InterSystems IRIS Business Intelligence Tips & Tricks: Preview Mode
Preview Mode was added to InterSystems IRIS Business Intelligence to give designers a quick view of what their resulting Pivot Table will look like without needing to wait for the results to fully execute. This can be beneficial when designing pivot tables because if you are dragging and dropping elements to see how they look/work in your pivot table and seeing if they have the desired data. Since you are exploring and designing, you don't necessarily care about the results at the moment, but you would still like to see how your table looks with the changes you have made.
I previously wrote "DeepSee Tips & Tricks: Auto-execute" which can also be beneficial while designing Pivot Tables. However, with Auto-execute, you see no preview after dragging and dropping elements. It is more geared towards someone who knows exactly what their end result will be, someone who wants to prevent the intermediate executions while dragging and dropping elements. Preview Mode is more for exploring what the data looks like and how it can work in the Pivot Table.
At any point, you can simply turn Preview Mode off by using the checkbox at the top of Analyzer. You can also click the "Show All" button towards the bottom of Analyzer to see the full results of the current pivot. Adding new elements will continue to execute in Preview Mode.
The Documentation also has a brief explanation about Preview Mode.