Aaron Bertand only likes the right kind, by which I mean the left kind:
The headline is probably unfair and is not meant to imply that a RIGHT OUTER JOIN is wrong. But when I see a RIGHT OUTER JOIN, my first thought is, “the rest of this review will probably be harder than it needs to be.” I find that it makes queries harder to read, because most people naturally read queries left-to-right. With a left join, the “important” table is on the left, and the query is saying, “give me everything from this table, and maybe something from this related table.” With a right join, I have to mentally flip things around to understand which table is important.
Aaron is absolutely right about left-handed scissors. I extend this as well to can openers and a half-dozen other tools that fit very well in the right hand but are quite awkward for southpaws. And don’t get me started on writing.
Aaron is kinder toward RIGHT OUTER JOIN than I am. I’m not convinced there’s ever a reason that we should use RIGHT OUTER JOIN. LEFT OUTER JOIN is much easier for humans to interpret, and (save for very specific scenarios) we should optimize code for human interpretability over pretty much anything else. And yes, that includes (again, save for very specific scenarios) performance.