{"id":1406,"date":"2025-03-24T08:50:40","date_gmt":"2025-03-23T23:50:40","guid":{"rendered":"https:\/\/dexall.co.jp\/articles\/?p=1406"},"modified":"2025-03-24T08:50:40","modified_gmt":"2025-03-23T23:50:40","slug":"ruby-on-rails-includes%e3%83%a1%e3%82%bd%e3%83%83%e3%83%89%e5%ae%8c%e5%85%a8%e3%82%ac%e3%82%a4%e3%83%89%ef%bc%9an1%e5%95%8f%e9%a1%8c%e3%82%92%e8%a7%a3%e6%b1%ba%e3%81%99%e3%82%8b7%e3%81%a4%e3%81%ae","status":"publish","type":"post","link":"https:\/\/dexall.co.jp\/articles\/?p=1406","title":{"rendered":"Ruby on Rails includes\u30e1\u30bd\u30c3\u30c9\u5b8c\u5168\u30ac\u30a4\u30c9\uff1aN+1\u554f\u984c\u3092\u89e3\u6c7a\u3059\u308b7\u3064\u306e\u5b9f\u8df5\u30c6\u30af\u30cb\u30c3\u30af"},"content":{"rendered":"\n<div class=\"toc\"><br \/>\n<b>Warning<\/b>:  Undefined array key \"is_admin\" in <b>\/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/sango-theme\/library\/gutenberg\/dist\/classes\/Toc.php<\/b> on line <b>116<\/b><br \/>\n<br \/>\n<b>Warning<\/b>:  Undefined array key \"is_category_top\" in <b>\/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/sango-theme\/library\/gutenberg\/dist\/classes\/Toc.php<\/b> on line <b>121<\/b><br \/>\n<br \/>\n<b>Warning<\/b>:  Undefined array key \"is_top\" in <b>\/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/sango-theme\/library\/gutenberg\/dist\/classes\/Toc.php<\/b> on line <b>128<\/b><br \/>\n    <div id=\"toc_container\" class=\"sgb-toc--bullets js-smooth-scroll\" data-dialog-title=\"\u76ee\u6b21\">\n      <p class=\"toc_title\">\u76ee\u6b21 <\/p>\n      <ul class=\"toc_list\">  <li class=\"first\">    <a href=\"#i-0\">includes\u30e1\u30bd\u30c3\u30c9\u306e\u57fa\u790e\u77e5\u8b58<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-1\">includes\u30e1\u30bd\u30c3\u30c9\u304c\u89e3\u6c7a\u3059\u308b\u7279\u6709\u306e\u554f\u984c<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-2\">N+1\u554f\u984c\u3068\u306f\u4f55\u304b\uff1a\u5177\u4f53\u4f8b\u3067\u7406\u89e3\u3059\u308b<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-3\">includes\u30e1\u30bd\u30c3\u30c9\u306e\u6b63\u3057\u3044\u4f7f\u3044\u65b9<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-4\">\u57fa\u672c\u7684\u306a\u69cb\u6587\u3068\u30d1\u30e9\u30e1\u30fc\u30bf\u306e\u8aac\u660e<\/a>      <\/li>      <li>        <a href=\"#i-5\">\u30cd\u30b9\u30c8\u3055\u308c\u305f\u95a2\u9023\u4ed8\u3051\u306e\u8aad\u307f\u8fbc\u307f\u65b9<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-6\">\u8907\u6570\u306e\u95a2\u9023\u4ed8\u3051\u3092\u540c\u6642\u306b\u8aad\u307f\u8fbc\u3080\u65b9\u6cd5<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-7\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-8\">\u5fc5\u8981\u306a\u30a2\u30bd\u30b7\u30a8\u30fc\u30b7\u30e7\u30f3\u3060\u3051\u3092\u8aad\u307f\u8fbc\u3080\u91cd\u8981\u6027<\/a>      <\/li>      <li>        <a