The Free On-line Dictionary of Computing (30 December 2018):

drill down
drill-down analysis

    (Or "drill-down analysis") To examine data in
   greater detail, especially, in reporting, to interactively
   select some item from a summary and display the data that
   contributed to that item, broken down by some extra parameter.

   For example, when viewing your company's total worldwide sales
   for each month of this year, you might drill down to see
   October's sales by country, then again to see October's sales
   in Afghanistan by product and so on.

   This kind of analysis is often supported by some kind of data
   warehouse.

   (2007-06-04)