[postdb]

I started with mysql in late 90's, switched to postgre and would prefer that instead of MySQL if it is my decision. MySQL is faster than postgres is a myth. Please see this https://arctype.com/blog/performance-difference-between-post...

One thing mysql is better than postgres is that mysql can fast replicate across different data centers. See this blog: https://www.uber.com/en-DK/blog/postgres-to-mysql-migration/

However what Uber is doing may not be what you doing. So do some research and hire qualified db admin or devop people to make the informed choice.