Cookie vs MySQL Save

Question

I guess this is more of just a personal preference questions, but I'm really concerned with performance. I'm working on a little project and one thing that people can do is RSVP to events. Now I know the option that people choose (attend or not attend) must be stored in a database, but to make the site look a little better, I also want the button that allows someone to attend switch to not attend when they click it.

At this point I'm thinking of three options, either query the database, figure out if the person is attending, and display the appropriate button. -OR- I could save the information in a cookie and just pray that the user doesn't delete the information. -OR- I could save the information in a cookie, if the cookie is present then display whatever the cookies says, if not then query the database. Option 3 seems the best to me.

I always kind of inspect major sites and look at some of the techniques they use. They tend to keep the cookie count under 20. Is there anything bad about option 3, or is it the way I should go. Thanks!

Answer 1

Store it in the db. If the user logs in on a 2nd machine and changes the status, the wrong status will show when they go back to the 1st machine.

Answer 2

Without the details on how people access the site, whether they are logged in or not, it is hard to say but I would agree with you on the 3rd option - query the cookie first if there i nothing, query the database - which works as long as no two people use the same computer session.

Another option that may work (or not depending on your web app) is to have individualized links. This can work nicely if people come to your site from email links with a url similar to this http://example.com/[eventid]/[uniquecode]

Answer 3

If you use cookie, you can expect that there is some other person who uses the same machine, the same user account, the same browser, the same settings. There can be also a person who uses different browsers. There can be also two persons who share two computers.

If the users log in you can use sessions, it is cookie, of course, but you can identify the user, so he knows "it's not me".

And about performance: if you set your cookie, it takes also time to get it and then send it, via http headers and responses. But the best idea would be to benchmark this. Because of the small time to access db and for the reasons I stated before, I would use the db.