The "Bus Factor" Risk in MongoDB, MariaDB, Redis, MySQL, PostgreSQL, and SQLite

Ever wonder what would happen to an open source database project in case its main developers "get hit by a bus"? Or, less dramatically, if they leave the project completely. That's what the "bus factor" (also called "truck factor") measures: how many people would have to disappear before no one left knows how to fix or update specific parts of the code. The Bus Factor Ranking I’ve been messing around with a tool called the Bus Factor Explorer by JetBrains to explore the associated risk in some of the most popular open source databases. I looked at six of the big ones to see where they stand. Here’s the current baseline (March 2026) according to this tool: