DMC ETL Processes & Data Warehousing Flashcards

What is a 'data mart'?

Answer: A subset of a data warehouse focused on a specific business area or department

A data mart is a department- or subject-focused subset of a data warehouse, providing targeted data access for a specific business audience.

Which OLAP operation moves from summarized data to more detailed data?

Answer: Drill down — navigates from summary data to more granular detail

Drilling down moves from higher-level summaries to more detailed data — for example, from annual sales totals down to individual daily transactions.

What is a 'surrogate key' in data warehouse design?

Answer: A system-generated artificial integer used as the primary key in dimension tables

A surrogate key is a system-generated, meaningless integer assigned as the primary key in dimension tables, independent of source system identifiers.

What is a 'conformed dimension' in data warehousing?

Answer: A dimension shared and used consistently across multiple fact tables or data marts

A conformed dimension is standardized and shared across multiple fact tables or subject-area data marts to ensure consistent enterprise-wide reporting.

What is the purpose of a 'data lineage' system in ETL?

Answer: To track the origin and complete transformation history of data through the pipeline

Data lineage tracks the complete history of data as it flows through the ETL pipeline — from its source origin through every transformation to its final destination.

What is 'data granularity' in a data warehouse?

Answer: The level of detail stored in a fact table

Data granularity refers to the level of detail captured in fact table rows — finer granularity means individual transactions, while coarser granularity means aggregated summaries.