I am writing a forum from scratch...

Bonesnap

I am writing a forum from scratch as a personal project, and just one of those "to see if I can do it" things. I don't really expect it to be used as a real forum, but several of my friends and I will be using it. I suppose one day if it's solid enough, I would actually try to get people to join.

My question is this: Is there an efficient/easy way to keep track of new posts and if an user has viewed them.

It seems to me it's certainly doable, but it would create an incredible strain on the database (the forum is backed by a MySQL database). Basically you would have to track every post for every user, and in the case of a popular forum with many users and may posts, this obviously causes some issues.

So I am wondering how to do it efficiently. I can rationalize how to check if a thread has a NEW post, but once I view that thread, I want to be able to look at the list of threads and see that one particular thread is marked as "no new posts". And, to take it a step further (since I've seen this in other forums), it would track threads with multiple pages. For example, if a thread had three pages, and I only viewed the first page, the thread would still be listed as having new posts.

I don't want to take the easy (and less accurate) way out and compare post times versus last login time, because that doesn't truly keep track. I can narrow it down to certain sections (the last time the user visited a section, compare that time to post times), but again, it doesn't truly keep track of new posts.

I suppose what's really bugging me about this is not the PHP code (I apologize if this is in the wrong section or not appropriate), but more so the logic behind it. If anyone can offer their expertise or suggestions, I would greatly appreciate it. Thank you for your time.

(By the way, this site is an excellent resource - I can't believe I haven't come here before)

sneakyimp

I would agree that keeping some association table between users and threads could get cumbersome (1,000 user times 1,000,000 threads would mean a billion records with somewhere around 8 bytes per record for a total of 8G😎. Such an assoc table would be searched reasonably fast thanks to indexing, but you would see performance hits under certain circumstances. I think you can forget about associating users and individual posts.

You could try storing a timestamp for each thread (which is updated each time a post is made) and compare that to the 'last login' on a given user's record. Create a session record or set a cookie or something when a user logs in or returns to a forum. When you create this record or cookie, fetch the 'last login' time from the database and then update it immediately. For the duration of that session, you will know the time of their previous login. Comparing the timestamp of the previous login to the timestamp on a given thread or post would be a reasonably good indication of which threads were 'new'.

sneakyimp

oops...didn't read your post closely enough -- you clearly said you didn't want to take that approach. I can't really think of a better way to do it right now. If you insist on keeping a 'last read' value associating each user with a given thread, you might want to only add or update a record in it when the user actually looks at the thread. Most people don't read all the threads so this would help keep your table size down.

Indexing is a pretty good way to get blazing performance out of a gigantic table like that. You can get additional speed by partitioning the table. It may just work after all.

Krik

You could try storing a timestamp for each thread (which is updated each time a post is made) and compare that to the 'last login' on a given user's record. Create a session record or set a cookie or something when a user logs in or returns to a forum. When you create this record or cookie, fetch the 'last login' time from the database and then update it immediately. For the duration of that session, you will know the time of their previous login. Comparing the timestamp of the previous login to the timestamp on a given thread or post would be a reasonably good indication of which threads were 'new'.

I built a forum from scratch last year. And that is how I handled it. But in my case it worked out well as I was logging user activity for the last 30 day for all users any way. So the date and time was all ready logged and would just compare it to time stamp on the last post in a thread.

On the idea of using an associative table you could do this just keep the time frame that it tracks posts down to 7 days. So even if you have 1 million posts it is only tracking those from the last 7 days which may be just a couple hundred. I believe that is how they do here on phpbuilder.

Bonesnap

Thank you for your input guys! I'm going to play around with it and see what I can do.

Eventually I'd like to include the "go to first new post" feature, but first I want to conquer this.

Thanks again!