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.
- Extract is the process of reading data from a database. In this stage, the data is collected, often from multiple and different types of sources.
- 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.
- Load is the process of writing the data into the target database.
How ETL Works
Data from one or more sources is extracted and then copied to the data warehouse. When dealing with large volumes of data and multiple source systems, the data is consolidated. ETL is used to migrate data from one database to another, and is often the specific process required to load data to and from data marts and data warehouses, but is a process that is also used to to large convert (transform) databases from one format or type to another.
ETL and Business Intelligence
ETL is an important part of today‘s business intelligence (BI) processes and systems. It is the IT process from which data from disparate sources can be put in one place to programmatically analyze and discover business insights.
转载自：https://www.webopedia.com/TERM/E/ETL.html
原文：https://www.cnblogs.com/harry1989/p/12002952.html
