Learn about how to use ETL and ELT processes in Exasol.
An ETL process divides the transfer of data from a source system into a target system in three stages:
- Extract: The reading of data from the source systems.
- Transform: Various data modifications, customization of data types, elimination of duplicates, aggregation, and standardization of heterogeneous data structures.
- Load: Writing data in the target system.
The source systems usually involve one or more operational databases, whose data is combined into a target system. The process begins with an initial full load, followed by periodic incremental loading of data to keep the data warehouse updated. In Exasol, you can use SQL statements in the database instead of ETL tools to perform more complex data transformation than the data type conversion, such as data modifications, aggregation, or schema manipulations.
ELT
For optimum performance we recommend that you use ELT processes in Exasol instead of ETL. In an ELT process, the transformation phase is performed after the extract and load phases. Because ELT exploits the high performance of a parallel cluster for complex operations, we recommend using ELT instead of ETL whenever possible. To learn more, see Best practices.
