Heroku is missing the last 4 migrations for a RoR app. The files exist in the git repository and are named/numbered accordingly. I tried manually forcing that version to run, but it simply can't find it. I tried this:
heroku run rake db:migrate:up VERSION=20190328183515
and the result was
ActiveRecord::UnknownMigrationVersionError: No migration with version number 20190328183515
Trying to redeploy from local to heroku stage does nothing since it states everything is up to date. I tried touching the files in case they weren't included in the deployed files, but looking at the git repository confirmed that's not the case.
Any ideas on what's going on here and how to get heroku to recognize that it is missing 4 migration files that still need to be processed? Resetting the database is not an option. I tried rolling back the database and running the migrations again but it stops on the migration file for 3/27/2019
My understanding is that whoever created the migrations should've also updated schema.rb. Since I've pulled the migrations, I should've also pulled the updated schema.rb. However, once in a while, schema.rb updates after I run bundle exec rake db:migrate.
My current workflow is:
git pull --rebase origin master --prune
rails s
Rails tells me to migrate
bundle exec rake db:migrate
Realize schema.rb updated
At this point, I'm pretty sure I'm not supposed to check in the updated schema.rb. I'd manually revert it through git checkout origin/master db/schema.rb.
So what went wrong in this case? Did a co-worker forget to run migrations after creating them? Did I do something wrong?
As far as I know schema can change after running rails db:migrate because of:
A co-worker did not commit the schema.rb so when you fetched and run the migrations you get the diff
A different DB version is running on your local machine. Based on db configuration schema may be changed accordingly.
Running git diff will help you to understand what is going.
schema.rb retains two key sets of data:
a description of all the tables in your app database structure
a list of all the migrations that have been applied.
if a new developer were to join your team, they should be able to run rake db:schema:load and get an up-to-date database structure straight away. That's far more efficient and reliable than expecting them to run through all the migrations manually.
Running rake db:migrate, even if there are no outstanding migrations that need running, will always regenerate db/schema.rb. Most of the time you won't notice because the file will be the same – but you may get differences in whitespace formatting or column order.
The best practice (IMHO) should always be to check in the updated db/schema.rb in the same commit as any migrations you've added.
When fetching or pulling branches to your local machine, running rake db:migrate will apply whatever new migrations need to be run based on the records in your local database's schema_migrations table. After that, your new db/schema.rb should be the same as the one you pulled down – but if it isn't, git diff will show you what the difference is.
You can then make a judgement call as to what the best course of action is. If the only difference is cosmetic, I personally tend to revert the unstaged changes and leave the committed version untouched until the next migration.
All the above also applies if you have switched to a SQL-based structure file (db/structure.sql) by specifying config.active_record.schema_format = :sql in config/application.rb.
Ok, I have stuffed up my migrations. I tried to sort it by deleting duplicates, sorting the schema.rb etc but I don't think I have done it properly.
When I try to deploy to heroku, or rather heroku run rake db:migrate, I get
Multiple migrations have the version number 20130307005437
The migrate works fine on localhost but not heroku.
Unfortunately when I look for migration no 20130307005437, it's not there in my db/migrate.
How can I find it to sort the problem?
While this file might not be visible within your directory listing, I suspect that there might already be a file within your Git repository, which is what is causing this error from appearing on Heroku and not locally.
Please ensure that you've only got one migration inside that Git repo with that number.
In the past (without Heroku), I've deleted my migration files once I've run them and don't expect to roll back. However, I've noticed that Heroku likes to run every migration every time I run
heroku run rake db:migrate
Is it going to get upset if I remove the files?
I don't want to add schema.rb to .gitignore, because I want to be able to load a new database schema from that file. However, keeping it checked in is causing all sorts of spurious conflicts that are easily resolved by a fresh db:migrate:reset.
Basically I want a way to:
Keep schema.rb in the repository for deploy-time database setup
Keep schema.rb in '.gitignore' for general development
There would be one or two people responsible for updating schema.rb and knowing that it was correct.