href=\"#i-9\">includes\u3068preload\u306e\u4f7f\u3044\u5206\u3051\u65b9<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-10\">eagerload\u3068\u306e\u9055\u3044\u3068\u9069\u5207\u306a\u9078\u629e\u65b9\u6cd5<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-11\">\u5b9f\u8df5\u7684\u306a\u30e6\u30fc\u30b9\u30b1\u30fc\u30b9\u89e3\u8aac<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-12\">\u30d6\u30ed\u30b0\u30b7\u30b9\u30c6\u30e0\u3067\u306e\u6295\u7a3f\u3068\u8457\u8005\u306e\u52b9\u7387\u7684\u306a\u8aad\u307f\u8fbc\u307f<\/a>      <\/li>      <li>        <a href=\"#i-13\">EC\u30b5\u30a4\u30c8\u3067\u306e\u5546\u54c1\u3068\u5728\u5eab\u60c5\u5831\u306e\u6700\u9069\u5316<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-14\">SNS\u30a2\u30d7\u30ea\u3067\u306e\u30e6\u30fc\u30b6\u30fc\u3068\u6295\u7a3f\u306e\u95a2\u9023\u4ed8\u3051<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-15\">includes\u30e1\u30bd\u30c3\u30c9\u306e\u30c7\u30d0\u30c3\u30b0\u3068\u30c8\u30e9\u30d6\u30eb\u30b7\u30e5\u30fc\u30c6\u30a3\u30f3\u30b0<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-16\">\u3088\u304f\u3042\u308b\u5b9f\u88c5\u30df\u30b9\u3068\u305d\u306e\u89e3\u6c7a\u65b9\u6cd5<\/a>      <\/li>      <li>        <a href=\"#i-17\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u30e2\u30cb\u30bf\u30ea\u30f3\u30b0\u306e\u65b9\u6cd5<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-18\">SQL\u30af\u30a8\u30ea\u306e\u6700\u9069\u5316\u30c6\u30af\u30cb\u30c3\u30af<\/a>      <\/li>    <\/ul>  <\/li>  <li class=\"last\">    <a href=\"#i-19\">\u767a\u5c55\u7684\u306a\u4f7f\u7528\u65b9\u6cd5\u3068\u30c6\u30af\u30cb\u30c3\u30af<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-20\">\u6761\u4ef6\u4ed8\u304d\u3067\u306e\u95a2\u9023\u30c7\u30fc\u30bf\u306e\u8aad\u307f\u8fbc\u307f<\/a>      <\/li>      <li>        <a href=\"#i-21\">\u30ab\u30b9\u30bf\u30e0SQL\u3092\u4f7f\u7528\u3057\u305f\u6700\u9069\u5316<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-22\">\u5927\u898f\u6a21\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3067\u306e\u5b9f\u88c5\u30d1\u30bf\u30fc\u30f3<\/a>      <\/li>    <\/ul>  <\/li><\/ul>\n      <a href=\"#\" class=\"sgb-toc-button js-toc-button\" rel=\"nofollow\" data-open-dialog=\"true\"><i class=\"fa fa-list\"><\/i><span class=\"sgb-toc-button__text\">\u76ee\u6b21\u3078<\/span><\/a>\n    <\/div><\/div><h2 class=\"wp-block-heading\" id=\"i-0\">includes\u30e1\u30bd\u30c3\u30c9\u306e\u57fa\u790e\u77e5\u8b58<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-1\">includes\u30e1\u30bd\u30c3\u30c9\u304c\u89e3\u6c7a\u3059\u308b\u7279\u6709\u306e\u554f\u984c<\/h3>\n\n\n\n<p>ActiveRecord\u306eincludes\u30e1\u30bd\u30c3\u30c9\u306f\u3001Rails\u958b\u767a\u306b\u304a\u3051\u308b\u6700\u3082\u91cd\u8981\u306a\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u30c4\u30fc\u30eb\u306e1\u3064\u3067\u3059\u3002\u3053\u306e\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