Beyond Safe Migrations: Better Practices for Ecto + PostgreSQL - Joe Harrow | ElixirConf US

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Beyond Safe Migrations: Better Practices for Ecto + PostgreSQL - Joe Harrow | ElixirConf US 2025

Beyond Safe Migrations: Better Practices for Ecto + PostgreSQL - Joe Harrow | ElixirConf US 2025

This talk was recorded at ElixirConf US 2025. If you’re curious about our upcoming event, check https://elixirconf.com✨
Database migrations can look safe—tests pass, the code deploys, and the migration runs without error. But as I’ve discovered the hard way, “safe” ain’t easy. In this talk, I’ll explore the subtle (and sometimes catastrophic) ways seemingly safe migrations can impact production systems, especially in high-traffic Elixir applications backed by PostgreSQL.
Drawing from real-world experience at Cars.com, I’ll share what’s gone wrong, what we’ve learned, and how we’ve evolved our processes to make migrations safer in practice. Topics will include common Ecto migration pitfalls, how PostgreSQL’s locking behavior can catch teams off-guard, and how to use CI checks, strategies, and custom tooling to build a migration culture that’s both cautious and fast-moving.
This talk is especially geared toward teams managing live production databases but will be valuable to any Elixir developer who’s ever had to run mix ecto.migrate with crossed fingers.

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