Streaming Large CSV Exports in Laravel to Avoid Out-of-Memory Failures

A Laravel export feature failed silently for high-volume accounts because it loaded every matching order into memory and built the entire CSV as one string. The author explains that this approach causes memory exhaustion from Eloquent hydration, the growing string, and the response buffer, and also produces malformed output when fields contain commas. The proposed fix uses Laravel's streamDownload to write rows directly to the output as they are produced, so the full file never sits in memory. Input should be streamed as well, with lazyById() recommended for its key-based paging and eager-loading support. Explicit fputcsv arguments are advised to keep output RFC 4180 compliant and avoid PHP 8.4 deprecation warnings.