u95a2\u9023\u3059\u308b\u30c6\u30fc\u30d6\u30eb\u306e\u30c7\u30fc\u30bf\u3092\u52b9\u7387\u7684\u306b\u4e00\u62ec\u8aad\u307f\u8fbc\u307f\u3059\u308b\u3053\u3068\u3067\u3001\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u3078\u306e\u30a2\u30af\u30bb\u30b9\u56de\u6570\u3092\u524a\u6e1b\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<p>\u4e3b\u306a\u89e3\u6c7a\u8ab2\u984c\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u30af\u30a8\u30ea\u306e\u524a\u6e1b<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u95a2\u9023\u30c7\u30fc\u30bf\u306e\u500b\u5225\u8aad\u307f\u8fbc\u307f\u3092\u9632\u6b62<\/li>\n\n\n\n<li>\u30b5\u30fc\u30d0\u30fc\u3068\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u9593\u306e\u901a\u4fe1\u3092\u6700\u5c0f\u5316<\/li>\n\n\n\n<li>\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306e\u30ec\u30b9\u30dd\u30f3\u30b9\u30bf\u30a4\u30e0\u3092\u6539\u5584<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30e1\u30e2\u30ea\u4f7f\u7528\u306e\u6700\u9069\u5316<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5fc5\u8981\u306a\u30c7\u30fc\u30bf\u30921\u56de\u306e\u30af\u30a8\u30ea\u3067\u53d6\u5f97<\/li>\n\n\n\n<li>\u95a2\u9023\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30ad\u30e3\u30c3\u30b7\u30e5\u3092\u52b9\u7387\u7684\u306b\u7ba1\u7406<\/li>\n\n\n\n<li>\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306e\u30e1\u30e2\u30ea\u6d88\u8cbb\u3092\u6291\u5236<\/li>\n<\/ul>\n\n\n\n<p>\u4f8b\u3048\u3070\u3001\u30d6\u30ed\u30b0\u30b7\u30b9\u30c6\u30e0\u3067\u8a18\u4e8b\u3068\u8457\u8005\u306e\u60c5\u5831\u3092\u53d6\u5f97\u3059\u308b\u5834\u5408\u3092\u8003\u3048\u3066\u307f\u307e\u3057\u3087\u3046\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># includes\u3092\u4f7f\u7528\u3057\u306a\u3044\u5834\u5408\uff08\u975e\u52b9\u7387\uff09\nposts = Post.all\nposts.each do |post|\n  puts \"#{post.title} by #{post.author.name}\"  # \u5404\u6295\u7a3f\u3054\u3068\u306b\u8457\u8005\u60c5\u5831\u3092\u53d6\u5f97\nend\n\n# includes\u3092\u4f7f\u7528\u3059\u308b\u5834\u5408\uff08\u52b9\u7387\u7684\uff09\nposts = Post.includes(:author).all\nposts.each do |post|\n  puts \"#{post.title} by #{post.author.name}\"  # \u8457\u8005\u60c5\u5831\u306f\u65e2\u306b\u8aad\u307f\u8fbc\u307f\u6e08\u307f\nend<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-2\">N+1\u554f\u984c\u3068\u306f\u4f55\u304b\uff1a\u5177\u4f53\u4f8b\u3067\u7406\u89e3\u3059\u308b<\/h3>\n\n\n\n<p>N+1\u554f\u984c\u306f\u3001Rails\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306b\u304a\u3051\u308b\u6700\u3082\u4e00\u822c\u7684\u306a\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u554f\u984c\u306e1\u3064\u3067\u3059\u3002\u3053\u306e\u554f\u984c\u306f\u3001\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u306b\u5bfe\u3057\u3066\u95a2\u9023\u30c7\u30fc\u30bf\u3092\u500b\u5225\u306b\u53d6\u5f97\u3059\u308b\u969b\u306b\u767a\u751f\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<p>\u5177\u4f53\u4f8b\u3067\u898b\u3066\u307f\u307e\u3057\u3087\u3046\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u69cb\u9020\nclass