go test --timeout 0 -v -benchmem -bench=BenchmarkVecEvalReal -count=20 -run=BenchmarkVecEvalReal | tee old.txt
go test --timeout 0 -v -benchmem -bench=BenchmarkVecEvalReal -count=20 -run=BenchmarkVecEvalReal | tee new.txt

benchstat old.txt new.txt
name                       old time/op    new time/op    delta
VecEvalReal/VecEvalReal-2    0.39ns ± 5%    0.38ns ± 6%  -2.44%  (p=0.003 n=18+20)

name                       old alloc/op   new alloc/op   delta
VecEvalReal/VecEvalReal-2     0.00B          0.00B         ~     (all equal)

name                       old allocs/op  new allocs/op  delta
VecEvalReal/VecEvalReal-2      0.00           0.00         ~     (all equal)

func BenchmarkVecEvalReal(b *testing.B){
	ctx := mock.NewContext()

	batchSize := []int{
		10,
		100,
		1000,
		100000,
	}

	for i:=0; i<len(batchSize); i++ {
		ft := types.NewFieldType(mysql.TypeFloat)
		col := &Column{RetType: ft, Index: 0}
		input := chunk.New([]*types.FieldType{ft}, batchSize[i], batchSize[i])
		for i := 0; i < batchSize[i]; i++ {
			input.AppendFloat32(0, float32(i))
		}
		result, err := newBuffer(types.ETReal, batchSize[i])
		if err != nil {
			panic(err)
		}
		b.Run(fmt.Sprintf("origin-%d", batchSize[i]), func(b *testing.B){
			col.VecEvalReal(ctx, input, result)
		})
		result, err = newBuffer(types.ETReal, batchSize[i])
	}
}