django.db.utils.ProgrammingError: relation already exists

Question

I\'m trying to set up the tables for a new django project (that is, the tables do NOT already exist in the database); the django version is 1.7 and the db back end is Postgr

Answer 1

Django provides a --fake-initial option which I found effective for my use. From the Django Migration Documentation:

--fake-initial

Allows Django to skip an app’s initial migration if all database tables with the names of all models created by all CreateModel operations in that migration already exist. This option is intended for use when first running migrations against a database that preexisted the use of migrations. This option does not, however, check for matching database schema beyond matching table names and so is only safe to use if you are confident that your existing schema matches what is recorded in your initial migration.

For my use, I had just pulled a project from version control and was preparing to add some new model fields. I added the fields, ran ./manage.py makemigrations and then attempted to run ./manage.py migrate which threw the error since, as one would expect, many of the fields already existed in the existing database.

What I should have done was to run makemigrations immediately after pulling the project from versions control to create a snapshot of existing models' state. Then, running the ./manage.py migrate --fake-initial would be the next step.

After that you can add away and makemigrations > migrate as normal.

NOTE: I do not know if a --fake-initial would skip existing fields and add new ones. I opted to comment out the new fields I'd created up to that point, run the --fake-initial as if it were the first thing I did after pulling from version control, then added in updated fields in the next migration.

Other related documentation: https://docs.djangoproject.com/en/dev/topics/migrations/#initial-migrations