Alembic migrations
******************

Each time you make changes to database structure you should also
change the associated history tables. When you make changes to your
models SQLAlchemy-Continuum automatically alters the history model
definitions, hence you can use *alembic revision --autogenerate* just
like before. You just need to make sure *make_versioned* function gets
called before alembic gathers all your models and *configure_mappers*
is called afterwards.

Pay close attention when dropping or moving data from parent tables
and reflecting these changes to history tables.


Troubleshooting
===============

If alembic didn't detect any changes or generates reversed migration
(tries to remove **_version* tables from database instead of
creating), make sure that *configure_mappers* was called by alembic
command.
