2. Three tier Architecture of Data Warehousing
1. The bottom tire is a warehouse database server that is almost always a relational database system. Data from operational databases are external sources are extracted using application program interfaces known as gateways. A gateway is supported by underlying DBMS and allows client programs to generate SQL code to be executed at a server. Example of Gateways include ODBC, OLE-DB and JDBC.

3. Three tier Architecture of Data Warehousing (Cont..)
2. The middle tire is an OLAP server that is typically implemented using either a relational OLAP (ROLAP) model, that is. an extended relational DBMS that maps operations on multidimensional OLAP(MOLAP) model, that is a special purpose server that directly implements multidimensional data and operations.

4. Three tier Architecture of Data Warehousing (Cont..)
3.The top tire is a client, which contains query and reporting tools, analysis tools. And/or data mining tools (e.g trend analysis,prediction, and so on)

5. Multi-dimensional Data Model
A multidimensional data model views data in the form of a data cube.
A data cube allows data to be modeled
and viewed in multiple dimensions. It is defined by dimensions and facts.
Dimensions are the perspectives or entities with respect to which an organization wants to keep records.
It represents data by means of a multidimensional N grid Q which is Cartesian product of certain discrete sets Di called dimension.
Elements of a dimensions are called members.
The set of dimension & members forms metadata.

6. Example Loc= Chicago Loc= New York Loc=Toronto Loc= Vancouver Item
home
ent. Comp. phone Sec.
Time Q1 Q2 Q3 Q4

7. Multi-dimensional Data Model
Dimensions: Product, Region, Time
Hierarchical summarization paths
Product Region Time
Industry Country Year
Category Region Quarter
Product City Month week
Office Day
Region W S N
Product
Toothpaste
Juice
Cola
Milk
Cream
Soap
Month 1 2 3 4 7 6 5

8. Representation of cube

10. What is OLAP
OLAP allows to model data in a multidimensional way like a data cube in order to look for the data from many perspectives.

11. Types of OLAP MOLAP: Hyperion (Arbor Essbase), Oracle Express
ROLAP: Informix MetaCube, Microstrategy DSS Agent
HOLAP: Microsoft SQL server 7.0