[yjftsjthsd-h]

My first choice would be something like "this query will cost $13953, which exceeds your default cap of $100; please click the confirm button if you really want to run it". (The dollars could be CPU-minutes or whatever if you want to use resource based limits, which might play nicer with a free tier)

Edit: rereading, I think this is actually for non-interactive scripts, in which case yes it should just cancel the query

Edit 2: https://news.ycombinator.com/item?id=39447499 was kind enough to point out that the resource-based version of this might actually exist, which is nice