development.rb设置为在dev env中使用缓存：
config.cache_classes = true
config.action_controller.perform_caching = true
config.cache_store = :dalli_store
奇怪的是在日志中，看到它：
18:57:15 web.1 | Program Load (3.1ms) SELECT "programs".* FROM "programs" WHERE "programs"."is_deleted" = 'f' AND (poster_file_name IS NOT NULL) AND ("programs"."poster_file_name" != 'yumurcatvkucuk.jpg') LIMIT 10
18:57:15 web.1 | Cache read: views/programs/21-20140408150833637850000/programs/807-20140408150843947601000/programs/925-20140408150845273240000/programs/872-20140418084359291046000/programs/132-20140408150835259856000/programs/136-20140408150835308846000/programs/140-20140408150835371772000/programs/1280-20140408150849908310000/programs/340-20140408150837584935000/programs/150-20140408150835553155000/adc205508053828cb96d93c37b9ad0f7
18:57:15 web.1 | Read fragment views/programs/21-20140408150833637850000/programs/807-20140408150843947601000/programs/925-20140408150845273240000/programs/872-20140418084359291046000/programs/132-20140408150835259856000/programs/136-20140408150835308846000/programs/140-20140408150835371772000/programs/1280-20140408150849908310000/programs/340-20140408150837584935000/programs/150-20140408150835553155000/adc205508053828cb96d93c37b9ad0f7 (0.6ms)
18:57:15 web.1 | Rendered pages/index.html.erb within layouts/application (47.8ms)
18:57:15 web.1 | Program Load (2.8ms) SELECT "programs".* FROM "programs" WHERE "programs"."is_deleted" = 'f' AND "programs"."category_id" = 10 ORDER BY "programs"."order_no" ASC LIMIT 14
18:57:15 web.1 | Category Load (2.4ms) SELECT "categories".* FROM "categories" WHERE "categories"."id" IN (10)
18:57:15 web.1 | Cache read: views/programs/8-20140408150833498130000/programs/19-20140408150833622733000/programs/30-20140408150833742922000/programs/24-20140408150833663802000/programs/1021-20140408150846580202000/programs/872-20140418084359291046000/programs/1187-20140408150848167962000/programs/866-20140408150844626941000/programs/1280-20140408150849908310000/programs/881-20140408150844749467000/programs/1376-20140408150850766221000/programs/1379-20140408150850809312000/programs/1437-20140408150851047434000/programs/3-20140408150832973507000/6c2638ad89493f0c3e448b3d66c4a1de
18:57:15 web.1 | Read fragment views/programs/8-20140408150833498130000/programs/19-20140408150833622733000/programs/30-20140408150833742922000/programs/24-20140408150833663802000/programs/1021-20140408150846580202000/programs/872-20140418084359291046000/programs/1187-20140408150848167962000/programs/866-20140408150844626941000/programs/1280-20140408150849908310000/programs/881-20140408150844749467000/programs/1376-20140408150850766221000/programs/1379-20140408150850809312000/programs/1437-20140408150851047434000/programs/3-20140408150832973507000/6c2638ad89493f0c3e448b3d66c4a1de (0.7ms)
18:57:15 web.1 | Episode Load (2.8ms) SELECT "episodes".* FROM "episodes" WHERE "episodes"."is_deleted" = 'f' AND "episodes"."episode_type_id" = 2 ORDER BY "episodes"."id" DESC LIMIT 7
18:57:15 web.1 | Program Load (2.6ms) SELECT "programs".* FROM "programs" WHERE "programs"."is_deleted" = 'f' AND "programs"."id" IN (1340, 711, 5, 1380, 1344, 1311, 1210)
18:57:15 web.1 | Cache read: views/episodes/149768-20140419064643365309000/episodes/149752-20140419064643075387000/episodes/149748-20140419064642994891000/episodes/149740-20140419064642741006000/episodes/149738-20140419064642706457000/episodes/149736-20140419064642673073000/episodes/149726-20140419064642492558000/6c2638ad89493f0c3e448b3d66c4a1de
18:57:15 web.1 | Read fragment views/episodes/149768-20140419064643365309000/episodes/149752-20140419064643075387000/episodes/149748-20140419064642994891000/episodes/149740-20140419064642741006000/episodes/149738-20140419064642706457000/episodes/149736-20140419064642673073000/episodes/149726-20140419064642492558000/6c2638ad89493f0c3e448b3d66c4a1de (0.6ms)
18:57:15 web.1 | Episode Load (3.5ms) SELECT "episodes".* FROM "episodes" WHERE "episodes"."is_deleted" = 'f' AND "episodes"."episode_type_id" = 1 ORDER BY "episodes"."id" DESC LIMIT 12
18:57:15 web.1 | Program Load (2.6ms) SELECT "programs".* FROM "programs" WHERE "programs"."is_deleted" = 'f' AND "programs"."id" IN (1016, 341)
18:57:15 web.1 | Cache read: views/episodes/149773-20140419094829793071000/episodes/149772-20140419091743738305000/episodes/149771-20140419091322119681000/episodes/149770-20140419100721271419000/episodes/149761-20140419064643243075000/episodes/149760-20140419064643225958000/episodes/149759-20140419064643207847000/episodes/149758-20140419064643182828000/episodes/149757-20140419064643166963000/episodes/149756-20140419064643149717000/episodes/149755-20140419064643132085000/episodes/149754-20140419064643113035000/6c2638ad89493f0c3e448b3d66c4a1de
18:57:15 web.1 | Read fragment views/episodes/149773-20140419094829793071000/episodes/149772-20140419091743738305000/episodes/149771-20140419091322119681000/episodes/149770-20140419100721271419000/episodes/149761-20140419064643243075000/episodes/149760-20140419064643225958000/episodes/149759-20140419064643207847000/episodes/149758-20140419064643182828000/episodes/149757-20140419064643166963000/episodes/149756-20140419064643149717000/episodes/149755-20140419064643132085000/episodes/149754-20140419064643113035000/6c2638ad89493f0c3e448b3d66c4a1de (0.6ms)
它写入和读取缓存片段但是每次刷新页面时它都运行所有SQL！我所有的刷新后日志总是一样的。它应该在第一次加载后才显示片段读数??
我尝试重新安装Dalli gem，将memcached升级到最新版本。
当我在控制台中尝试缓存和获取数据时，它是成功的。缓存也适用于生产。
我使用mini_profiler在dev env中查看SQL事务，我在mini_profiler弹出窗口中也看到了相同的SQL ...
我的观看文件中的一部分：
<% cache @latest_episodes do %>
<% @latest_episodes.each do |t| %>
<% cache(t) do %>
<%= render 'common/slider_item', episode: t, lazy_owl: true %>
<% end %>
<% end %>
<% end %>
答案 0 :(得分：0)
我仍然不太清楚这个问题，但我找到了原因。
正如我在我的问题中所述，我在视图中使用的代码是这样的：
<% cache @latest_episodes do %>
<% @latest_episodes.each do |t| %>
<% cache(t) do %>
<%= render 'common/slider_item', episode: t, lazy_owl: true %>
<% end %>
<% end %>
<% end %>
当我将实例变量更改为常规字符串键并删除了cache(t)块时，一切正常。
我猜这个问题是因为Rails必须通过处理实例变量来重新创建每个请求的缓存键。但如果重点是，Rails怎么会有自动过期机制呢？我猜这个语句表明应该总是命中数据库来创建缓存键。
任何评论都会对此表示赞赏。