class ActiveRecord::SchemaMigration

def self.create_table(limit=nil)
  unless connection.table_exists?(table_name)
    version_options = {null: false}
    version_options[:limit] = limit if limit
    connection.create_table(table_name, id: false) do |t|
      t.column :version, :string, version_options
    end
    connection.add_index table_name, :version, unique: true, name: index_name
  end
end

def self.drop_table
  if connection.table_exists?(table_name)
    connection.remove_index table_name, name: index_name
    connection.drop_table(table_name)
  end
end

def self.index_name
  "#{Base.table_name_prefix}unique_schema_migrations#{Base.table_name_suffix}"
end

def self.table_name
  "#{Base.table_name_prefix}schema_migrations#{Base.table_name_suffix}"
end

def version
  super.to_i
end