If you've ever tried converting a MySQL database to PostgreSQL (or the reverse), you've probably run into tools that do text replacement on your SQL dump. They work fine — until they don't. Where regex converters fail The edge cases pile up fast: Zero dates ( 0000-00-00 ) — PostgreSQL rejects them outright AUTO_INCREMENT — needs to become a proper sequence with the counter set to the right value ENUM columns — most tools skip them or flatten to VARCHAR Ba...