Most commonly asked Data Warehouse & Informatica ETL Interview Questions with Answer: Set 1

Most commonly asked Data Warehouse & Informatica ETL Interview Questions with Answer: Set 1

1.Define data warehouse?

Data warehouse is center point storage with restricted access. 

2.What does subject-oriented data warehouse signify?

Organized around major subjects, Focusing on the modeling and analysis of data for decision makers, not on daily operations or transaction processing.

3.List any five applications of data warehouse.

customer goods, banking services, retail sectors, financial services,  controlled manufacturing.

4.What do OLAP and OLTP stand for?

OLAP: Online analytical process

OLTP: Online transaction process.

5.What are the benefits of data warehouse?

Better decision-making, Quick and easy access to data, Data quality and consistency.

6.Why Data Warehouse is used?

A data warehouse integrates data from multiple sources correctly. 

7.What is the difference between OLTP and OLAP?

OLTP database is detailed and current data, and schema used to store transactional databases is the entity model (usually 3NF).

OLAP database is aggregated, historical data, stored in multi-dimensional schemas (usually star schema).

8.What is the very basic difference between data warehouse and operational databases?

A data warehouse consists of historical data which is made available for analysis of the business. 

Operational database consists of current data which is mandatory to run the business.

9.What do you mean by Data Extraction?

Data extraction meanspulling data from various different sources.

10.Define metadata?

Metadata is defined as data about data which is summarized data that leads to the detailed data.

11.What does Metadata Respiratory contain?

Metadata respiratory is consists of definition of data warehouse, business metadata, operational metadata, data for mapping from operational environment to data warehouse &the algorithms for summarization.

12.Define dimension?

The dimensions are the entities with respect to which an enterprise keeps the records.

13.Explain data mart.

Data mart contains data specific to a particular subject.

14.What is Virtual Warehouse?

The view over an operational data warehouse is known as virtual warehouse.

15.Define load manager.

A load manager performs the operations required to extract and load the process.

16.Define the functions of a load manager.

A load manager extracts data from the source system. Fast load the extracted data into temporary data storage. Perform simple transformations into structure similar to the one in the data warehouse.

17.Define a warehouse manager.

The warehouse manager consist of third party system software, C programs and shell scripts and responsible for the warehouse management process.

18.What is ER model?

Entity Relationship model.

19.What is Fact?

A fact is an event that is counted or measured, such as a sale or login.

20.What is Star-schema?

Star schema is the simplest form of a dimensional model, in which data is organized into facts and dimensions.