MySQL

Codex struggles with connecting to external APIs and databases, which is critical for backend development. The GitHub-centric design limits flexibility for developers using other version control systems or task management tools like Monday or Google Sheets.

Migrating large datasets from relational databases (e.g., MySQL) to MongoDB is difficult and time-consuming, requiring significant engineering effort to restructure data and handle schema differences.

Fly.io does not provide built-in managed Redis or MySQL services, requiring developers to provision and manage databases separately or use external providers.