code: func CopySelectedJoinRows(src *Chunk, innerColOffset, outerColOffset int, selected []bool, dst *Chunk) bool {
  	if src.NumRows() == 0 {
  		return false
  	}
  
  	numSelected := copySelectedInnerRows(innerColOffset, outerColOffset, src, selected, dst)
  	copyOuterRows(innerColOffset, outerColOffset, src, numSelected, dst)
  	dst.numVirtualRows += numSelected
  	return numSelected > 0
  }
docs: // CopySelectedJoinRows copies the selected joined rows from the source Chunk
  // to the destination Chunk.
  // Return true if at least one joined row was selected.
  //
  // NOTE: All the outer rows in the source Chunk should be the same.