Data Warehouse (DW)
In computing, a data warehouse (DW or DWH), also known as an enterprise data warehouse (EDW), is a system used for reporting and data analysis. DWs are central repositories of integrated data from one or more disparate sources. They store current and historical data and are used for creating trending reports for senior management reporting such as annual and quarterly comparisons.
The data stored in the warehouse is uploaded from the operational systems (such as marketing, sales, etc The data may pass through an operational data store for additional operations before it is used in the DW for reporting.
ETL is short for extract, transform, load, three database functions that are combined into one tool to pull data out of one database and place it into another database.
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Extract is the process of reading data from a database.
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Transform is the process of converting the extracted data from its previous form into the form it needs to be in so that it can be placed into another database. Transformation occurs by using rules or lookup tables or by combining the data with other data.
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Load is the process of writing the data into the target database.
ETL is used to migrate data from one database to another, to formdata marts and data warehouses and also to convert databases from one format or type to another.
