I am using a combination of ajax php and sql. I have a local copy of this program and a live sever run by a company, there is a button that posts a comment, on the local copy you can post a comment of any size, but on the live server I have narrowed it down to about 512 bytes once the comment gets larger than that, no error is generated but the comment isn't added, is there any configuration files concerning MySQL databases PHP or javascript that could limit the amount of data that can be parsed?
is the action of the form for posting comments GET or POST?
if it's POST: in the php.ini, there's a configuration called post_max_size (documentation), please take a look at that on your local- and production-server and compare the values.
if it's GET: some browsers limit the querystring to aroudn 2kb, so maybe you exceed this... you should use POST instead.
If it were me, I would probably use the "onSubmit" tag on the form an run a quick javascript validation on the input (a function called from onSubmit="return func(this)" will only transmit if func(this) returns true). Simply have it call a function, and if the value of the field has a string length and return a little alert window if there are more than 500 characters. That way you don't necessarily parse or transmit anything you don't have to.
You'll probably want to have a fallback so that someone with javascript disabled can't bypass those limits, but that should work for the majority of your users.
Ok there was a get max value paramater in php.ini (under the settings for shino or something like that that was on the live server) that was set to 512 I changed it so now the system can handle 10KB of text for comments