results

benchmark     iterations    time/iteration   delta  delta%
---------     ----------    --------------   -----  ------
BenchmarkV1      50000	    380653 ns/op
BenchmarkV2     100000	    355788 ns/op     -24865 -6.5%
BenchmarkV3     100000	    357934 ns/op     -22719 -5.9%

v1

func v1() {
	db := getDb()

	tx, _ := db.Begin()

	result, _ := tx.Exec("INSERT INTO orders (created) VALUES (?)", time.Now())
	orderID, _ := result.LastInsertId()

	_, _ = tx.Exec("INSERT INTO orderItems (order_id, added) VALUES (?, ?)", orderID, time.Now())

	tx.Commit()
}

v2

func v2() {
	db := getDb()

	result, _ := db.Exec("INSERT INTO orders (created) VALUES (?)", time.Now())
	orderID, _ := result.LastInsertId()

	_, _ = db.Exec("INSERT INTO orderItems (order_id, added) VALUES (?, ?)", orderID, time.Now())
}

v3

func v3() {
	db := getDb()

	result, _ := db.Exec("INSERT INTO orders (created) VALUES (?)", time.Now())
	orderID, _ := result.LastInsertId()

	// introduce "fake" errors from the first INSERT statement
	if isError(1) {
		_, _ = db.Exec("DELETE FROM orders WHERE id = ?", orderID)
		return
	}

	_, _ = db.Exec("INSERT INTO orderItems (order_id, added) VALUES (?, ?)", orderID, time.Now())
}

func isError(percentage int) bool {
	return rand.Intn(100) < percentage
}