It's much less emphasized compared to MySQL, I didn't even know about it until your comment, and search results are sparse.

MySQL has had multiple viable storage engines for most of its existence. MyISAM, InnoDB and more recently MyRocks.

You might be able to argue that Postgres' foreign data is a different form of pluggable storage engine. E.g. you can even use a CSV file as a backing store for a table with file_fdw.

https://www.postgresql.org/docs/current/ddl-foreign-data.htm...

https://dbaclass.com/article/how-to-access-csv-files-on-file...

Someone should do an experience report on adding the same storage system to both databases.

What you say looks powerful but Facebook added their MyRocks to MySQL.