Multiindex.union

Author: phofl

pandas/core/indexes/multi.py

@@ -3522,14 +3522,9 @@ def equal_levels(self, other) -> bool:
 
     def _union(self, other, sort):
         other, result_names = self._convert_can_do_setop(other)
+        result = super()._union(other, sort)
 
-        # We could get here with CategoricalIndex other
-        rvals = other._values.astype(object, copy=False)
-        uniq_tuples = lib.fast_unique_multiple([self._values, rvals], sort=sort)
-
-        return MultiIndex.from_arrays(
-            zip(*uniq_tuples), sortorder=0, names=result_names
-        )
+        return MultiIndex.from_tuples(result, sortorder=0, names=result_names)
 
     def _is_comparable_dtype(self, dtype: DtypeObj) -> bool:
         return is_object_dtype(dtype)