Scaling relational databases can be hard especially if you don't take the time upfront to prepare for it. Replication, denormalization, and federation are all explored in this article.
After reading this article, you will understand how to export data from a database or other system using a csv library in Node.js. CSV stands for common separated values file which means that data can be stored in a tabular format with commas separating each value.
AWS has hundreds of services available through their console or through their SDK. Amazon RDS is one of the most commonly used services. Amazon RDS standards for Relational Database Service - essentially it's a large collection of different SQL databases.
For the most part, it seems to be that NodeSQL databases are the defacto standard with Node and JavaScript developers. Using MySQL is still an option and can make a lot of sense if the project already has an existing database.
Knex is a JavaScript / Node.js library that is designed to make working with relational databases easier. Knex.js is a SQL query builder. It has the potential to make tdd and database versioning much easier.