Having for the most part avoided the computer science department during my earth science education, this is helpful. I have sort of an intrinsic idea of what's

Having for the most part avoided the computer science department during my earth science education, this is helpful. I have sort of an intrinsic idea of what's going on -- self-joins can easily compare a data set with every other member of the data set, and hit O(N²). And that if your N is 5, the DB will probably going spend more time parsing SQL than executing your query, so no point in optimizing. So I don't understand or care about what the definition is, but it's useful tool to think about how slow your code can be.