Implementing CSV Export in Elixir with NimbleCSV

Dan Schultzer provides a guide on exporting CSV files using the NimbleCSV library in Elixir. He begins by demonstrating a naive implementation involving streaming data from a database and setting up the controller action for CSV export. He highlights pitfalls, such as the 'greediness' of `Enum.map/2`, which loads all data into memory rather than streaming it chunk by chunk. Instead, he proposes using `Stream.each/2` or `Stream.transform/3` for a more efficient approach. Schultzer encountered timeouts with larger datasets, which he resolved by moving away from transactions and implementing cursor pagination to avoid database connection timeouts. He also faced issues with Cowboy's `idle_timeout` setting, which he circumvented by migrating to the Bandit server library. Lastly, he touches on future considerations, such as offloading the process to a background task and utilizing static content hosting services, as well as potential parallelization of row transformations. His article is packed with code snippets and practical advice for optimizing CSV exports in Elixir applications.