diff --git a/releasenotes/notes/alembic-migrations-902b31edae7a5d7d.yaml b/releasenotes/notes/alembic-migrations-902b31edae7a5d7d.yaml new file mode 100644 index 00000000..27e05949 --- /dev/null +++ b/releasenotes/notes/alembic-migrations-902b31edae7a5d7d.yaml @@ -0,0 +1,38 @@ +--- +prelude: > + - **Experimental** zero-downtime database upgrade using an + expand-migrate-contract series of operations is available. +upgrade: + - | + The database migration engine used by Glance for database upgrades has been + changed from *SQLAlchemy Migrate* to *Alembic* in this release. + + * This has necessitated a change in the location and naming convention for + migration scripts. Developers, operators, and DevOps are strongly + encouraged to read through the `Database Management`_ section of the + Glance documentation for details of the changes introduced in the Ocata + release. Here's a brief summary of the changes: + + - All the ``glance manage db`` commands are changed appropriately to use + Alembic to perform operations such as ``version``, ``upgrade``, + ``sync`` and ``version_control``. Hence, the "old-style" migration + scripts will no longer work with the Ocata glance manage db commands. + + - Database versions are no longer numerical. Instead, they are the + *revision ID* of the last migration applied on the database. + + * For example, the Liberty migration, which was version ``42`` under + the old system, will now appear as ``liberty``. The Mitaka + migrations ``43`` and ``44`` appear as ``mitaka01`` and ``mitaka02``, + respectively. + + * The change in migration engine has been undertaken in order to enable + zero-downtime database upgrades, which are part of the effort to + implement rolling upgrades for Glance (scheduled for the Pike release). + + - A preview of zero-downtime database upgrades is available in this + release, but it is **experimental** and **not supported for production + systems**. Please consult the `Database Management`_ section of the + Glance documentation for details. + + .. _`Database Management`: http://docs.openstack.org/developer/glance/db.html