ETL Testing ETL Data Extraction Techniques

Question 1

Which extraction method reads only the data that has changed since the last extraction, minimizing load on source systems?

Accepted Answer

Incremental extraction

Answer

Full extraction

Answer

Logical extraction

Answer

Online extraction

Question 2

What is a 'delta' in the context of ETL data extraction?

Accepted Answer

The difference or change in data since the last extraction

Answer

A Greek letter used in database naming

Answer

A full copy of the source table

Answer

A staging area database

Question 3

Which technique uses database log files to capture data changes for ETL extraction?

Accepted Answer

Log-based Change Data Capture (CDC)

Answer

Timestamp-based extraction

Answer

Trigger-based extraction

Answer

Full table scan

Question 4

When testing ETL extraction, which validation confirms that no source records were dropped during the pull?

Accepted Answer

Row count reconciliation

Answer

Data type check

Answer

Null value check

Answer

Duplicate check

Question 5

What does 'online extraction' mean in ETL testing?

Accepted Answer

Extracting data directly from a live, active production system

Answer

Extracting data from cloud-only sources

Answer

Extracting data via REST API only

Answer

Extracting data during scheduled downtime

Question 6

Which extraction type is MOST suitable when source systems do not support timestamps or change tracking?

Accepted Answer

Full extraction

Answer

Incremental extraction

Answer

Log-based CDC

Answer

Streaming extraction