Hi, I have a use case where I have two databases, each of which provides a subset of my models. I have two seperate __abstract__ base classes (each with its own metadata) that each model inherits from to determine on which database they belong. To manage separate migrations on each, I will most likely need 2 separate directories with alembic "versions".
What's the best way to manage this situation with migrations? If I recognize my two databases as "main" and "staging", I would want to invoke any alembic command with an additional argument, such as alembic upgrade/current/.. --target_db staging that will take care of everything else (i.e. point to the right "versions" directory, use the right database url, etc.) I see a couple of candidates to achieve this but I am not sure which is a dead end: 1. Use the "multiple bases" feature (http://alembic.readthedocs.org/en/latest/branches.html#working-with-multiple-bases) As long as I create the right labelled branches, this looks like it can easily substitute the command above with the following alembic upgrade --head=staging@head I would have to make a mapping of "branch labels" to database urls/engines inside the env.py, and then determine the right engine from the targeted head. However, at first glance I cannot get a hold of the targeted head from the context information available in there. 2. Use the "multidb" template. While the name of it sounds promising, this is so sparsely documented that I wouldn't know where to start. 3. Use the "-x" argument feature to implement my target db. This looks straightforward, especially with the example here (http://alembic.readthedocs.org/en/latest/api.html#alembic.environment.EnvironmentContext.get_x_argument). However how can I combine it with a seperate "versions" directory? I want to avoid having to specify both alembic upgrade --head=staging@head -x target_db=staging 4. Use two totally seperate alembic.ini and alembic directories. That looks like the simplest way out. Any feedback is welcome. Dimitris -- You received this message because you are subscribed to the Google Groups "sqlalchemy-alembic" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy-alembic+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
