ETL Testing ETL Data Loading Strategies 1

Question 1

What is a 'full load' in ETL data loading?

Accepted Answer

Truncating the target table and reloading all records from scratch each run

Answer

A full load completely replaces the target table contents on each ETL run by truncating and reloading all records from the source or staging area.

Question 2

Which loading strategy appends only new or changed records to the target without removing existing data?

Accepted Answer

Incremental load

Answer

Incremental loading merges new and changed records into the existing target data, preserving historical records while keeping the target current.

Question 3

In ETL loading testing, which validation confirms that primary key uniqueness is maintained after loading?

Accepted Answer

Duplicate key / uniqueness constraint test

Answer

A uniqueness constraint test queries the target for duplicate primary key values to ensure the load did not introduce any key violations.

Question 4

What is 'bulk loading' in ETL, and why is it preferred for large datasets?

Accepted Answer

Using database-native bulk utilities (e.g., SQL Server BCP, COPY in PostgreSQL) that bypass row-by-row processing for much faster throughput

Answer

Bulk loaders use optimized database utilities that write data in large blocks with minimal logging, achieving orders-of-magnitude faster throughput than row-by-row inserts.

Question 5

Which test verifies that foreign key relationships in the target remain valid after an ETL load?

Accepted Answer

Referential integrity test

Answer

Referential integrity testing queries the target to confirm that every foreign key value in child tables has a matching primary key in the parent table.

ETL Testing - extract, transform, load Practice Test

ETL Testing - extract, transform, load Practice Test

ETL Testing ETL Data Loading Strategies 1