Major Upgrade
Example: PgBouncer 1 -> PgBouncer 2
Currently, the charm supports PgBouncer major version 1 only; therefore, minor upgrades are only possible. Canonical is NOT planning to support in-place upgrades for the Major version change. The new PgBouncer will have to be installed nearby, and the data will be copied from the old to the new installation. After announcing the next PostgreSQL+PgBouncer major versions support, the appropriate manual will be published here.