I'm new to web programming, and I've read that one of the reasons to avoid using Ajax to deliver too much of your content is because that content is effectively hidden from search engines. This makes sense to me.
I've just come across the data- attribute in HTML5. There seems to be no limit to the length of the string value you can place in it. Does the data-* attribute suffer from the same fault as Ajaxing stuff? Does google store values in these attributes as meaningful page information, or is it just ignored?
(I don't have a specific problem, so I don't know whether this question meets stackoverflow's criteria, I'm just genuinely curious, and couldn't find much information on my own -- partly because I didn't know what to search for because I'm relatively new to the topic.)