Interview Questions

Difference between Database and Data Warehouse Testing - ETL

ETL (extract, transform, and load) Testing Interview Questions

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87. Difference between Database and Data Warehouse Testing - ETL

There is a popular misunderstanding that database testing and data warehouse is similar while the fact is that both hold different direction in testing.

Database testing is done using smaller scale of data normally with OLTP (Online transaction processing) type of databases while data warehouse testing is done with large volume with data involving OLAP (online analytical processing) databases.
In database testing normally data is consistently injected from uniform sources while in data warehouse testing most of the data comes from different kind of data sources which are sequentially inconsistent.
We generally perform only CRUD (Create, read, update and delete) operation in database testing while in data warehouse testing we use read-only (Select) operation.
Normalized databases are used in DB testing while demoralized DB is used in data warehouse testing.

There are number of universal verifications that have to be carried out for any kind of data warehouse testing. Below is the list of objects that are treated as essential for validation in ETL testing:
- Verify that data transformation from source to destination works as expected
- Verify that expected data is added in target system
- Verify that all DB fields and field data is loaded without any truncation
- Verify data checksum for record count match
- Verify that for rejected data proper error logs are generated with all details
- Verify NULL value fields
- Verify that duplicate data is not loaded
- Verify data integrity

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