I have an online exam application (MCQ type questions) i have questions table and user_answers table and every test will have 100 questions right now i am using this approach,
at first i have created user_answers table and when user click on question options as answer i am storing question_id, user_answer and time taken in table and if user changes the option i am using update query to update the answer so i am doing like this for all 100 questions so when user clicks end exam i am just changing the user_test column status as complete. this is working fine for below 500 users at a time. but when it reaches more than 1000 users at a time then it is giving I/0 problem. is this correct way or any performance tweaks that can be done?
Please help me with this.