To make database downgrade works in nova, we need review and approval on
the following change:
https://review.openstack.org/3891
I hope, there is some number of kind people who can give me some +1s or
comments on them.
The rational behind this patch is:
1.Make data(metadat, table and column definition) local to
upgrade/downgrade function,
so sqlalchemy-migrate python script load engine will not get the wrong
state and generate fault.
Related code:
http://code.google.com/p/sqlalchemy-migrate/source/browse/migrate/versioning/script/py.py#121
2.Add sql scripts to work around various bugs in
sqlalchemy/sqlalchemy-migrate to keep
compatibility with various versions of them.
Related issue:
http://code.google.com/p/sqlalchemy-migrate/issues/detail?id=143
http://code.google.com/p/sqlalchemy-migrate/issues/detail?id=94
http://code.google.com/p/sqlalchemy-migrate/issues/detail?id=72
3.Use sqlalchemy reflelction to reduce code lines and avoid change of
the existing code in the future.
4.Add snake walk test case to assure the upgrade/downgrade works in some
sense.
Currently, this patch has been tested with the following version
combinations
of sqlalchemy/sqlalchemy-migrate on fedora 16 and ubuntu precise for
sqlite in memory,
sqlite persistence, mysql, postgresql engines:
sqlalchemy-migrate==0.6.1
sqlalchemy==0.6.8
sqlalchemy-migrate==0.7.2
sqlalchemy==0.7.5
sqlalchemy-migrate==0.7.1
sqlalchemy==0.6.8
Since sqlalchemy-migrate 0.6.x is not aware of sqlalchemy 0.7.x changes,
the combination is invalid.
Best Regards, Hengqing Hu
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