OLAP technology brings together a number of precise terms designating the
elements of multidimensional structures. In addition, you will also come across several specific abbreviations
in the OLAP world. We therefore need a glossary.
This glossary is only intended to illuminate, and is not a full and strict
source of reference. Your (constructive) criticisms will help it to evolve.
- The act of calculating values associated with parent positions in the hierarchical dimensions.
This consolidation may be by addition, averaging or by other more complex processes like second strongest value.
- A fact describing each position of a dimension.
- Synonym for dimension.
- A piece of data defined by its position in each dimension. The cells of
can be empty or full. When a large number of cells are empty the data is said to be "sparse".
- Most often a synonym for hypercube.
- Data mart
- The data relating to one of the jobs of the company. Several data marts form
the data warehouse of the firm.
- Data warehouse
- A warehouse of data. Indicates all the data of the company, stored in a
common data-processing form.
- A collection of data of the same type, allowing us to structure the multidimensional
database. A dimension is sometimes referred to as an axis. In a measure, each cell of data is associated with one single position in each dimension. Time, Location
and Product are the classic dimensions.
- Desktop OLAP. Small OLAP products for local multidimensional analysis Desktop
OLAP. There can be a mini multidimensional database (using Personal Express), or extraction of a datacube (using
- Decision Support System. It's a data interrogation
and presentation system, specifically used for decision-making. The french equivalent is SIAD, or "Système
d'Information d'Aide à la Décision".
- Executive Information System. The english term more commonly used is DSS,
or Decision Support System.
- Fast Analysis of Shared Multidimensional Information. These five words all
have their place in the definition of OLAP technology.
- A virtual hypercube. The values are often calculated on the fly, and not
stored in the database.
- The positions of a dimension organised according to a series of cascading
one to many relationships. This way of organizing data is comparable to a logical tree, where each member has only
one parent but a variable number of children.
- Hierarchy level
- In a hierarchy, positions are classified into levels. All the positions
for a level correspond to a unique classification. For example, in a "Time" dimension, level one stands
for days, level two for months and level three for years.
- Hybrid OLAP. Designates multidimensional analysis tools which store data
in either relational or multidimensional databases, in a transparent way for the user.
- A multidimensional construction formed by the conjunction of several dimensions.
is defined by a single member of each dimension.
- Multidimensional database. Allows storage, manipulation and reproduction
of multidimensional data.
- A hypercube, most often an integer or decimal type, structured by the dimensions.
Salary, Value and Quantity are classic measures.
- Multidimensional OLAP. This term designates a cartesian data structure more
specifically. In effect, MOLAP contrasts with ROLAP. Inb the former, joins between tables are already suitable, which enhances performances.
In the latter, joins are computed during the request.
- A multidimensional construction formed from several hypercubes sharing certain
- Data structure having at least three independent dimensions.
- Literally, On-Line Analytical Processing. Designates a category of applications
and technologies that allow the collection, storage, manipulation and reproduction of multidimensional data, with
the goal of analysis. Another definition is contained in the acronym FASMI (Fast Analysis of Shared Multidimensional Information). OLAP tools have to follow
12 rules, described on this page.
- A value of a dimension. Also called a dimension member.
- Relational database Management System. Allow storage, manipulation and reproduction
of data stored in relational tables. The french equivalent is SGBDR.
- A relation between the positions of two dimensions is a good way to make
on-the-fly calculations, and thus easily create formulas.
- Relational OLAP. Designates one or several star schemas stored in relational
databases. This technology permits multidimensional analysis with data stored in relational databases.
- "Système de Gestion de Base de Données Relationnelle".
French translation of RDBMS.
- "Système d'Information d'Aide à la Décision".
French translation of EIS.
- Star schema
- Arrangement of data in a relational database. In the middle is the fact
table, whose columns constitute the multidimensional measures. The branches of the star, which radiate from the
fact table, correspond to the dimensions. The conceptual data model represents
this star schema.
- Normally a synonym for measure.
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Last update 09/28/2000