PostgreSQL when it is not your job
Some of the suggestions make PostgreSQL seem less mature than InnoDB, still: "[don't put] sessions in the DB", "[don't put] constantly-updated counters in the database", and "[don't put] task queues in the database."<p>My forum gets almost a million page views daily; we store all our data in a(n) InnoDB database, including sessions, task queues, and constantly updated counters. They work just fine and are not even bottlenecks when the isolation level is REPEATABLE READ.<p>We use SERIALIZABLE though, as a matter of principle, so we had to implement a more fancy schema, but everything happens in the InnoDB database. We don't have to worry about running VACUUM periodically either. I feel PostgreSQL may be a wee bit overhyped.