Corona Warn App Server uses Flyway for database version control. Flyway is an open source
database migration tool. It updates the database from one version to the next using migrations.
The migration scripts are written in plain SQL with database specific syntax which in this case is PostgreSQL and are located in the db
directory under common/persistence/src/main/resources.
The migrations can either be versioned or repeatable. The former has a unique version and is applied exactly once. The latter does not have a version and instead, they are (re-) applied every time their checksum changes. For a single migration, all statements are run within a single database transaction.
The naming convention of the versioning scripts is <Prefix><Version>__<Description>.sql. The default prefix is V.
An appropriate example for a migration script is V1_createUserTable.sql.
For more details see
Flyway SQL-based Migrations.
The external Flyway configuration is located in the application.yaml file of each service it's
prefixed with spring.flyway. See data migration properties
for detailed information.
In a first step, the diagnosis key distribution application ensures that the database does not store diagnosis keys for
longer than a maximum of 14 days. Therefore, the RetentionPolicy runner deletes any diagnosis keys that do not have a
submissionTimestamp greater or equal to the respective threshold. Analogously, it removes any files from the object
store which are associated with points in time earlier than 14 days ago.
The number of days can be configured in application.yaml
by using the property retention-days.