> Composites are not allowed to contain instances of themselves within any of their fields Do you mean recursive type definitions? Or? Who does allow that? And

> Composites are not allowed to contain instances of themselves within any of their fields Do you mean recursive type definitions? Or? Who does allow that? And what would you use it for in an SQL context? Please elaborate, I'm curious what you are getting at here. > Table inheritance doesn't work well with uniqueness constraints This got somewhat better in postgresql 11 (beta1 is available now) in that unique works for partitioned tables. I don't know if that also includes inherited tables, they are similar but not the same. Partitioned tables are the case most people are interested in anyway.