There Are Only 3 Databases You Can Trust With Your Money
Why the most popular choices are the most risky, and which ones to choose instead.
“The nature of promises, Linda”, Frank Underwood said in the pilot of House of Cards, “is that they remain immune to changing circumstances.”
He was talking about the president-elect’s promise to nominate him as Secretary of State, but we may feel the same outrage and betrayal about “open source” databases: Redis being BSD-licensed until 2025; Elasticsearch being Apache 2.0 until 2021; and MongoDB being AGPL until 2018.
Frank was wrong, of course.
Promises are not immune to changing circumstances. Open source databases have to face the pressure of two, in particular:
Having a cloud provider like AWS productizing your database and eating your main source of funding (also known as getting Jeff’d)
Having the VCs you’ve raised funds from pressuring you into capturing the market instead of serving the community built around your database.
Unlike choosing a logging library or a linter, the database is the foundation of financial systems because most money software’s value is derived from its data. Once a database is chosen and deployed in production, it becomes incredibly difficult and expensive to migrate away from.
The problem, however, is made worse by the fact that engineers are often the least reliable judges when it comes to choosing databases.
Under the veil of “best tool for the job”, many engineers argue endlessly about what the best database is based on a combination of past experience, CV-driven development, and marketing. Confronted with a database choice, they go for the familiar, the shiny, or the coolest new thing.
And that’s how you get SQLite rewritten in Rust.
Engineers are often dismissive of marketing done to others, but are helpless to the marketing done to them: open source databases most likely to appear in the Stack Overflow Developer Survey are VC-funded1.
The problem with the effectiveness of marketing is that the databases most likely to hurt you down the line are often the ones “most admired” and “most popular”. If engineers weren’t so susceptible, database choice would be more niche and less “general purpose”, and cloud providers wouldn’t be so prone to “Jeff” them. We probably wouldn’t have VC-funded databases to begin with.
But we would know which promises to trust.
I’m Alvaro Duran, and this is The Payments Engineer Playbook. There is a lot of content out there on how to choose a database for money software. Most of it, however, is marketing. The Playbook is the only newsletter on Earth tailor-made for engineers of money software, which teaches you how to design money software, not to pass interviews, but to handle real users and real money.
Every week, more than 2,000 subscribers from companies like Stripe, Coinbase and Modern Treasury get a deep dive on how to build software that moves money around.
This week, we’re going to investigate one of the most crucial questions that every CTO must face before building money software: which database should I use? And since I can’t make that choice for you, because I don’t have your full context, today’s article is less about the database engine to pick, and more about which promises to believe.
Those that are immune to changing circumstances.
Here’s what you can expect in today’s article:
What is Open Source Enclosure
The 3 categories you can choose a money database from
And why durably governed open source is rare (hint: that’s actually the point)
Enough intro, let’s dive in.
