Re: Question about OLAP, ROLAP etc.

From: paquette stephane <stephane_paquette_at_yahoo.com>
Date: Mon, 8 Jan 2001 00:18:47 -0800 (PST)
Message-Id: <10735.125952@fatcity.com>

You have 3 families in the olap world : rolap, molap and holap.
Rolap stands for relationnal olap meaning the users see their data organized in cubes with dimensions but the data is really store in a rdbms (Oracle). Molap stands for multidimensionnal olap, the users see their data organized in cubes with dimensions and the data is store in a mdbms (Oracle Express). Holap stands for hybrid olap, it is a combination of both world, Holos is a holap environnement.

Each olap has its strenghts and weaknesses. Rolap means that the rdbms will store data at a very fine grain, response time is usually slow. Molap means that a lot of queries have a finite answer, performance is usually critical and fast. Holap means that you have queries on aggregated data as well as on detailed data.

I played with the Oracle Data Marts Suite 2 years ago , it was a bundle of half of Designer2000, an Oracle database, Discoverer, Oracle Web server and the heart of the product was the ETL tool provided by Sagent. The product was only running on NT at that time.

Oracle Express is multidimensionnal database meaning it is storing data like in a cube. It's a proprietary environment.

The DataMart suite and Express are different products and are not included with Oracle8i.

Most of the time, you build cubes for a type of users and let another type of users access the detailed data.

• Helmut Daiminger <hdaiminger_at_vivonet.com> a écrit : > Hi there!
  >
  > We are about to introduce Data Warehousing into our
  > shop and I haven't had
  > much exposure to that so far.
  >
  > I have a question about OLAP and ROLAP. I know what
  > the expressions mean,
  > but I don't know what the big difference between
  > those two are. When are
  > they used? And what are the advantages/disadvantages
  > between the two?
  >
  > What the Oracle Tools 'Data Mart' and 'Oracle
  > Express' good for? Is part of
  > their functionality already in 8i? And Oracle is
  > going to move functionality
  > into 9i, right?
  >
  > Any input would be appreciated.
  >
  >
  > This is 8.1.6 on Win2k.
  >
  >
  > Thanks,
  > Helmut
  >
  > --
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Stephane Paquette
DBA Oracle
stephane_paquette_at_yahoo.com

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Received on Mon Jan 08 2001 - 02:18:47 CST