code: func (la *LogicalAggregation) canPullUp() bool {
  	if len(la.GroupByItems) > 0 {
  		return false
  	}
  	for _, f := range la.AggFuncs {
  		for _, arg := range f.Args {
  			expr := expression.EvaluateExprWithNull(la.ctx, la.children[0].Schema(), arg)
  			if con, ok := expr.(*expression.Constant); !ok || !con.Value.IsNull() {
  				return false
  			}
  		}
  	}
  	return true
  }
docs: // canPullUp checks if an aggregation can be pulled up. An aggregate function like count(*) cannot be pulled up.