There is a setting in the web.config file to enable MDX query logging. Set:<add key="Bpm.EnableAnalyticQueryLogging" value="True" />
Note: as with any web.config file change, you have to make it in 3 places - by default:
C:\Program Files\Microsoft Office PerformancePoint Server\3.0\Monitoring\PPSMonitoring_1\Preview
C:\Program Files\Microsoft Office PerformancePoint Server\3.0\Monitoring\PPSMonitoring_1\WebService
Keep in mind that the above paths are examples; the actual paths may vary by SharePoint site & Monitoring instance ("PPSMonitoring_1") name.
The MDX query will appear as an Information entry in the Application event log.
Viewing MDX as a Dashboard Designer user:
In CTP3, you can view (and alter, if you like) the MDX being run. Design your query on the cleverly-named "Design" tab, then flip to the mysterious "Query" tab to see the MDX generated by Dashboard Designer.
Greg Bernhardt (email@example.com)