The dashboard wants three slices in a single result: event counts by type, event counts by user, and the grand total across all events. Running three queries and stitching them via union is ugly and inefficient: one grouping over several sets of columns delivers everything in a single pass. Show event type, user id, and event count — for the «by type only», «by user only», and «grand total» slices. In the by-type slice the user id is empty; in the by-user slice the type is empty; in the grand-total row both are empty. Sort by event type (empty values last), then by user id (empty values last too).