我注意到我的editions表有多个SQL调用，尽管我在控制器中只加载了一次。更奇怪的是，尽管我正在为单个版本加载show页面，但每次调用都指向不同的edition。
控制台输出在这里：
Started GET "/editions/48" for 127.0.0.1 at 2020-03-07 08:37:53 +0530
Processing by EditionsController#show as HTML
Parameters: {"id"=>"48"}
Edition Load (0.5ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 48], ["LIMIT", 1]]
User Load (0.8ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 ORDER BY "users"."id" ASC LIMIT $2 [["id", 1], ["LIMIT", 1]]
Rendering editions/show.html.erb within layouts/application
Product Load (0.4ms) SELECT "products".* FROM "products" WHERE "products"."id" = $1 LIMIT $2 [["id", 1], ["LIMIT", 1]]
Rendered shared/_arrow.html.erb (0.3ms)
Edition Load (0.6ms) SELECT "editions".* FROM "editions" WHERE (product_id = 1 AND date < '2018-02-18') ORDER BY "editions"."date" DESC LIMIT $1 [["LIMIT", 1]]
CACHE Edition Load (0.0ms) SELECT "editions".* FROM "editions" WHERE (product_id = 1 AND date < '2018-02-18') ORDER BY "editions"."date" DESC LIMIT $1 [["LIMIT", 1]]
Edition Load (0.5ms) SELECT "editions".* FROM "editions" WHERE (product_id = 1 AND date > '2018-02-18') ORDER BY "editions"."date" ASC LIMIT $1 [["LIMIT", 1]]
CACHE Edition Load (0.0ms) SELECT "editions".* FROM "editions" WHERE (product_id = 1 AND date > '2018-02-18') ORDER BY "editions"."date" ASC LIMIT $1 [["LIMIT", 1]]
Rendered editions/_admin_controls.html.erb (0.9ms)
Section Load (0.8ms) SELECT DISTINCT "sections".* FROM "sections" INNER JOIN "contents" "contents_sections" ON "contents_sections"."section_id" = "sections"."id" INNER JOIN "contents" ON "sections"."id" = "contents"."section_id" WHERE "contents"."edition_id" = $1 AND "contents"."top_story" = $2 ORDER BY "sections"."position" ASC [["edition_id", 48], ["top_story", "f"]]
Content Load (0.6ms) SELECT "contents".* FROM "contents" WHERE "contents"."edition_id" = $1 AND "contents"."top_story" = $2 [["edition_id", 48], ["top_story", "t"]]
Content Load (0.6ms) SELECT "contents".* FROM "contents" WHERE "contents"."edition_id" = $1 AND "contents"."top_story" = $2 ORDER BY "contents"."position" ASC [["edition_id", 48], ["top_story", "t"]]
Rendered contents/_admin_controls.html.erb (0.5ms)
Source Load (0.4ms) SELECT "sources".* FROM "sources" WHERE "sources"."id" = $1 LIMIT $2 [["id", 5], ["LIMIT", 1]]
Rendered shared/_content.html.erb (7.0ms)
Rendered contents/_admin_controls.html.erb (0.3ms)
Source Load (0.4ms) SELECT "sources".* FROM "sources" WHERE "sources"."id" = $1 LIMIT $2 [["id", 2], ["LIMIT", 1]]
Rendered shared/_content.html.erb (6.9ms)
Rendered contents/_admin_controls.html.erb (0.3ms)
CACHE Source Load (0.0ms) SELECT "sources".* FROM "sources" WHERE "sources"."id" = $1 LIMIT $2 [["id", 2], ["LIMIT", 1]]
Rendered shared/_content.html.erb (7.9ms)
Rendered contents/_admin_controls.html.erb (0.3ms)
CACHE Source Load (0.0ms) SELECT "sources".* FROM "sources" WHERE "sources"."id" = $1 LIMIT $2 [["id", 2], ["LIMIT", 1]]
Rendered shared/_content.html.erb (7.0ms)
Content Load (0.6ms) SELECT "contents".* FROM "contents" WHERE "contents"."section_id" = $1 ORDER BY "contents"."position" ASC [["section_id", 2]]
Edition Load (0.4ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 40], ["LIMIT", 1]]
Edition Load (0.3ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 22], ["LIMIT", 1]]
Edition Load (0.3ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 14], ["LIMIT", 1]]
Edition Load (0.3ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 41], ["LIMIT", 1]]
CACHE Edition Load (0.0ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 14], ["LIMIT", 1]]
Edition Load (0.4ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 4], ["LIMIT", 1]]
Edition Load (0.3ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 38], ["LIMIT", 1]]
CACHE Edition Load (0.0ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 4], ["LIMIT", 1]]
Edition Load (0.4ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 34], ["LIMIT", 1]]
Edition Load (0.3ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 36], ["LIMIT", 1]]
