message: Issue Nested join payloads
  Make sure deserialisation vectors
  are marked as flat, not constant.
diff: @@ -853,6 +853,8 @@ static void DeserializeIntoListVector(Vector &v, const idx_t vcount, const Selec
  void RowDataCollection::DeserializeIntoVector(Vector &v, const idx_t &vcount, const SelectionVector &sel,
  const idx_t &col_no, data_ptr_t key_locations[],
  data_ptr_t validitymask_locations[]) {
  + v.SetVectorType(VectorType::FLAT_VECTOR);
  +
  auto &validity = FlatVector::Validity(v);
  if (validitymask_locations) {
  // Precompute mask indexes
  