I am fetching some questions from the server (database) and showing it to client (user) in the browser. The client will answer the question and based on his/her answer the next set of questions will be fetched from the database. Now, I want to pre-fetch the next set of questions while the user read the present question so that the waiting time for user to see the next question will be shorter.
My questions is, how to store the pre-fetched questions i.e. which data structure should I use to store the pre-fetched questions in the memory so that I can get better performance? I want a “cache” type of thing. Also once the user hit any question from the cache the question won’t be there any more.
PS: Each question has unique Id.
Thanks
Naveen
There are multiple options to go about it. One that makes a big difference, one that makes little.
Little difference would be to fetch questions and store it in user’s session. It’s basically depends on where your session is stored, could also be database, or a file. This only makes sense if your db tables are very denormalized and it requires lots of joins to get the answer. I doubt that’s the case so this won’t make much difference for the user no matter which data structure used.
Big difference would make prefetching them with AJAX using javascript straight into the browser. In this case a simple array would suffice. JS gives you flexibility to build any objects with any properties, anything would be good enough. So write a poller in JS which fetches the questions from server while user is looking at the question, return them using JSON for example. JSON will become a simple object. Since each user stores only a couple of questions prefetched in their browser particular data structure choice won’t make a difference here either.