ETL Testing Basic 3

Question 1

Which ETL load strategy completely replaces all existing target table data with freshly extracted source data?

Accepted Answer

Full refresh (truncate and reload)

Answer

A full refresh truncates the target table first and then loads all source records, making it simple but costly for large datasets.

Question 2

In ETL, 'data latency' refers to:

Accepted Answer

The delay between when data is created in the source system and when it becomes available in the target

Answer

Data latency measures the lag between a business event occurring in the source and that data being queryable in the data warehouse.

Question 3

What is the purpose of a 'reject file' in ETL processing?

Accepted Answer

To hold records that failed validation so they can be reviewed and corrected without stopping the job

Answer

A reject file captures bad records (e.g., type mismatches, constraint violations) so the ETL job can continue while those records are separately investigated.

Question 4

Slowly Changing Dimension (SCD) Type 2 testing verifies that:

Accepted Answer

A new row is inserted for each attribute change, preserving the full history with effective dates

Answer

SCD Type 2 inserts a new dimension row for each change and marks the old row as expired, enabling historical reporting.

Question 5

ETL throughput, a key performance metric, is typically measured as:

Accepted Answer

Rows or megabytes processed per second or per hour

Answer

Throughput quantifies how much data the ETL pipeline processes in a given time unit and is the primary metric in ETL performance testing.

ETL Testing - extract, transform, load Practice Test

ETL Testing - extract, transform, load Practice Test

ETL Testing Basic 3