you can certainly encode queue in many ways. mkfifo just work. But integrating the queue in the DB isn't a bad idea if you want to have both the queue and the db in a shared state.

I am happy that my queue inherit ACID properties.

SQLite simply doesn't allow concurrent write so it is a no go for a queue.

I don't know much about SQL Server and MySQL but I wouldn't favor a lockin closed source software or anything remotely connected to Oracle.

At the end, only Postgresql remains I guess. Also, Postgresql is super solid and the closest to SQL standard.