Ruby on rails 超表迁移导致rails 2.3.8出现问题

我正在使用HyperRecord前端的Hypertable db。我在里面修复了一些bug。但现在迁移让我陷入困境。每次迁移时，都会显示错误：

rake aborted!
undefined method `select_rows' for #<ActiveRecord::ConnectionAdapters::HypertableAdapter:0xb6f791c4>
.rvm/gems/ruby-1.8.7-p352@r2.3.8/gems/activerecord-2.3.8/lib/active_record/connection_adapters/abstract/database_statements.rb:27:in `select_values'

rake aborted!
You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.map
/.rvm/gems/ruby-1.8.7-p352@r2.3.8/gems/activerecord-2.3.8/lib/active_record/migration.rb:421:in `get_all_versions'

我试图通过在初始化中添加修复来删除这些函数

module ActiveRecord
  module ConnectionAdapters
    class HypertableAdapter

      def select_rows(sql, name = nil)
      end
    end
  end
end

然后在接受数组或散列时出现错误Nil值。为了修复它，我在修复代码中添加了新方法

module ActiveRecord
  module ConnectionAdapters
    class HypertableAdapter

      def select_rows(sql, name = nil)
      end

      def select_values(sql, name = nil)
        result = select_rows(sql, name)
        result.map { |v| v[0] } unless result.nil?
      end
    end
  end
end

然后出现了错误：

rake aborted!
undefined method `select_rows' for #<ActiveRecord::ConnectionAdapters::HypertableAdapter:0xb6f791c4>
.rvm/gems/ruby-1.8.7-p352@r2.3.8/gems/activerecord-2.3.8/lib/active_record/connection_adapters/abstract/database_statements.rb:27:in `select_values'

rake aborted!
You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.map
/.rvm/gems/ruby-1.8.7-p352@r2.3.8/gems/activerecord-2.3.8/lib/active_record/migration.rb:421:in `get_all_versions'

---

有人知道这是怎么回事吗？

这段代码删除了所有错误。但现在迁移运行良好，但不会回滚

module ActiveRecord
  module ConnectionAdapters
    class HypertableAdapter

      def select_rows(sql, name = nil)
        result = execute(sql)
        rows = []
        result.cells.each { |row| rows << row }
        rows
      end

      def select_values(sql, name = nil)
        result = select_rows(sql, name)
        result.map { |v| v[0] } unless result.nil?
      end
    end
  end
end

---

此修复程序非常适合向上迁移和活动记录模型。唯一剩下的就是迁移回滚。