Data Warehousing

The term Data Warehouse was coined by Bill Inmon in 1990, which

he defined in the following way:

• "A warehouse is a subject-oriented, integrated, stable and volatile collection of data in support of management's decision making process".

• "A warehouse is a subject-oriented,integrated, time-variant and non-volatile collection of data in support of management's decision making process".

• Both A and B

• None of above

Which is difficult topic in this unit?

• OLAP SERVER

• DATA WAREHOUSING ARCHITECTURE

• STAR SCHEMA

• FACT CONSTELLATION

Definition of Subject Oriented Data: Data that gives information about a particular subject

instead of about a company's ongoing operations.

• True

• False

Definition of Integrated Data: Data that is gathered into the data warehouse from a variety of sources and merged into a coherent whole.

• True

• False

Your opinion about use of ROLAP and MOLAP.

Benefits of Data warehousing are:

1. Data warehouses are designed to perform well with aggregate queries running on large amounts of data.

2. The structure of data warehouses is easier for end users to navigate, understand and query against unlike the relational databases primarily designed to handle lots of transactions.

3. Data warehouses enable queries that cut across different segments of a company's operation. E.g. production data could be compared against inventory data even if they were originally stored in different databases with different structures.

4. Queries that would be complex in very normalized databases could be easier to build and maintain in data warehouses, decreasing the workload on transaction systems.

5. Data warehousing is an efficient way to manage and report on data that is from a variety of sources, non uniform and scattered throughout a company.

6. Data warehousing is an efficient way to manage demand for lots of information from lots of users.

• 1,2,4,6

• 1,3,2,5

• 1,2,3,4

• 1,2,3,4,5,6

Select easiest topic in this unit

• OLTP vs OLAP

• OLAP servers

• Architecture

• Schemas

Operational Data is:

• Focusing on transactional function such as bank card withdrawals and deposits

• Detailed

• Updateable and Reflects current data

• All of above

Explain Data mart with example

Informational Data is:

• Focusing on providing answers to problems posed by decision makers

• Summarized

• Non updateable

• All of above