Question

So my Mac went down and now trying to build my project on my new Mac. I need to know when running rake db:migrate does it look at the schema.rb file?

As I am getting

Mysql::Error: Table 'myproject_development.users' doesn't exist: SHOW FIELDS FROM `users`

Even when I run rake db:migrate:up VERSION=001 which has no reference to users I get the same error?

If it matters my migrations start like

001_...
002_...
003_...
20100222171241_...

Answer 1

The migration code generally doesn’t look at the schema file. It looks at the names of all the migration files and the database table called schema_migrations, and determines which migrations haven’t been run yet. (I believe it does dump the schema at the end of running migrations.) Either your missing a migration, or your schema_migrations table is out of sync with your database.

After making a backup, you can start to troubleshoot. Do you have a migration that creates the users table? If not, where did it go? If you have it, why isn’t it running?

FYI The migrations that start with numbers (eg. 001) are older versions of migrations. Sometime around 2.2 or 2.3 the names of the migrations were changed to dates, which is what you are seeing in the later migrations.

There may be a problem with the way those first few migrations are named, and they are not being found (I can’t remember the migration story when this naming scheme switched). And maybe it tracked the migrations differently back then so there may be some futzing to make it work with the more modern scheme. You can fairly safely rename them following the new scheme, using the datestamp of the file.

Hope this helps.