Some RDBMSes like Oracle let you give hints about how you want things joined, which is usually what you mean when you say you want to specify the query plan. I

Some RDBMSes like Oracle let you give hints about how you want things joined, which is usually what you mean when you say you want to specify the query plan. I think I would like to see that in Postgres, but I don't think it's a common requirement. Usually you can just update the statistics to get the planner on the same page as you. I just like to have options in the toolbox, just in case I need them.