Olap reorganises data into a form that is meaningful to people
and businesses, writes Nick Langley
What is it?
Online analytical processing (Olap) is a method of extracting
business information by organising data into "dimensions" such as
product, sales territory, customers and sales period.
Users can devise queries to find out, for example, whether
particular products are selling poorly in certain areas. Olap
enables them to drill deeper into the information (for example, the
performance of individual stores or salespeople) or take an
historical view (ie, have new products always been slow to take off
in this territory?)
Once restricted to professional analysts using complex and
expensive products, Olap technology has been incorporated into
business intelligence tools such as those from Cognos and Brio. It
entered the mainstream with Microsoft's SQL Server 7, which
incorporated an Olap engine.
Where did it originate?
The first recognisable Olap product was Express, released in 1970,
which is still going strong as part of Oracle's Olap offering. The
best known Olap product, Essbase, was launched in 1992.
The term "Olap" was coined by Ted Codd, father of the relational
database, in 1993. But Codd's paper was sponsored by Arbor, the
company behind Essbase, and other suppliers denounced Codd's
definition as too product-specific.
IBM released its DB2 Olap Server, a version of Essbase, in 1998.
SQL Server 7 came out in 1999, bundling what was then called Olap
Services, now Analysis Services.
What is it for?
There are two types of Olap. Relational Olap (Rolap) works directly
against relational databases. Multidimensional Olap, or Molap,
works on summary databases.
Molap is better on small bodies of information; Rolap is more
scalable. Molap has richer analytical functions, but Rolap can go
down to a more granular level. Rolap uses the underlying strengths
of the relational database, but Molap is easier for non-technical
users. There is also a class of hybrid Olap products (Holap).
Fortunately, these Olap terminologies are gradually dying
out.
What makes it special?
Databases store data in the tabular form computers prefer. Olap
enables information to be reorganised in a way that is meaningful
to people and businesses.
How difficult is it?
Early Olap products were toolkits for building queries. Now most
come with vast libraries of predefined queries, which suppliers
claim meet 80% of needs. The other 20% must be defined by
professional analysts.
There is a lot of grunt work involved in making data suitable for
Olap: merging multiple sources, cleaning data up, and making it
complete and consistent.
Where is it used?
In sales analysis, database marketing, clickstream analysis and
management reporting.
Not to be confused with...
A Scandinavian christian name.
What does it run on?
The Olap Report
(www.olapreport.com) says
more than 30 suppliers claim to provide Olap products. The market
leaders are Microsoft and Essbase (Hyperion).
Few people know that...
Up to half of all Olap seat licences bought are never deployed. "A
tribute to the skills of Olap sales people, or a sad indictment of
project success rates," says the Olap Report.
What's coming up?
XML for Analysis, an XML-based Olap application programming
interface developed by Microsoft, Hyperion and the SAS
Institute.
Training
Independent training organisations offer courses for users of
IBM, Essbase, and especially Microsoft Olap products. For others
you will need to contact the supplier.
Rates of pay
Olap analysts can expect £25,000 to £30,000, while
datawarehouse architects can command £50,000+. Microsoft jobs are
easier to come by but pay less.