MULTIDIMENSIONAL DATA MODELS:-

DG Kaur

INDEX:-

1. Definition of Multidimensional Data Models?

2. Types of MDDM:-

a. Star Schema

b. Data Cube Schema

c. Snowflake Schema

d. Fact Constellation schema

(Global Schema)

MULTIDIMENSIONAL DATA MODEL:-

The MDDM was developed for implementing

data warehouse and data marts.

MDDM provide both a mechanism to store data

and a way for business analysis.

TYPES OF MDDM:-

A. Data Cube Model.

B. Star Schema Model

C. Snow Flake Schema Model

D. Fact Constellations Schema Model

(Global Schema)

DATA CUBE MODEL:-

When data is grouped or combined together in

multidimensional matrices called Data Cubes.

In 2 Dimension:- row & column or products.

In 3 Dimension:- one regions, products and fiscal

quarters. Regions

product

Reg 1 Reg 2 Reg 3

P1

P2

P3

p4

Fig:-Data Cube

CONT……….

Changing from one dimensional hierarchy to

another is early accomplished in data cube by a

technique called rotation.

STAR SCHEMA:-

It is the simplest form of data warehousing schema.

It consists one large central table (fact) containing the bulk of data and a set of smaller dimension tables one for each dimension .

Its entity relationship diagram between dimensions and fact table resembles a star where one fact table is connected to multiple dimensions or table.

EXAMPLE OF STAR SCHEMA:-

SNOW FLAKE SCHEMA:-

It is difficult from a star schema .

In this dimensional table are organized into

hierarchy by normalization them.

The Snow Flake Schema is represented by

centralized fact table which are connected to

multiple dimensions.

EXAMPLE OF SNOW FLAKE SCHEMA:-

FACT CONSTELLATIONS:-

It is a set of fact tables that shares some

dimensional tables.

It limits the possible queries for the data

warehouse.

THANK U……..

ANY QUERIES ?