ETL Testing ETL Data Loading Strategies 3

Question 1

Which ETL loading test verifies that a new load run does not destroy historical data that should be preserved?

Accepted Answer

Historical data preservation / regression test

Answer

A historical data preservation test confirms that incremental or SCD loads do not inadvertently overwrite or delete records that represent past states required for historical analysis.

Question 2

What is 'parallel loading' in ETL, and what risk must testers watch for?

Accepted Answer

Loading data into multiple target partitions or tables simultaneously; risk is deadlocks or race conditions

Answer

Parallel loading improves throughput by writing to multiple target locations simultaneously, but testers must verify there are no deadlocks, duplicate inserts, or race conditions.

Question 3

In ETL testing, a 'load reconciliation report' is used to:

Accepted Answer

Compare record counts and key aggregates between staging and target to confirm load completeness and accuracy

Answer

A load reconciliation report validates that row counts, sum totals, and key metrics match between the staging layer and the final target, confirming a successful load.

Question 4

Which scenario requires a 'restart and recovery' test in ETL loading?

Accepted Answer

When the ETL load fails midway and must resume from the failure point without re-loading already-inserted records

Answer

Restart and recovery tests verify that if an ETL load fails partway through, the job can resume from a checkpoint and complete without duplicating previously loaded records.

Question 5

What does 'load sequencing' mean in ETL, and why does it matter for testing?

Accepted Answer

The order in which tables are loaded to respect foreign key dependencies — parent tables must be loaded before child tables

Answer

Load sequencing ensures parent/dimension tables are populated before child/fact tables so that foreign key constraints are not violated during loading.

ETL Testing - extract, transform, load Practice Test

ETL Testing - extract, transform, load Practice Test

ETL Testing ETL Data Loading Strategies 3