keystone/releasenotes/notes/switch-to-alembic-1fa5248f0...

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YAML

---
upgrade:
- |
The database migration engine has changed from `sqlalchemy-migrate`__ to
`alembic`__. For most deployments, this should have minimal to no impact
and the switch should be mostly transparent. The main user-facing impact is
the change in schema versioning. While sqlalchemy-migrate used a linear,
integer-based versioning scheme, which required placeholder migrations to
allow for potential migration backports, alembic uses a distributed version
control-like schema where a migration's ancestor is encoded in the file and
branches are possible. The alembic migration files therefore use a
arbitrary UUID-like naming scheme and the ``keystone-manage db_version``
command returns such a version.
When the ``keystone-manage db_sync`` command is run without options or
with the ``--expand`` or ``--contract`` options, all remaining
sqlalchemy-migrate-based migrations will be automatically applied.
Data migrations are now included in the expand phase and the ``--migrate``
option is now a no-op. It may be removed in a future release.
.. __: https://sqlalchemy-migrate.readthedocs.io/en/latest/
.. __: https://alembic.sqlalchemy.org/en/latest/