CACHE Edition Load (0.0ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 36], ["LIMIT", 1]]
Edition Load (0.4ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 2], ["LIMIT", 1]]
CACHE Edition Load (0.0ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 2], ["LIMIT", 1]]
Edition Load (0.4ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 27], ["LIMIT", 1]]
Edition Load (0.3ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 48], ["LIMIT", 1]]
Rendered contents/_admin_controls.html.erb (0.4ms)
Source Load (0.4ms) SELECT "sources".* FROM "sources" WHERE "sources"."id" = $1 LIMIT $2 [["id", 4], ["LIMIT", 1]]
Rendered shared/_content.html.erb (7.4ms)
Edition Load (0.3ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 24], ["LIMIT", 1]]
Edition Load (0.3ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 13], ["LIMIT", 1]]
Edition Load (0.2ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 20], ["LIMIT", 1]]
Edition Load (0.4ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 37], ["LIMIT", 1]]
Edition Load (0.3ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 1], ["LIMIT", 1]]
CACHE Edition Load (0.0ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 34], ["LIMIT", 1]]
Edition Load (0.4ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 23], ["LIMIT", 1]]
CACHE Edition Load (0.0ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 24], ["LIMIT", 1]]
Edition Load (0.4ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 45], ["LIMIT", 1]]
CACHE Edition Load (0.0ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 36], ["LIMIT", 1]]
Edition Load (0.4ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 3], ["LIMIT", 1]]
Edition Load (0.3ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 15], ["LIMIT", 1]]
CACHE Edition Load (0.0ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 24], ["LIMIT", 1]]
CACHE Edition Load (0.0ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 37], ["LIMIT", 1]]
CACHE Edition Load (0.0ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 40], ["LIMIT", 1]]
Edition Load (0.4ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 47], ["LIMIT", 1]]
CACHE Edition Load (0.0ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 14], ["LIMIT", 1]]
Edition Load (0.4ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 10], ["LIMIT", 1]]
Edition Load (0.3ms) SELECT "editions".* FROM "editions" WHERE "editions"."id" = $1 LIMIT $2 [["id", 29], ["LIMIT", 1]]
Rendered editions/_edition_sections.html.erb (142.3ms)
Rendered editions/show.html.erb within layouts/application (246.2ms)
Rendered shared/_nav_searchbar.html.erb (0.8ms)
Rendered shared/_nav.html.erb (4.1ms)
Visit Load (0.5ms) SELECT "visits".* FROM "visits" WHERE "visits"."visit_token" = $1 ORDER BY "visits"."id" ASC LIMIT $2 [["visit_token", "40979cb1-0c92-486a-a274-c937560c03b1"], ["LIMIT", 1]]
(0.2ms) BEGIN
Visit Load (0.3ms) SELECT "visits".* FROM "visits" WHERE "visits"."id" = $1 LIMIT $2 [["id", 1], ["LIMIT", 1]]
SQL (0.4ms) INSERT INTO "ahoy_events" ("visit_id", "user_id", "name", "properties", "time") VALUES ($1, $2, $3, $4, $5) RETURNING "id" [["visit_id", 1], ["user_id", 1], ["name", "Load edition"], ["properties", "{"controller":"editions","action":"show","id":"48"}"], ["time", "2020-03-07 03:07:53.513209"]]
(0.9ms) COMMIT
Completed 200 OK in 400ms (Views: 367.2ms | ActiveRecord: 16.8ms)
我的其余代码可以在这里找到
我的最佳猜测是，show视图中的一些逻辑正在为数据库创建更多的查询，但我不确定在哪里或如何优化它(我有点像SQL和Rails的初学者(。事实上，这在我的生产网站上已经成为一个更大的问题，它导致Heroku发出错误，说R14 - Memory Quota Exceeded
有什么建议吗？
这被称为N+1问题。
在_editions_sections.html.erb中，您有：
if (content.edition == @edition) && (content.top_story == false)
它所做的是对循环中的每个内容加载edition以与@edition进行比较。
你可以用两种方法来解决它：
1(不是通常的解决方案(
if (content.edition_id == @edition.id) && (content.top_story == false)这将只检查
edition_id列，而不会加载edition中的所有字段。2使用
includes在
edition.rb中，使sections_with_regular_content看起来像这样：def sections_with_regular_content sections.includes(contents: :edition).where(contents: { top_story: false }) end
includes有效地计算出所需的所有id，并在单个查询中或通过联接加载它们。