Sessions Max Var. Size???

matty_x

Hi Folks,

Long time lurker, first time poster. I can't seem to find any info on this question I have. I am creating online instruction for my students, and this entails a series of forms that the students must fill out. The forms go over a series of pages, with intermittent pages inbetween where students can see their answers and see automated feedback to their answers. I want to avoid using hidden form fields, as this gets awkward after the third page or so 🙁, so I have opted for using PHP sessions for storing their data. Some of the responses that students will be provided will be rather lengthy (probably 5 to 7 paragraphs), and I'm wondering if I can store all of that information in a session variable. So my question is as follows:

Is there a set maximum size for session variables?

Also

Is there a maximum amount of variables that can be stored in the session array?

Thank you all for your input! 😃

Steveo31

I've done a lot of online research on PHP and I haven't seen anything about limits. I think it comes down to speed or the server when dealing with that amount of info.

Just curious, why are you storing such large amounts of data is SESSION vars? Why not have em in a database or textfile or something?

tekky

the best solution to something like this...

try it, if it works let us know for future reference, if not.... we'll help you with an alternate solution....

when it comes to programming, you can never be afraid to try something just to see if it works... If it does, awesome, if it doesn't... what have you lost? Nothing... simply gained more knowledge of whatever you are programming right? 😉

matty_x

Thanks for the responses folks. I did more research into this and was unable to discover any information about session sizes. So I decided to test the size of a session variable. I piped the output from /var/log/messages into a file called test_size.txt (the file turned out to be around 2.6 M😎. Then I copied the entire file into one of the textboxes in a form and submitted the form, which adds the form data to the session. Used "print_r" to see the contents of the session, and it can hold the ENTIRE contents of the test.txt file(!). But it did take about one minute for my poor little 300MHZ laptop to serve the page. I was pleasantly surprised 😃 I'm not necessarily concerned with speed since this class is only intended for about 12-15 students, so there will not be high volume traffic to this site.

As far as the question about using databases/textfiles is concerned, I am using a database. However, for simplicity's sake I decided to only have one call to the database to dump the contents of the session. And, if I understand sessions correctly, isn't a session just a special text file that is stored on the server?

In any case, thank you all for your input and I hope I was able to add a little to the discussion. See you around on the boards!

Weedpacket

Originally posted by matty_x
As far as the question about using databases/textfiles is concerned, I am using a database. However, for simplicity's sake I decided to only have one call to the database to dump the contents of the session. And, if I understand sessions correctly, isn't a session just a special text file that is stored on the server?

That's the default installation - not everyone has a dbms on their server, and its performance is good enough for most - but it is possible to write session handlers that e.g., access a database instead. PHP will then use those handlers instead of its default ones for the various session-related tasks it does.

If you're interested the page to start on is probably that for [man]session_set_save_handler[/man], which gives example code for mimicking the default file-based storage.

matty_x

Hi Weedpacket ;-)

Thanks for the information. That sounds like something I would be very interested in. I will look into it and post my results.

Thanks again!