What is ETL?
Answer: ETL stands for Extract, Transform, Load. It's a process used to extract data from various sources, transform it into a consistent format, and then load it into a target database or data warehouse.
What are the main components of ETL process?
Answer:
Extraction: Gathering data from different sources.
Transformation: Converting and standardizing the data.
Loading: Storing the data into a target system.
What is the difference between ETL and ELT?
Answer: In ETL, data is extracted, transformed, and then loaded into a target system. In ELT, data is first extracted, then loaded into a target system, and finally transformed.
Explain the importance of ETL testing.
Answer: ETL testing ensures that data is accurately transformed and loaded into the target system without any loss or corruption.
What are the types of ETL testing?
Answer:
Source to Target Count Verification
Data Completeness
Data Transformation
Data Quality
Performance and Scalability
What is a Data Warehouse?
Answer: A data warehouse is a central repository for storing large volumes of structured data from various sources. It is designed for query and analysis rather than transaction processing.
What is the staging area in ETL?
Answer: The staging area is an intermediate storage area where raw data is loaded before it undergoes the transformation process.
What are the different types of ETL tools you have worked with?
Answer: Mention specific ETL tools you are familiar with, such as Informatica, Talend, Microsoft SSIS, etc.
Explain the concept of data lineage in ETL.
Answer: Data lineage is the path that data takes from its source to its destination. It shows how data is transformed and aggregated through different stages of the ETL process.
What is a slowly changing dimension?
Answer: Slowly changing dimensions (SCD) are dimensions that change over time, but not with the same frequency. There are three types of SCDs: Type 1 (overwrite), Type 2 (add new row), and Type 3 (add new column).
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