, and partitioning. You may not use any of these on your DW, but if you have a tough performance problem, these can be really useful.

Dennis Williams
DBA, 80%OCP, 100% DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----
Sent: Monday, September 29, 2003 2:55 PM To: Multiple recipients of list ORACLE-L

so basically your saying you use dimensions hand in hand with materialized views.

do they have other uses?
>
> From: "Stephane Paquette" <stephane.paquette_at_standardlife.ca>
> Date: 2003/09/29 Mon PM 02:39:43 EDT
> To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> Subject: RE: RE: Using dimensions
>
> Using dimensionsI`ve not used dimensions in Oracle only read about them.
> But I have designed DW using dimensional modeling. So from what I've read
in
> the doc, Oracle will used the dimensions to be better at query rewriting
> because it knows the hierarchy of the data (example : neighbourhood, city,
> region, province, country)
>
> Stephane Paquette
> Administrateur de bases de donnees
>
> Database Administrator
>
> Standard Life
>
> www.standardlife.ca
>
> Tel. (514) 499-7999 7470 and (514) 925-7187
>
> stephane.paquette_at_standardlife.ca
>
> -----Original Message-----
> From: ml-errors_at_fatcity.com [mailto:ml-errors_at_fatcity.com]On Behalf Of
> rgaffuri_at_cox.net
> Sent: Monday, September 29, 2003 2:20 PM
> To: Multiple recipients of list ORACLE-L
> Subject: Re: RE: Using dimensions
>
>
> Thanks Scott, okay lets forget OLTP .. but I haven't seen any _actual_
> uses of dimensions ... where does one use them? in SQLs?
>
> I have scanned TFM, but haven't STFW'd yet ... scared of too many hits.
>
> Thanks
> Raj
>

> ------
> Rajendra dot Jamadagni at nospamespn dot com
> All Views expressed in this email are strictly personal.
> QOTD: Any clod can have facts, having an opinion is an art !
> -----Original Message-----
> From: Scott Canaan [mailto:srcdco_at_rit.edu]
> Sent: Monday, September 29, 2003 11:55 AM
> To: Multiple recipients of list ORACLE-L
> Subject: RE: Using dimensions
>
>
> Dimensions are data warehouse constructs. They are implemented as
> tables in the database, but have the characteristic of a hierarchy that
can
> be traversed. For example: a time dimension can have the hierarchy of
> date, day, week, month, quarter, year, decade, century. This is used for
> rollup reporting within the data mart. I don't see any good use of it in
an
> OLTP environment, but I may be wrong.
>
>
>
> Scott Canaan (srcdco_at_rit.edu)
>
> (585) 475-7886
>
> "Life is like a sewer, what you get out of it depends on what you put
> into it." - Tom Lehrer.
>
>
>
> -----Original Message-----
> From: Jamadagni, Rajendra [mailto:Rajendra.Jamadagni_at_espn.com]
> Sent: Monday, September 29, 2003 10:55 AM
> To: Multiple recipients of list ORACLE-L
> Subject: Using dimensions
>
>
>
> I have tried, but haven't found a good example of how to _use_ a
> dimension in 9ir2. I defined one, but then sat clueless on what to do with
> it. Is it any good in an OLTP environment? (I smell the answer is a NO,
but
> still) ...
>
> Any notes from your experience?
>
> TIA
> Raj
>

> --------
> Rajendra dot Jamadagni at nospamespn dot com
> All Views expressed in this email are strictly personal.
> QOTD: Any clod can have facts, having an opinion is an art !
>
>
>

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Author: DENNIS WILLIAMS
  INET: DWILLIAMS_at_LIFETOUCH.COM

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Received on Mon Sep 29 2003 - 15:20:10 CDT