How to alter session parameter "_unnest_subquery" for tuning session? (4225707)

How do you alter a session parameter for a tuning session? I want to tune a query, original as is, and an alternate with 'alter session set "_unnest_subquery"=FALSE'. I found the "Alter Session Parameters" option from the right-click menu in the SQL pane, but "_unnest_subquery" is not listed.

WORKAROUND:

1. Tune the SQL as normal for the first open Optimizer session to get the alternatives and run stats for the original SQL. 

2. Then create a script that includes the alter session parameter command

3. Go to Options | General | Options, check the "Execute Login Script" setting and browse to specify the script. 

4. Open a second Optimizer tab/session and tune the SQL (you can either tune the original again or just an alternate). This time the script will be executed for the connection and used in this session. 

You will need to disable the setting and/or remove the file after you're done so it doesn't affect other sessions you work with in Optimizer.

STATUS:

Enhancement request ST81689 has been submitted to Development for consideration in a future release of Quest SQL Optimizer for Oracle.