Tuning Nested Aggregate Function Behavior
Several data sources support nested aggregate functions, but some do not. Meanwhile, checking for these functions can significantly slow performance. You can use a TDV configuration parameter to decide whether or not to check SQL queries for nested aggregate functions.
For example, Netezza does not support nested aggregate functions, so you can improve performance by setting the Check if nested aggregates is supported by datasource to False for queries pushed to a Netezza data source.
A nested aggregate function looks like this:
SELECT AVG(MAX(salary)) FROM employees GROUP BY department_id;
To look for nested aggregate functions in SQL
1. Open and log into Studio.
2. From the Administration menu, choose Configuration.
3. Navigate to and select Check if nested aggregates is supported by datasource.
4. Select True.