This patch allows disable ddl transactions in Rails 3.2

migrator_monkey_patch.rb

class ActiveRecord::Migrator
  def migrate(&block)
    current = migrations.detect { |m| m.version == current_version }
    target = migrations.detect { |m| m.version == @target_version }

    if target.nil? && @target_version && @target_version > 0
      raise UnknownMigrationVersionError.new(@target_version)
    end

    start = up? ? 0 : (migrations.index(current) || 0)
    finish = migrations.index(target) || migrations.size - 1
    runnable = migrations[start..finish]

    # skip the last migration if we're headed down, but not ALL the way down
    runnable.pop if down? && target

    ran = []
    runnable.each do |migration|
      if block && !block.call(migration)
        next
      end

      ActiveRecord::Base.logger.info "Migrating to #{migration.name} (#{migration.version})" if ActiveRecord::Base.logger

      seen = migrated.include?(migration.version.to_i)
      # On our way up, we skip migrating the ones we've already migrated
      next if up? && seen

      # On our way down, we skip reverting the ones we've never migrated
      if down? && !seen
        migration.announce 'never migrated, skipping'; migration.write
        next
      end

      begin
        migrate = Proc.new do
          migration.migrate(@direction)
          record_version_state_after_migrating(migration.version)
        end

        if Settings.migrations_without_transaction.include?(migration.name)
          migrate.call
        else
          ddl_transaction do
            migrate.call
          end
        end
        ran << migration
      rescue => e
        canceled_msg = ActiveRecord::Base.connection.supports_ddl_transactions?  ?  "this and " : ""
        raise StandardError, "An error has occurred, #{canceled_msg}all later migrations canceled:\n\n#{e}", e.backtrace
      end
      ran
    end
  end
end