January 26, 2026 / by Rathish Kumar B
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| Source: Pixabay |
OpenAI recently shared details on how they scale PostgreSQL to power ChatGPT for over 800 million users. When you hear numbers like that, you probably imagine a complex, distributed, sharded database architecture. You might expect them to be using something like Spanner, CockroachDB, or Cassandra.
The reality is surprisingly simple: They use a single Postgres primary with nearly 50 read replicas.
It sounds counter-intuitive. How does a single database node handle traffic for one of the most popular apps in the world? The answer provides a fascinating look at how real-world systems evolve versus how we design them on a whiteboard.