-- { echo }
EXPLAIN header = 1, optimize = 0 SELECT avgWeighted(x, y) FROM (SELECT NULL, 255 AS x, 1 AS y UNION ALL SELECT y, NULL AS x, 1 AS y);
Expression (Projection)
Header: avgWeighted(x, y) Nullable(Float64)
  Expression (Before ORDER BY)
  Header: avgWeighted(x, y) Nullable(Float64)
    Aggregating
    Header: avgWeighted(x, y) Nullable(Float64)
      Expression (Before GROUP BY)
      Header: x Nullable(UInt8)
              y UInt8
        Union
        Header: x Nullable(UInt8)
                y UInt8
          Expression (Conversion before UNION)
          Header: x Nullable(UInt8)
                  y UInt8
            Expression (Projection)
            Header: x UInt8
                    y UInt8
              Expression (Before ORDER BY)
              Header: 255 UInt8
                      1 UInt8
                      dummy UInt8
                ReadFromStorage (SystemOne)
                Header: dummy UInt8
          Expression (Conversion before UNION)
          Header: x Nullable(UInt8)
                  y UInt8
            Expression (Projection)
            Header: x Nullable(Nothing)
                    y UInt8
              Expression (Before ORDER BY)
              Header: NULL Nullable(Nothing)
                      1 UInt8
                      dummy UInt8
                ReadFromStorage (SystemOne)
                Header: dummy UInt8
SELECT avgWeighted(x, y) FROM (SELECT NULL, 255 AS x, 1 AS y UNION ALL SELECT y, NULL AS x, 1 AS y);
255