I see that design question for PostgreSQL pluggable storages is very hard. BTW, I think it worth analyzing existing use-cases of pluggable storages. I think that the most famous DBMS with pluggable storage API is MySQL. This why I decided to start with it. I've added MySQL/MariaDB section on wiki page.
It appears that significant part of MySQL storage engines are misuses. MySQL lacks of various features like FDWs or writable views and so on. This is why developers created a lot of pluggable storages for that purposes. We definitely don't want something like this in PostgreSQL now. I created special resume column where I expressed whether it would be nice to have something like this table engine in PostgreSQL.
Any comments and additions are welcome. I'm planning to write similar table for MongoDB.
------ Alexander Korotkov Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
