Hi, author of the blog post here. I hope this was helpful and happy to answer any questions.

Curious that the database of choice for payments was MongoDB, what was the process behind this decision?

As we wrote in the blog post, we chose to build our database infrastructure on top of MongoDB Community because of the flexibility of its document model and its ability to handle massive volumes of real-time data at scale. MongoDB Atlas didn’t exist in 2011, so we spun up a self-managed cluster of MongoDB instances running in the cloud.

How many people does it take to run it?