Order &lt; ApplicationRecord\n  belongs_to :customer\n  has_many :items\nend\n\n# N+1\u554f\u984c\u304c\u767a\u751f\u3059\u308b\u30b3\u30fc\u30c9\norders = Order.all  # 1\u56de\u76ee\u306e\u30af\u30a8\u30ea\uff1a\u5168\u3066\u306e\u6ce8\u6587\u3092\u53d6\u5f97\norders.each do |order|\n  puts order.customer.name  # N\u56de\u306e\u30af\u30a8\u30ea\uff1a\u5404\u6ce8\u6587\u3054\u3068\u306b\u9867\u5ba2\u60c5\u5831\u3092\u53d6\u5f97\nend<\/pre>\n\n\n\n<p>\u3053\u306e\u30b3\u30fc\u30c9\u306e\u5b9f\u884c\u6642\u306b\u767a\u751f\u3059\u308bSQL\u30af\u30a8\u30ea\u3092\u898b\u3066\u307f\u307e\u3057\u3087\u3046\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">SELECT * FROM orders;  -- 1\u56de\u76ee\u306e\u30af\u30a8\u30ea\nSELECT * FROM customers WHERE id = 1;  -- 2\u56de\u76ee\u4ee5\u964d\u306e\u30af\u30a8\u30ea\uff08\u6ce8\u6587\u306e\u6570\u3060\u3051\u5b9f\u884c\uff09\nSELECT * FROM customers WHERE id = 2;\nSELECT * FROM customers WHERE id = 3;\n...<\/pre>\n\n\n\n<p>includes\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3057\u3066\u6700\u9069\u5316\u3059\u308b\u3068\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u6700\u9069\u5316\u3055\u308c\u305f\u30b3\u30fc\u30c9\norders = Order.includes(:customer)\norders.each do |order|\n  puts order.customer.name  # \u8ffd\u52a0\u306e\u30af\u30a8\u30ea\u306f\u767a\u751f\u3057\u306a\u3044\nend\n\n# \u751f\u6210\u3055\u308c\u308bSQL\nSELECT * FROM orders;\nSELECT * FROM customers WHERE id IN (1, 2, 3, ...);  -- 1\u56de\u306e\u30af\u30a8\u30ea\u3067\u5168\u3066\u306e\u9867\u5ba2\u60c5\u5831\u3092\u53d6\u5f97<\/pre>\n\n\n\n<p>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u6bd4\u8f03\uff1a<\/p>\n\n\n<div id=\"id-1741c4ca-bb99-4c17-8c57-c73349c69a44\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u30a2\u30d7\u30ed\u30fc\u30c1<\/th><th>\u30af\u30a8\u30ea\u6570<\/th><th>\u30ec\u30b9\u30dd\u30f3\u30b9\u30bf\u30a4\u30e0<\/th><th>\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf<\/th><\/tr><\/thead><tbody><tr><td>includes\u672a\u4f7f\u7528<\/td><td>N + 1<\/td><td>\u9045\u3044\uff08\u7dda\u5f62\u5897\u52a0\uff09<\/td><td>\u5c11\u306a\u3044<\/td><\/tr><tr><td>includes\u4f7f\u7528<\/td><td>2<\/td><td>\u901f\u3044\uff08\u307b\u307c\u4e00\u5b9a\uff09<\/td><td>\u3084\u3084\u591a\u3044<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<p>\u6ce8\u610f\u70b9\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>includes\u306f\u5fc5\u8981\u306a\u95a2\u9023\u30c7\u30fc\u30bf\u306e\u307f\u3092\u6307\u5b9a\u3059\u308b<\/li>\n\n\n\n<li>\u5927\u91cf\u306e\u30ec\u30b3\u30fc\u30c9\u3092\u6271\u3046\u5834\u5408\u306f\u30da\u30fc\u30b8\u30cd\u30fc\u30b7\u30e7\u30f3\u3068\u7d44\u307f\u5408\u308f\u305b\u308b<