When you read data from a Netezza source, transform the data, and write the data to a target, you can configure SQL ELT optimization to push the transformation logic to the source or target database system.
You can configure SQL ELT optimization when you use a Netezza ODBC connection that uses Netezza ODBC drivers in the mapping.
If the source and target databases are the same, you can configure full SQL ELT optimization for improved performance.
When the Secure Agent applies SQL ELT optimization, it pushes transformation logic to a database. The Secure Agent translates the transformation logic into SQL queries and sends the SQL queries to the database. The database runs the SQL queries to process the transformations.
SQL ELT optimization improves mapping performance when the database can process the transformation logic faster than the Secure Agent. The Secure Agent also reads less data from the database.
The amount of transformation logic that the Secure Agent pushes to the database depends on the database, the transformation logic, and the mapping task. The Secure Agent processes all transformation logic that it cannot push to a database.
When you configure SQL ELT optimization for the mapping, the Secure Agent analyzes the optimized mapping from the source to the target or until it reaches a downstream transformation that it cannot push to the source database. The Secure Agent generates and executes a SELECT statement for each source that has transformation logic pushed down. Then, it reads the results of this SQL query and processes the remaining transformations in the mapping.
You cannot use SQL ELT optimization when you run a mapping in advanced mode.