Error "there is no unique constraint matching given keys" migrating DB to latest canvas release

[peter.h...@gmail.com]

I'm trying to upgrade to the latest version of canvas. When I try to run 

RAILS_ENV=production bundle exec rake db:migrate

I get the error:

PG::Error: ERROR:  there is no unique constraint matching given keys for referenced table "quizzes"

: ALTER TABLE "quiz_statistics" ADD CONSTRAINT "quiz_statistics_quiz_id_fk" FOREIGN KEY ("quiz_id") REFERENCES "quizzes"(id)

Anyone got an idea, how to solve this?

Thanks,

Peter

[Cody Cutrer]

Can you post the output of psql with the following command:

\d quizzes

Thanks,

Cody Cutrer

Software Engineer

Instructure

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[peter.h...@gmail.com]

Thanks for your reply.

In the meantime I solved the problem.

1) I removed 

add_foreign_key :quiz_statistics, :quizzes

from

20130508214241_add_quiz_statistics_foreign_key.rb

and did the migration.

2) After that I added the line again and did the update again. It worked fine now. 

Nevertheless if I do

/d I get the output

Did not find any relation named "quizzes".

Is this correct?

[Cody Cutrer]

Peter,

Commenting out that line means that it was never added, and when you re-ran it wasn't added either, cause the migration had already been run. I'm not sure why your \d didn't find the quizzes table (likely because you were using a different user and it wasn't using the correct schema search_path). Anyways, you're probably okay. The foreign key is just extra protection around bad data getting into the database, but the app should never try to put bad data in in the first place. We monitor database errors here at Instructure, and haven't seen anything try to violate that constraint in our environment, so I wouldn't worry about it if I was you.

Cody Cutrer

Software Engineer

Instructure