It's almost certainly not SQL parsing that is introducing a serial component and an upper bound on parallelism. Actually, that is a task that is almost perfectly parallelizable. Parsing has no serial component, planning may have one if you somehow need locks on shared data structures needed for plan optimization.
MySQL and Postgresql are insanely different. To a point that it's uninteresting to compare them. MySQL is a keystore with an SQL frontend, which eventually got ACID features bolted on. Postgresql is a full-fledged RDBMS that eventually got refactored with performance in mind. While the end goal seems the same, the results are really different.
All of this text to say something which I think is common knowledge and is found interspersed in the comments here. For any kind of moderately complex query, Postgresql will eat Mysql's lunch. For any kind of concurrent locking, highly parallel, use case, Postgresql is much faster and/or safer. For any kind of very simple query, Mysql will eat Postgresql's lunch. It's a result of different upbringings.
If your use case can be satisfied with memcache, you aren't using a relational database and, yes, Mysql is the best choice, out of these two. Anyhow, in this scenario, today, there is a vast choice of good persistent keystores that are better than mysql.
MySQL and Postgresql are insanely different. To a point that it's uninteresting to compare them. MySQL is a keystore with an SQL frontend, which eventually got ACID features bolted on. Postgresql is a full-fledged RDBMS that eventually got refactored with performance in mind. While the end goal seems the same, the results are really different.
All of this text to say something which I think is common knowledge and is found interspersed in the comments here. For any kind of moderately complex query, Postgresql will eat Mysql's lunch. For any kind of concurrent locking, highly parallel, use case, Postgresql is much faster and/or safer. For any kind of very simple query, Mysql will eat Postgresql's lunch. It's a result of different upbringings.
If your use case can be satisfied with memcache, you aren't using a relational database and, yes, Mysql is the best choice, out of these two. Anyhow, in this scenario, today, there is a vast choice of good persistent keystores that are better than mysql.