I understand that the SQL user probably doesn't have any sort of permission to modify the database, and that very heavy caching is probably used in addition to the fact that this is on a data dump instead of the live database, but how the heck is the data explorer not lagging like crazy from the fact that any user on the internet at all can run any select query he or she desires? I'd imagine the server load would be enormous. Is there any sort of filtering going on to ensure malicious queries are not run? Is it even possible to run a query that could be considered malicious? I know the database itself is safe, but surely all these arbitrarily run queries would slow the server down to a crawl?
Pardon my curiousity, I've just never been allowed to run arbitrary SQL on someone else's server with absolutely no inherently visible limits excluding the fact that the database is read-only.
EDIT: It seems the access we're allowed goes deeper than I thought. I also noticed people's queries like this one making tables and inserting data into those tables. Are these tables cross-question? How is abuse prevented with these? Are the tables cached for that question only so the queries run more quickly?