DMC DMC ETL Processes & Data Warehousing 2

Question 1

Which of the following best describes a data warehouse according to Bill Inmon's definition?

Accepted Answer

A subject-oriented, integrated, time-variant, non-volatile collection of data for decision support

Answer

Inmon defined a data warehouse as subject-oriented, integrated, time-variant, and non-volatile — properties that distinguish it from operational databases.

Question 2

What is a 'star schema' in data warehouse design?

Accepted Answer

A central fact table connected directly to multiple denormalized dimension tables

Answer

The star schema features a central fact table linked directly to denormalized dimension tables, creating a star shape that simplifies query writing.

Question 3

How does a 'snowflake schema' differ from a star schema?

Accepted Answer

Dimension tables are normalized into multiple related sub-tables

Answer

In a snowflake schema, dimension tables are normalized into related sub-tables, reducing data redundancy at the cost of increased query complexity.

Question 4

What is a 'fact table' in a data warehouse?

Accepted Answer

A table that stores measurable, quantitative data about business events

Answer

A fact table stores quantitative measurements about business events — such as sales amounts or order quantities — and links to dimension tables via foreign keys.

Question 5

What is a 'slowly changing dimension' (SCD) in data warehousing?

Accepted Answer

A dimension where attribute values change gradually over time and must be tracked historically

Answer

A slowly changing dimension tracks how dimension attributes change over time — such as customer address updates — with different SCD types managing history retention differently.

DMC - Data Mining Certification Practice Test

DMC - Data Mining Certification Practice Test

DMC DMC ETL Processes & Data Warehousing 2