The SQLx library will run compile time checks to make sure our SQL queries are valid. This is done by running PostgreSQL queries during compile time. Therefore, it is important that DATABASE_URL must be properly set.
- Online mode is when the database is up and running and therefore,
SQLxcan perform compile time SQL queries check against it. - Offline mode is when the database is NOT up and running. But we can save query metadata for offline usage and build to let the app run without SQLx complaining.