ETL Testing Trivia 3

Question 1

What is a 'surrogate key' commonly used for in ETL data warehousing?

Accepted Answer

To provide a system-generated unique identifier independent of source business keys

Answer

A surrogate key is a system-generated integer assigned in the data warehouse to uniquely identify dimension records, independent of the source system's natural key.

Question 2

In ETL testing, what does 'data profiling' help testers accomplish?

Accepted Answer

Analyzing source data to understand its structure, quality, and anomalies before designing transformations

Answer

Data profiling examines source data's content, structure, and quality — such as null rates, value distributions, and format patterns — to inform ETL design and testing.

Question 3

What kind of ETL defect would cause a customer's city field to appear in the state column of the target table?

Accepted Answer

Column mapping defect

Answer

A column mapping defect occurs when source columns are incorrectly mapped to target columns, causing data to land in the wrong field.

Question 4

Which ETL testing type checks that business rules encoded in transformations produce the correct output values?

Accepted Answer

Transformation testing

Answer

Transformation testing validates that the logic applied during the Transform phase correctly converts, aggregates, or filters source data according to business rules.

Question 5

What is 'CDC' (Change Data Capture) used for in ETL pipelines?

Accepted Answer

Identifying and capturing only the rows that changed in the source since the last extract

Answer

Change Data Capture (CDC) tracks and captures only the rows that were inserted, updated, or deleted in the source system since the previous ETL run.

ETL Testing - extract, transform, load Practice Test

ETL Testing - extract, transform, load Practice Test

ETL Testing Trivia 3