Data Warehouse Design - Chapter 1.1 & 1.2

Question 1

Why is datawarehousing invented?

Answer 1

The larger one’s company is, or the larger their database becomes, the harder it becomes to retrieve your desired data for analytical processing.

You often have to use extensive SQL codes and it can take up to hours.

Therefore, data warehousing is implemented to minimize slowig down the system and to maximize the ability to do analytical decisionmaking

Question 2

What is OLAP?

Answer 2

Online Analytical Processing

Question 3

What is OLTP?

Answer 3

Online Transactional Processing

Question 4

What is operational data?

Answer 4

Data created by business operations invovled in daily management processes.

Question 5

Why are computers the only suitable tools for decision-making?

Answer 5

Because of the exponential increase in operational data.

Question 6

What is a decision support system (DSS)?

Answer 6

A set of expandable, interactive, IT techniques and tools designed for processing and analyzing data and for supporting managers in decision making.

To do this, the system matches individual resources of managers with computer resources to improve the quality of decisions made.

-> Does not slow the operational systems down

Question 7

How does a DSS look like from an architectual viewpoint?

Answer 7

1. Model based management system that is connected to
2. A knowledge engine
3. A graphical user interface.

Question 8

What is a passive DSS?

Answer 8

Supports decision-making processes, but it does not offer explicit suggestions on decisions or solutions

Question 9

What is an active DSS?

Answer 9

Offers suggestions and solutions

Question 10

What is a collaborative DSS?

Answer 10

Operates interactively and allows decisionmakers to modify, integrate, or refine suggestions given by the system.
Suggestions are sent back to the system for validation

Question 11

What is a model-driven DSS?

Answer 11

Enhances management of statistical, financial, optimization and simulation models

Question 12

What is a communication-driven DSS?

Answer 12

Supports a group of people working on a common task.

Question 13

What is a data-driven DSS?

Answer 13

Enhances the access and management of time series of corporate and external data.

Question 14

What is a document-driven DSS?

Answer 14

Manages and processes nonstructured data in many formats.

Question 15

What is a knowledge-driven DSS?

Answer 15

Provides problem-solving features in the form of facts, rules and procedures.

Question 16

What is data warehousing?

Answer 16

A collection of methods, techniques, and tools used to support knowledge workers - senior managers, directors, managers and analysts - to conduct data analyses that help with performing decision-making processes and improving information resources.

Question 17

What are mandatory requirements for a datawarehouse process?

To turn operational data into information that can be used to support decision-making?

Answer 17

1. Accesibility to users that are not familiar with data
2. Intergration of data on the basis of a standard model
3. Query flexibility to maximize the obtained advantages from existing information
4. Information conciseness to allow for target-oriented and effective analyses
5. Multidimensional representation to give users a manageable view of information
6. Correctness and completeness of integrated data

Question 18

What is a data warehouse and what are its three features?

Answer 18

A collection of data that supports decision-making processes and has the following features:

1. It is subject-oriented
2. It is integrated and consistent
3. It shows its evolution over time and it is not volatile

Question 19

What are three effects of data never being deleted from a data warehouse?

Answer 19

1. Satisfies the users’ need for a short analysis query response time
2. There is no need for advanced transaction management techniques (as in operational databases)
3. Data warehouses are read-only making it more acceptable to de-normalize data to improve performance.

Question 20

What are the three main differences between an operational database and a datawarehouse?

Answer 20

1. Operational data covers a short period of time, whereas a datawarehouse covers a period of time.
2. Data in operational databases can be added, removed or modified. This does not happen in a data warehouse.
3. Operational queries focus on a small number of tables and their relations. Data warehouse queries focus on huge amounts of data and queries.