Query optimizer messages are available only when explaining queries from the Run SQL Scripts window (proactive case). The optimizer messages appear in the tab titled Optimizer Messages in the bottom pane of the window. These messages represent a subset of all debug messages contained in the job log.
To display the messages from the optimizer:
Tip: To see detailed message text, double-click on the message. A second double-click will collapse the message text again. To view all job log messages, access the job log from Run SQL Scripts.