rails代码优化，反面例子

现象就是报警总数多的时候，页面打开要很长时间
有问题的代码如下：

module Service
  class UrlProfile; end
  
  class << UrlProfile
    
    def search_followers options, index
      options = inner_option_convert options
      Following::search_followers options, index
    end
    
    def search_alerts options, index
      options = inner_option_convert options
      sort_by = case options[:sort_by]
              when 'type' : 'category asc'
              else 'created_at desc'
              end
      condition= { "index_id" => index.id } 
      condition["category"] = options[:filter] unless options[:filter].blank? or options[:filter] == 'all'
      alert_list = Alert::Alert.all( :conditions => condition, :order=> sort_by )
      alert_list.paginate( options )        
    end
    
    private
    def inner_option_convert options
      options[:per_page] = '10' if options[:per_page].blank?
      options[:sort_by] = 'date' if options[:sort_by].blank?
      options
    end

  end
end

  .alert_filter
    = select("params", "filter", Alert::Alert.all.collect{|al| al.category}.uniq.compact, {:include_blank => "ALL", :selected => "#{params[:filter]}"} )

第一段代码的问题是，内存分页
第二段代码问题是，内存取了所有alert
修改后如下：

module Service
  class UrlProfile; end
  
  class << UrlProfile
    
    def search_followers options, index
      options = inner_option_convert options
      Following::search_followers options, index
    end
    
    def search_alerts options, index
      options = inner_option_convert options
      sort_by = case options[:sort_by]
              when 'type' : 'category asc'
              else 'created_at desc'
              end
      condition= { "index_id" => index.id } 
      condition["category"] = options[:filter] unless options[:filter].blank? or options[:filter] == 'all'
      alert_list = Alert::Alert.paginate(:conditions => condition, :order=> sort_by, :page => options[:page], :per_page => options[:per_page] )   
    end
    
    private
    def inner_option_convert options
      options[:per_page] = '10' if options[:per_page].blank?
      options[:sort_by] = 'date' if options[:sort_by].blank?
      options
    end

  end
end

    = select("params", "filter", Alert::CATEGORY, {:include_blank => "ALL", :selected => "#{params[:filter]}"} )