What is Extract Transform Load (ETL)?
Extract Transform Load (ETL) is the process of extracting, transforming, and loading during database usage, but especially during data store usage.
It includes the following sub-processes:
- Retrieve data from external data storage or transmission sources
Transforming data into an understandable format in which data is typically stored along with error detection and correction code to meet operational requirements
- Transferring and loading data to the receiving end
The first phase of an ETL process focuses on getting the data from the storage source. Most data storage projects integrate data received from various source systems. Each individual system can use a separate data organization or a separate data format. Common data source structures are relational databases and pure data files.
They can also contain non-relational database patterns such as information management systems or other data structures such as VSAM (Virtual Storage Access Method) or ISAM (Indexed Sequential Access Method). Data sources can even contain external sources, e.g. B. Data from the Internet or via a scanning system.
The transformation phase uses a series of rules or operations to retrieve pure data from the source in order to deliver the data in its final form for manipulation at the receiving end. Some data sources require very little or no data processing. Sometimes one or more transformations can be critical to meet the business and technical needs of the target database.
The load or transfer stage aims to send data to the receiving end, which is likely to be a data store. Depending on the needs of the application, this process can be very simple or very complicated. Some data storage methods can replace old data with cumulative data. The extracted data is usually updated at regular intervals.