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Squasher compresses old migrations in a Rails application. If you work on a big project with lots of migrations, everyrake db:migrate might take a few seconds, or creating of a new database might take a few minutes. That's because Rails loads all those migration files. Squasher removes all the migrations and creates a single migration with the final database state of the specified date (the new migration will look like a schema).

You should not add this to your Gemfile. Just standalone installation:

$ gem install squasher

@note if you use Rbenv don't forget to runrbenv rehash.

@note stop all preloading systems if there are present (spring, zeus, etc)

Suppose your application was created a few years ago.%app_root%/db/migrate folder looks like this:

2009...._first_migration.rb2009...._another_migration.rb# and a lot of other files2011...._adding_model_foo.rb# few years later2013...._removing_model_foo.rb# and so on

Storing these atomic changes over time is painful and useless. It's time to archive all this stuff. Once you install the gem you can run thesquasher command.

$ squasher 2014 #compress all migrations which were created prior to the year 2014

You can tellsquasher a more detailed date, for example:

$ squasher 2013/12    #prior to December 2013$ squasher 2013/12/19 #prior to 19 December 2013

-d - execute indry mode - test a squashing process without deleting old migrations. The final output will beprinted in the console.

-r - reuse a database from previous squashing process. The option can be used in the next cases:

• you've run squasher indry mode before and there were no errors
• you're squashing migrations gradually. For example, you want to squash migrations from 2013 till 2015, but theprocess breaks in a migration from 2014. In this situation you squash till 2014, save the squasher'sdatabase at the end, make a patch in the broken migration and run again the suite with-r option. As the resultsquasher will not need to create the db schema and all data from the previous migrations will be there.

It works and was tested on Ruby 2.0+ and Rails 3.1+. It also requires a valid configuration inconfig/database.yml and using Ruby format indb/schema.rb (default Rails use-case).If an old migration inserted data (created ActiveRecord model records) you will lose this code in the squashed migration,BUTsquasher will ask you to leave a tmp database which will have all data that was inserted while migrating. Using this database you could add that data as another migration, or intoconfig/seed.rb (the expected place for this stuff).

• 0.2.0
  • adddry mode and ability to reuse the previous squasher database
  • improve database config processing
  • raise the minimum supported version of Ruby
• 0.1.7
  • a regression fix of the log output (@lime)
  • improve a multi-platform support (@johncarney)
• 0.1.6
  • support multiple database settings (@ppworks)

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request