Project(Extend(Extend(AggregationJoin(Aggregation(??agg1: ?p, SAMPLE,
                                                  {},
                                                  G1=Group((?p),
                                                     Project(BGP( ?s ?p ?o),
                                                     {?p}))),
                                      Aggregation(??agg2: ?p, COUNT, {}, G1)),
                      ?p,
                      ??agg1),
               ?count,
               ??agg2),
        {?p, ?count})