Making changes to the database

Making changes to the database

In order to make a change to the mogan database you must update the database models and then create a migration to reflect that change.

There are two ways to create a migration which are described below, both of these generate a new migration file. In this file there is only one function:

  • upgrade - The function to run when
    mogan-dbsync upgrade is run, and should be populated with code to bring the database up to its new state from the state it was in after the last migration.

For further information on creating a migration, refer to Create a Migration Script from the alembic documentation.


This is the simplest way to create a migration. Alembic will compare the models to an up to date database, and then attempt to write a migration based on the differences. This should generate correct migrations in most cases however there are some cases when it can not detect some changes and may require manual modification, see What does Autogenerate Detect (and what does it not detect?) from the alembic documentation.

mogan-dbsync upgrade
mogan-dbsync revision -m "A short description" --autogenerate


This will generate an empty migration file, with the correct revision information already included. However the upgrade function is left empty and must be manually populated in order to perform the correct actions on the database:

mogan-dbsync revision -m "A short description"
Creative Commons Attribution 3.0 License

Except where otherwise noted, this document is licensed under Creative Commons Attribution 3.0 License. See all OpenStack Legal Documents.