ruby-on-rails - Rails - Active Record: 選択列を追加して find(:all)

Question

sum(time_entries.hours)SQL select に 新しい列を追加したいのですが、次のようなエントリを照会しています。

issues = Issue.visible.where(options[:conditions]).all(
    :include => ([:status, :project, :time_entries] + (options[:include] || [])).uniq,
    :conditions => statement,
    :order => order_option,
    :joins => query_joins(order_option.join(',')),
    :limit => options[:limit],
    :offset => options[:offset],
    :group => "#{Issue.table_name}.id"
)

この選択を生成します：

SELECT
 "issues"."id"                         AS t0_r0,
 ...
 "time_entries"."hours"                AS t3_r4,
 ...
 "versions"."sharing"                  AS t8_r9
FROM "issues"
 LEFT OUTER JOIN "projects" ON "projects"."id" = "issues"."project_id"
 LEFT OUTER JOIN "issue_statuses" ON "issue_statuses"."id" = "issues"."status_id"
 LEFT OUTER JOIN "time_entries" ON "time_entries"."issue_id" = "issues"."id"
 LEFT OUTER JOIN "users" ON "users"."id" = "issues"."assigned_to_id"
 LEFT OUTER JOIN "trackers" ON "trackers"."id" = "issues"."tracker_id"
 LEFT OUTER JOIN "enumerations"
   ON "enumerations"."id" = "issues"."priority_id" AND "enumerations"."type" IN ('IssuePriority')
 LEFT OUTER JOIN "issue_categories" ON "issue_categories"."id" = "issues"."category_id"
 LEFT OUTER JOIN "versions" ON "versions"."id" = "issues"."fixed_version_id"
WHERE "issues"."id" IN (1) AND (projects.status <> 9 AND projects.id IN (SELECT
                                                                       em.project_id
                                                                     FROM enabled_modules em
                                                                     WHERE em.name =     'issue_tracking')) AND
  ((issues.status_id IN (SELECT
                           id
                         FROM issue_statuses
                         WHERE is_closed = 'f')))
GROUP BY issues.id
ORDER BY issues.id
 DESC

:select=>"*, sum(time_entries.hours)"メソッドにハッシュパラメータを挿入してみましallたが、効果がありません。

この選択に新しい列を追加するにはどうすればよいですか? また、フィルターで使用されているため、現在の列をすべて保持する必要があります。すべての列を手で指定しない方法はありますか?

更新: Ruby 1.9.3 Rails 3.2.13