alembic stuck on database upgrade

See original GitHub issue

I’m running a database migration, and Alembic complains with alembic.util.CommandError: Target database is not up to date.

So and I then run a database upgrade python manage.py db upgrade

Here is the output: INFO [alembic.migration] Context impl PostgresqlImpl. INFO [alembic.migration] Will assume transactional DDL. INFO [alembic.migration] Running upgrade 604497a5e5 -> 431e33e6fce, empty message

The issue is that Alembic never finishes the upgrade (never quits the terminal) and it appears stuck on the third step, I have tried severally, even leaving it for several minutes but it never completes the upgrade. I have tried running this locally and on the server and it doesn’t work (it’s not an issue with the connection).

Issue Analytics

State:
Created 9 years ago
Comments:12

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jwindridgecommented, Jul 29, 2015

Thanks for the reply - worked it out in the end: I had a database session open in a flask shell, which was preventing alembic from obtaining a lock and therefore running the update - finished the session and then the migration worked fine.

3reactions

kangju1commented, Aug 19, 2019

For those who want to run alembic upgrade when app is running, add the following code in your project’s app file.

@app.teardown_appcontext
    def shutdown_session(exception=None):
        db.remove()

the variable db is the database session from your database setting file. so you should import it first. you have to remove the session (return it to the pool) after each request.

When alembic runs, it uses flask’s app context, and the currently running app is holding all connections, which means there are no available connections for alembic to use.

https://flask.palletsprojects.com/en/1.0.x/appcontext/