DMC ETL Processes & Data Warehousing Flashcards

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

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

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

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

Answer: A central fact table connected directly to multiple denormalized dimension tables

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

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

Answer: Dimension tables are normalized into multiple related sub-tables

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

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

Answer: A table that stores measurable, quantitative data about business events

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

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

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

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

What does OLAP stand for in data warehousing?

Answer: Online Analytical Processing

OLAP stands for Online Analytical Processing, which supports multidimensional data analysis for complex queries and business decision support.