When I first started making Ruby on Rails apps, the choice between Postgres and MySQL was not as clear as it is today. Postgres has emerged as the clear winner for Rails developers, and I recently decided to update my Rails apps to use Postgres instead of MySQL. This was a problem because I had already paid for several years of MySQL RDS reserved instances (RIs) and Amazon Web Services did not allow me to change those instances to Postgres through the web interface.
My mom's computer was running pretty slowly, so she asked me to troubleshoot it and try to find a way to speed it up. I checked the activity monitor on her computer and found that her hard drive's disk usage was often pegged at 100% while her CPU (central processing unit) and RAM (random-access memory) had plenty of headroom. Since she was using a HDD (hard disk drive), I advised her to upgrade to an SSD (solid-state disk).