message: Issue Streaming Windowed Aggregates
  Reduce slicing overhead.
  This improves performance by another 10x.
diff: @@ -152,13 +152,20 @@ OperatorResultType PhysicalStreamingWindow::Execute(ExecutionContext &context, D
  payload.Initialize(executor.allocator, payload_types);
  executor.Execute(input, payload);
  - // Update the state and finalize it one row at a time.
  + // Iterate through them using a single SV
  + payload.Flatten();
  DataChunk row;
  row.Initialize(allocator, payload_types);
  - for (sel_t i = 0; i < input.size(); ++i) {
  - row.Reset();
  - SelectionVector sel(&i);
  - row.Slice(payload, sel, 1);
  + sel_t s = 0;
  + SelectionVector sel(&s);
  + row.Slice(sel, 1);
  + for (size_t col_idx = 0; col_idx < payload.ColumnCount(); ++col_idx) {
  + DictionaryVector::Child(row.data[col_idx]).Reference(payload.data[col_idx]);
  + }
  +
  + // Update the state and finalize it one row at a time.
  + for (idx_t i = 0; i < input.size(); ++i) {
  + sel.set_index(0, i);
  aggregate.update(row.data.data(), aggr_input_data, row.ColumnCount(), statev, 1);
  aggregate.finalize(statev, aggr_input_data, result, 1, i);
  }
  