\/li>\n\n\n\n<li>\u8907\u96d1\u306a\u95a2\u9023\u3092\u6271\u3046\u5834\u5408\u306f\u3001\u5fc5\u8981\u306b\u5fdc\u3058\u3066preload\u3084eager_load\u3092\u691c\u8a0e\u3059\u308b<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-3\">includes\u30e1\u30bd\u30c3\u30c9\u306e\u6b63\u3057\u3044\u4f7f\u3044\u65b9<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-4\">\u57fa\u672c\u7684\u306a\u69cb\u6587\u3068\u30d1\u30e9\u30e1\u30fc\u30bf\u306e\u8aac\u660e<\/h3>\n\n\n\n<p>includes\u30e1\u30bd\u30c3\u30c9\u306f\u3001ActiveRecord\u306e\u30af\u30a8\u30ea\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30fc\u30b9\u306e\u4e00\u90e8\u3068\u3057\u3066\u3001\u69d8\u3005\u306a\u65b9\u6cd5\u3067\u5229\u7528\u3067\u304d\u307e\u3059\u3002\u57fa\u672c\u7684\u306a\u69cb\u6587\u304b\u3089\u5fdc\u7528\u7684\u306a\u4f7f\u3044\u65b9\u307e\u3067\u3001\u6bb5\u968e\u7684\u306b\u89e3\u8aac\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<p>\u57fa\u672c\u69cb\u6587\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u5358\u4e00\u306e\u95a2\u9023\u4ed8\u3051\u3092\u8aad\u307f\u8fbc\u3080\nUser.includes(:posts)\n\n# \u8907\u6570\u306e\u95a2\u9023\u4ed8\u3051\u3092\u8aad\u307f\u8fbc\u3080\nUser.includes(:posts, :comments)\n\n# \u6761\u4ef6\u3068\u7d44\u307f\u5408\u308f\u305b\u308b\nUser.includes(:posts).where(active: true)\n\n# \u30b9\u30b3\u30fc\u30d7\u3068\u7d44\u307f\u5408\u308f\u305b\u308b\nUser.active.includes(:posts)<\/pre>\n\n\n\n<p>\u30d1\u30e9\u30e1\u30fc\u30bf\u306e\u7a2e\u985e\u3068\u4f7f\u7528\u4f8b\uff1a<\/p>\n\n\n<div id=\"id-3bc368aa-c516-4e73-a11b-5ddce5af436f\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u30d1\u30e9\u30e1\u30fc\u30bf\u5f62\u5f0f<\/th><th>\u4f7f\u7528\u4f8b<\/th><th>\u8aac\u660e<\/th><\/tr><\/thead><tbody><tr><td>\u30b7\u30f3\u30dc\u30eb<\/td><td><code>includes(:posts)<\/code><\/td><td>\u5358\u4e00\u306e\u95a2\u9023\u4ed8\u3051\u3092\u6307\u5b9a<\/td><\/tr><tr><td>\u914d\u5217<\/td><td><code>includes([:posts, :comments])<\/code><\/td><td>\u8907\u6570\u306e\u95a2\u9023\u4ed8\u3051\u3092\u6307\u5b9a<\/td><\/tr><tr><td>\u30cf\u30c3\u30b7\u30e5<\/td><td><code>includes(posts: :comments)<\/code><\/td><td>\u30cd\u30b9\u30c8\u3055\u308c\u305f\u95a2\u9023\u4ed8\u3051\u3092\u6307\u5b9a<\/td><\/tr><tr><td>\u6df7\u5408<\/td><td><code>includes(:profile, posts: :comments)<\/code><\/td><td>\u8907\u5408\u7684\u306a\u95a2\u9023\u4ed8\u3051\u3092\u6307\u5b9a<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<h3 class=\"wp-block-heading\" id=\"i-5\">\u30cd\u30b9\u30c8\u3055\u308c\u305f\u95a2\u9023\u4ed8\u3051\u306e\u8aad\u307f\u8fbc\u307f\u65b9<\/h3>\n\n\n\n<p>\u8907\u96d1\u306a\u95a2\u9023\u4ed8\u3051\u3092\u6301\u3064\u30e2\u30c7\u30eb\u3067\u306f\u3001\u30cd\u30b9\u30c8\u3055\u308c\u305f\u95a2\u9023\u4ed8\u3051\u306e\u9069\u5207\u306a\u8aad\u307f\u8fbc\u307f\u304c\u91cd\u8981\u3067\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u30e2\u30c7\u30eb\u5b9a\u7fa9\nclass