code: func (cwc *ColWithCmpFuncManager) CompareRow(lhs, rhs chunk.Row) int {
  	for i, col := range cwc.affectedColSchema.Columns {
  		ret := cwc.compareFuncs[i](lhs, col.Index, rhs, col.Index)
  		if ret != 0 {
  			return ret
  		}
  	}
  	return 0
  }
docs: // CompareRow compares the rows for deduplicate.