Does rake db:schema:dump recreate schema.rb from migrations or the database itself?
The answer is simple: from the database.
By the way - when you take a look into the source code of db:* tasks you can see that migration tasks calls schema:dump after the run
desc "Migrate the database (options: VERSION=x, VERBOSE=false)."task :migrate => :environment do ActiveRecord::Migration.verbose = ENV["VERBOSE"] ? ENV["VERBOSE"] == "true" : true ActiveRecord::Migrator.migrate("db/migrate/", ENV["VERSION"] ? ENV["VERSION"].to_i : nil) Rake::Task["db:schema:dump"].invoke if ActiveRecord::Base.schema_format == :rubyendSo the migration works in the way that it change the database and then generate schema.rb file.