User &lt; ApplicationRecord\n  has_many :posts\n  has_one :profile\nend\n\nclass Post &lt; ApplicationRecord\n  belongs_to :user\n  has_many :comments\n  has_many :tags\nend\n\n# \u30cd\u30b9\u30c8\u3055\u308c\u305f\u95a2\u9023\u4ed8\u3051\u306e\u8aad\u307f\u8fbc\u307f\u4f8b\nusers = User.includes(posts: [:comments, :tags])\n\n# \u3088\u308a\u8907\u96d1\u306a\u30cd\u30b9\u30c8\nusers = User.includes(\n  profile: :avatar,\n  posts: {\n    comments: :author,\n    tags: :category\n  }\n)<\/pre>\n\n\n\n<p>\u51e6\u7406\u306e\u6d41\u308c\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>User\u30c6\u30fc\u30d6\u30eb\u304b\u3089\u30c7\u30fc\u30bf\u3092\u53d6\u5f97<\/li>\n\n\n\n<li>\u95a2\u9023\u3059\u308b Profile \u30c7\u30fc\u30bf\u3092\u53d6\u5f97<\/li>\n\n\n\n<li>\u95a2\u9023\u3059\u308b Posts \u30c7\u30fc\u30bf\u3092\u53d6\u5f97<\/li>\n\n\n\n<li>Posts \u306b\u7d10\u3065\u304f Comments \u3068 Tags \u3092\u53d6\u5f97<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-6\">\u8907\u6570\u306e\u95a2\u9023\u4ed8\u3051\u3092\u540c\u6642\u306b\u8aad\u307f\u8fbc\u3080\u65b9\u6cd5<\/h3>\n\n\n\n<p>\u5927\u898f\u6a21\u306a\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3067\u306f\u3001\u8907\u6570\u306e\u95a2\u9023\u4ed8\u3051\u3092\u52b9\u7387\u7684\u306b\u8aad\u307f\u8fbc\u3080\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u8907\u6570\u306e\u95a2\u9023\u4ed8\u3051\u3092\u5e73\u884c\u3057\u3066\u8aad\u307f\u8fbc\u3080\nclass BlogPost &lt; ApplicationRecord\n  has_many :comments\n  has_many :likes\n  belongs_to :author\n  has_many :categories\nend\n\n# \u57fa\u672c\u7684\u306a\u8907\u6570\u8aad\u307f\u8fbc\u307f\nposts = BlogPost.includes(:comments, :likes, :author)\n\n# \u3088\u308a\u8907\u96d1\u306a\u8907\u6570\u8aad\u307f\u8fbc\u307f\nposts = BlogPost.includes(\n  :author,\n  comments: :user,\n  likes: :user,\n  categories: :parent_category\n)\n\n# \u6761\u4ef6\u4ed8\u304d\u306e\u8907\u6570\u8aad\u307f\u8fbc\u307f\nposts = BlogPost.includes(:comments, :likes)\n                .where(published: true)\n                .order(created_at: :desc)<\/pre>\n\n\n\n<p>\u52b9\u7387\u7684\u306a\u8aad\u307f\u8fbc\u307f\u306e\u305f\u3081\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u5fc5\u8981\u306a\u95a2\u9023\u4ed8\u3051\u306e\u898b\u6975\u3081<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5b9f\u969b\u306b\u4f7f\u7528\u3059\u308b\u95a2\u9023\u30c7\u30fc\u30bf\u306e\u307f\u3092\u6307\u5b9a<\/li>\n\n\n\n<li>\u4e0d\u8981\u306a\u30c7\u30fc\u30bf\u306e\u8aad\u307f\u8fbc\u307f\u3092\u907f\u3051\u308b<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30af\u30a8\u30ea\u306e\u6700\u9069\u5316<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>where\u3084order\u306a\u3069\u306e\u6761\u4ef6\u306f\u3001includes\u306e\u524d\u306b\u914d\u7f6e<\/li>\n\n\n\n<li>\u8907\u96d1\u306a\u6761\u4ef6\u306f\u30b9\u30b3\u30fc\u30d7\u3068\u3057\u3066\u5b9a\u7fa9<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30e1\u30e2\u30ea\u4f7f\u7528\u306e\u8003\u616e<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5927\u91cf\u306e\u30ec\u30b3\u30fc\u30c9\u3092\u6271\u3046\u5834\u5408\u306f\u30da\u30fc\u30b8\u30cd\u30fc\u30b7\u30e7\u30f3\u3092\u4f7f\u7528<\/li>\n\n\n\n<li>\u5fc5\u8981\u306b\u5fdc\u3058\u3066find_each\u3084batch\u51e6\u7406\u3092\u691c\u8a0e<\/li>\n<\/ul>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u30da\u30fc\u30b8\u30cd\u30fc\u30b7\u30e7\u30f3\u3068\u306e\u7d44\u307f\u5408\u308f\u305b\u4f8b\nposts = BlogPost.includes(:comments, :author)\n                .page(params[:page])\n                .per(20)\n\n# \u30d0\u30c3\u30c1\u51e6\u7406\u3068\u306e\u7d44\u307f\u5408\u308f\u305b\u4f8b\nBlogPost.includes(:comments).find_each do |post|\n  # \u5404\u6295\u7a3f\u306b\u5bfe\u3059\u308b\u51e6\u7406\nend<\/pre>\n\n\n\n<p>\u5b9f\u88c5\u6642\u306e\u6ce8\u610f\u70b9\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>N+1\u554f\u984c\u304c\u89e3\u6d88\u3055\u308c\u3066\u3044\u308b\u304b\u78ba\u8a8d\u3059\u308b<\/li>\n\n\n\n<li>\u751f\u6210\u3055\u308c\u308bSQL\u3092\u30ed\u30b0\u3067\u78ba\u8a8d\u3059\u308b<\/li>\n\n\n\n<li>\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3092\u30e2\u30cb\u30bf\u30ea\u30f3\u30b0\u3059\u308b<\/li>\n\n\n\n<li>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3078\u306e\u5f71\u97ff\u3092\u6e2c\u5b9a\u3059\u308b<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-7\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-8\">\u5fc5\u8981\u306a\u30a2\u30bd\u30b7\u30a8\u30fc\u30b7\u30e7\u30f3\u3060\u3051\u3092\u8aad\u307f\u8fbc\u3080\u91cd\u8981\u6027<\/h3>\n\n\n\n<p>ActiveRecord\u306eincludes\u30e1\u30bd\u30c3\u30c9\u3092\u52b9\u679c\u7684\u306b\u4f7f\u7528\u3059\u308b\u306b\u306f\u3001\u5fc5\u8981\u306a\u30a2\u30bd\u30b7\u30a8\u30fc\u30b7\u30e7\u30f3\u306e\u9069\u5207\u306a\u9078\u629e\u304c\u4e0d\u53ef\u6b20\u3067\u3059\u3002\u904e\u5270\u306a\u8aad\u307f\u8fbc\u307f\u306f\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u4f4e\u4e0b\u3092\u62db\u304f\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<p>\u6700\u9069\u5316\u306e\u30dd\u30a4\u30f3\u30c8\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30c7\u30fc\u30bf\u306e\u4f7f\u7528\u7bc4\u56f2\u306e\u7279\u5b9a<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u60aa\u3044\u4f8b\uff1a\u4e0d\u8981\u306a\u30c7\u30fc\u30bf\u307e\u3067\u8aad\u307f\u8fbc\u3080\n@posts = Post.includes(:comments, :tags, :categories, :author)\n\n# \u826f\u3044\u4f8b\uff1a\u5fc5\u8981\u306a\u30c7\u30fc\u30bf\u306e\u307f\u3092\u8aad\u307f\u8fbc\u3080\n@posts = Post.includes(:author).where(published: true)<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li>\u9078\u629e\u7684\u306a\u30ab\u30e9\u30e0\u8aad\u307f\u8fbc\u307f<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u5fc5\u8981\u306a\u30ab\u30e9\u30e0\u306e\u307f\u3092\u6307\u5b9a\n@posts = Post.includes(:author)\n            .select('posts.title, posts.published_at')\n            .where(published: true)\n\n# \u95a2\u9023\u30e2\u30c7\u30eb\u306e\u7279\u5b9a\u306e\u30ab\u30e9\u30e0\u306e\u307f\u3092\u8aad\u307f\u8fbc\u3080\n@posts = Post.includes(:author)\n            .select('posts.