AWS DMS 'serverless' migration eats foreign keys alive, turns simple mysql move into multi-hour schema resurrection ritual

A recent database migration project undertaken by a developer to transfer a MySQL database from DigitalOcean's managed service to Amazon Web Services' (AWS) RDS encountered significant challenges. The migration, which was initially attempted using AWS Database Migration Service (DMS) in serverless mode, was hindered by complex networking configurations. After switching to a traditional EC2-based replication instance, the developer successfully created a migration task, but subsequently discovered that DMS had not preserved the database's structural integrity, resulting in missing foreign keys and primary keys. The issue was resolved by manually dumping and restoring the schema before re-running the migration with updated endpoint settings. The experience highlighted the importance of premigration checks and the limitations of DMS in preserving database objects during migration. The project's outcome has significant implications for businesses planning similar migrations, emphasizing the need for careful planning and attention to detail when using DMS to ensure a successful transfer of critical data.