[mirntyfirty]

True, even with tuned indices table scans are pretty frequent and perhaps one would want a slower but cheaper query. It’d be quite stressful to have to worry about query plans executed because they can vary quite a bit across very similar queries and be nudged towards more expensive queries by development teams.

[fabian2k]

If your application allows somewhat flexible queries this might also create potential Denial of Money attacks, which I personally find scarier than plain old Denial of Service. I mean that's always a risk with this type of pricing, but the particulars of a relational database with a query planner makes this a lot more dangerous.