Mumbai University > Information Technology > Sem 5 > Advanced Database Management System

Marks: 5M

Year: Dec 2014, May 2015

The following is the description of the layers of the data warehouse system:

1. Data source layer: Refers to the layer representing various data sources that data into the data warehouse. The data can be in any of these formats: plain text file, relational database, Excel file and other types of data that can act as data sources:

• Production sources: Represents sales data, HR data and product data
• Internal data: Represents data of a departed or an organization such as employee data.
• External data: Represents data from outside the organization or third party data such as census data or demographic or survey data.
• Achieved Data: Represents logs of the web server along with the user’s browsing data.

1. Data staging layer: Refers to the storage area for data processing where data comes before being transformed into the data that is entered in a data that is entered in a data warehouse. The following are the steps involved in transporting data from various sources to data warehouse:
2. Extraction:- Refers to the process of extracting data from different source system and validating it against certain quality
3. Transformation: Refers to the transformation of the data available in different source system and validating it against certain quality.
4. Loading: Refers to the process of loading the data either from data warehouse data mart.
5. Data storage layer: Refers to the layer in which the transformed data and cleaned data is stored. On the basis of the scope and functionality, the following are the types of entities in this stage:
6. Data warehouse: It is maintained by organizations as central warehouse of data that can be equally accessed by all business experts and end users.
7. Data Mart: When data warehouse is created at the department level, it is known as data mart.
8. Meta data:- Details about the data is known as metadata. In other words, it is a catalog of data warehouse.
9. MDDB:- It is multidimensional database that allows data to be molded and viewed in multiple dimensions. It is defined by dimensions and facts.
10. Information Delivery:- Provides the information that reached to end users. The information can be in any form such as tables, chart, graphs, or histograms. The following are the tools used in this layer:
11. Data mining: Refers to the process of finding relevant and useful information large amount of data.
12. OLAP:- Allows the navigation of data at different levels abstraction, such as down, roll-up, slice , dice, and so on.