django db migration failed with postgres

There is another way. Since you know the last id value in django_migrations table, say it is 100. Then, you need to do this:

ALTER SEQUENCE django_migrations_id_seq RESTART WITH 101;

I overlooked the name of the 'django_migrations_pkey' column and I didn't realize that was in the database. Somehow django was one step behind the actual database and trying to use the primary key (pk=27) instead of the number it was actually on (which should have been 28)

I was unsure about how to change this from within django so instead I just deleted the last column from the database so it was one primary key shorter and on track with django and it started working just fine.

I got this error after I had previously manually tinkered with the django migrations tables entries (after some previously dodgy migrations were added then removed).

This left the django_migrations IDs out of order (so to speak) with the default position of the entry in the django_migrations table.

The issue is that django takes the ID of the last entry and +1 to create a new entry (in table below: 197 + 1 = 198), however as you can see Key (id)=(198) already exists in the table.

187 | foo_app             | 0016_auto_20161220_2332                     | 2017-01-06 05:22:07.666172+00
198 | bar_app             | 0004_auto_20160423_2122                     | 2017-01-13 05:38:31.922738+00
197 | baz_app             | 0013_auto_20170203_2311                     | 2017-02-08 18:50:22.70143+00

As you can see the numbers for the primary key on the left are out of order. What I did was manually delete the out of order entries in the django_migration then re-add them.

DELETE from django_migrations where name = '0004_auto_20160423_2122';
DELETE from django_migrations where name = '0013_auto_20170203_2311';

INSERT INTO django_migrations VALUES (188, 'baz_app', '0013_auto_20170203_2311', date());
INSERT INTO django_migrations VALUES (189, 'bar_app', '0004_auto_20160423_2122', date());

Also of note is that the migration that I was initially trying to add 'new_app, '0002_auto_00000000_1111' actually modified the new_app table in postgres, however the django_migrations table didn't get updated.

So the second time I tried to re-run the migration 0002_auto_00000000_1111 I got the error:

django.db.utils.ProgrammingError: column "new_app_field" of relation "new_app_new" already exists

My solution above fixed the problem for me.