A data warehouse is a repository or data store in which data is stored, queried, and analyzed. The data comes from different sources like marketing research data, educational data, political data, scientific data, company data etc. A data warehouse is just like a store in which you store unused items like an electric generator or extra things. But in the case of a data warehouse, you store structural and semi-structured data.
A data warehouse acts as a central repository where data from different departments comes and then stored. New data warehouses use cloud technology to store data which is fast and easy to maintain.
What is ETL:
ETL means to extract, transform, and load. It means data is first extracted from different sources like spreadsheets or transactional databases. Then data is transformed meaning data is converted to meaningful form. Finally, data is loaded into the system.
A data warehouse can also be extended in the horizontal form to make it store more data in it. A data warehouse keeps historical data in it and then compares it with new data to make decisions.
Some types of data warehouse are:-
- Operational data store
- Enterprise data warehouse
- Virtual data warehouse
- Data warehouse appliance
- Data lake
- Cloud data warehouse
- Data mart
Characteristics of data warehouse
Some characteristics of a data warehouse are:-
- It can store large amounts of data
- It has strict policies to store data
- Once data is stored, it will not be changed or removed
- It takes regular backups for recovery purposes
- It has a user-friendly interface
- Data is stored in columns and rows in the database
Examples of data warehouse
Some examples of data warehouses are:-
- Google BigQuery
- Snowflake
- Firebolt
- Cloudera
- Amazon Web Services