Is there a way I can have my cake and eat it, too?
I'm afraid the magic solution you're looking for does not exist. This file is normally managed in version control, then for any conflicts on the version line just choose the later of the two dates. As long as you're also running all of the associated migrations nothing should get out of sync this way. If two developers have caused modifications to a similar area of schema.rb and you get conflicts in addition to the version then you are faced with a normal merge conflict resolution, but in my opinion these are normally easy to understand and resolve. I hope this helps some!
One other thing you can do is use:
git update-index --assume-unchanged /path/schema.rb
This will keep the file in the repository but won't track changes. you can switch the tracking anytime by using:
git update-index --no-assume-unchanged /path/schema.rb
What has worked really well for me is to delete and .gitignore schema.rb and then have it regenerated for each developer when they rake db:migrate.
You can still achieve what you wanted without migrating from 0 and risking broken migrations from years ago by simply doing a "roll-up" of the migrations periodically. You can do this by:
Run all outstanding migrations with rake db:migrate
Taking the contents of your schema.rb in the ActiveRecord::Schema.define block
Paste it into your initial_schema migration inside def up (overwriting what's already there)
Delete all other migrations
Now your initial_schema migration is your starting point for new systems and you don't have to worry about conflicts in schema.rb that may not be resolved correctly. It's not magical, but it works.
Would it be sufficient to do a rake db:dump in a pre-commit git hook?
The following won't necessarily fix (1) or (2), but it might take care of the merging issue, and then maybe (1) and (2) go away.
Instead of using .gitignore, use separate branches: Develop which omits schema.rb and Test and Deploy which include schema.rb. Only make code changes in the Develop branches and never merge from Test into Develop. Keep schema.rb in a separate branch:
Developer A
Develop --------
Local Schema \ Your Repo
Test ---------> Dev A
---------> Dev B
Developer B / Master
Develop -------- Schema
Local Schema Test
Test Deploy
In Git, branches are pointers to collections of file contents, so they can include or exclude particular files as well as track file versions. This makes them flexible tools for building your particular workflow.
You could define a merge strategy.
I've found this solution, but dont remember the source
[merge "railsschema"]
name = newer Rails schema version
driver = "ruby -e '\n\
system %(git), %(merge-file), %(--marker-size=%L), %(%A), %(%O), %(%B)\n\
b = File.read(%(%A))\n\
b.sub!(/^<+ .*\\nActiveRecord::Schema\\.define.:version => (\\d+). do\\n=+\\nActiveRecord::Schema\\.define.:version => (\\d+). do\\n>+ .*/) do\n\
%(ActiveRecord::Schema.define(:version => #{[$1, $2].max}) do)\n\
end\n\
File.open(%(%A), %(w)) {|f| f.write(b)}\n\
exit 1 if b.include?(%(<)*%L)'"
put this "somewhere" and
git-config --global core.attributesfile "somewhere"
I built a gem to solve this problem.
It sorts columns, index names and foreign keys, removes excess whitespace and runs Rubocop for some formatting to unify the output of your schema.rb file.
https://github.com/jakeonrails/fix-db-schema-conflicts
After you add it to your Gemfile you just run rake db:migrate or rake db:schema:dump like normal.
Commit schema.rb file.
Run git pull (or continue with what you're doing)
Every time you migrate the database, the schema.rb file updates and appears in git status. When working on something and occasionally doing git pull, this can be annoying because you have to commit schema.rb file before pulling to resolve conflict. This means that every time you migrate the database, you need to commit schema.rb file.
schema.rb should be tracked Git, of course.
I've just released this gem that can solve an issue with "conflicts" between branches for good.
The idea of that gem is simple. It keeps all migrated migrations inside tmp folder so that Git ignores them. It's just only your local story. These files are needed to roll back the "unknown" migrations being in another branch. Now, whenever you have an inconsistent DB schema due to running migrations in some other branch just run rails db:migrate inside the current branch and it will fix the issue automatically. The gem does all this magic automatically for you.