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.