CODEWITHSUNDEEP
ruby-on-railspostgresqlrails-migrations
Piotr Brudny
Piotr Brudny

Reputation: 656

How to skip rails migrations after creating database from dump

I restored my database from the latest dump and tried to run rake tests. Unfortunately 30 migrations were pending. My first idea was to comment out each of 30 migrations code and run 'rake db:migrate' but there must be a simpler solution. I use Rails 2.3.14 and Postgresql 9.1.3.

Upvotes: 6

Views: 4391

Answers (3)

Kjell
Kjell

Reputation: 582

You could also manually add the timestamps of the missing migrations in the db table like:

INSERT INTO "public"."schema_migrations"("version") VALUES ('20201212012345')

That should have the same effect as temporarily outcommenting the 'create' instructions in the migration files. If you run migrations as part of a deploy process from git, commenting out would mean you had to push those changes to git.

If you just work on staging / development env, directly fixing the db might be nicer than pushing those changes, possibly confusing other deploys or devs.

Upvotes: 0

Marlin Pierce
Marlin Pierce

Reputation: 10099

Kevin is correct. However, he is missing a critical point.

When you restore from a backup it restores the schema_migrations table which tracks which migrations need to be run. If those thirty migrations had been run on the database you restored from, they would not have run.

However, your code is thirty migrations ahead of the snapshot of your database represented by the backup.

This can happen to me if I deploy, then grab the production backup right away. Although the migrations have run on production, I'm getting the backup from before office hours prior to my deployment. I usually like to wait a day and get the next day's backup.

Or, don't worry about it. Your backup is before those thirty migrations, but then they were applied, so the migrations have made sure your schema matches the version of your code. That's a good thing.

Don't sweat it, and refresh again tomorrow, when the backup has your changes.

Upvotes: 4

Kevin Bedell
Kevin Bedell

Reputation: 13424

If you're restoring a database from a dump, the schema_migrations table should restore along with the rest of the tables.

This seems to indicate your schema_migrations table may not be getting backed up which would lead to the problem you have now.

The ideal solution would be to restore a backup that has all the tables in it correctly -- including schema_migrations.

Even if you decide to find a way around this in the short-term, in the long-term the correct solution is to modify your backup scripts to get all the tables you need, including schema_migrations.

In terms of what to do now, the ideal solution is probaby to backup just that one table (schema_migrations) from your database and import that data into the database you're trying to load now. Then your migrations should no longer be pending.

Doing that with a simple table dump and load script should be fine. The simple postgres gui PgAdmin ( http://www.pgadmin.org/ ) may also provide some basic tools for dumping then loading a single table.

Upvotes: 7

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