*, authors.name as author_name')\n            .references(:authors)<\/pre>\n\n\n\n<p>\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u306e\u6bd4\u8f03\uff1a<\/p>\n\n\n<div id=\"id-dbed25a7-4531-408e-a691-a54f5e52f427\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u8aad\u307f\u8fbc\u307f\u65b9\u6cd5<\/th><th>\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf<\/th><th>\u30ec\u30b9\u30dd\u30f3\u30b9\u6642\u9593<\/th><th>\u63a8\u5968\u3055\u308c\u308b\u4f7f\u7528\u5834\u9762<\/th><\/tr><\/thead><tbody><tr><td>\u5168\u30c7\u30fc\u30bf\u8aad\u307f\u8fbc\u307f<\/td><td>\u5927<\/td><td>\u9045\u3044<\/td><td>\u5168\u3066\u306e\u30c7\u30fc\u30bf\u304c\u5fc5\u8981\u306a\u5834\u5408<\/td><\/tr><tr><td>\u9078\u629e\u7684\u8aad\u307f\u8fbc\u307f<\/td><td>\u5c0f<\/td><td>\u901f\u3044<\/td><td>\u7279\u5b9a\u306e\u30c7\u30fc\u30bf\u306e\u307f\u5fc5\u8981\u306a\u5834\u5408<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<h3 class=\"wp-block-heading\" id=\"i-9\">includes\u3068preload\u306e\u4f7f\u3044\u5206\u3051\u65b9<\/h3>\n\n\n\n<p>includes\u3068preload\u306f\u4f3c\u305f\u3088\u3046\u306a\u6a5f\u80fd\u3092\u6301\u3061\u307e\u3059\u304c\u3001\u4f7f\u7528\u3059\u308b\u3079\u304d\u72b6\u6cc1\u304c\u7570\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<p>preload\u306e\u7279\u5fb4\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># preload\u306e\u57fa\u672c\u7684\u306a\u4f7f\u7528\u6cd5\nusers = User.preload(:posts)\n# \u751f\u6210\u3055\u308c\u308bSQL:\n# SELECT * FROM users\n# SELECT * FROM posts WHERE user_id IN (1, 2, 3...)\n\n# preload\u306f\u95a2\u9023\u30c6\u30fc\u30d6\u30eb\u306e\u6761\u4ef6\u6307\u5b9a\u304c\u4e0d\u53ef\u80fd\n# \u3053\u308c\u306f\u30a8\u30e9\u30fc\u306b\u306a\u308b\nusers = User.preload(:posts).where('posts.created_at &gt; ?', 1.week.ago)<\/pre>\n\n\n\n<p>includes\u306e\u7279\u5fb4\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># includes\u306e\u57fa\u672c\u7684\u306a\u4f7f\u7528\u6cd5\nusers = User.includes(:posts)\n\n# \u95a2\u9023\u30c6\u30fc\u30d6\u30eb\u306e\u6761\u4ef6\u6307\u5b9a\u304c\u53ef\u80fd\nusers = User.includes(:posts)\n            .where('posts.created_at &gt; ?', 1.week.ago)\n            .references(:posts)<\/pre>\n\n\n\n<p>\u4f7f\u3044\u5206\u3051\u306e\u57fa\u6e96\uff1a<\/p>\n\n\n<div id=\"id-63c3d86d-2163-45f0-9aaa-e13cbbd819e3\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u6a5f\u80fd<\/th><th>preload<\/th><th>includes<\/th><\/tr><\/thead><tbody><tr><td>\u5225\u30af\u30a8\u30ea\u3067\u306e\u8aad\u307f\u8fbc\u307f<\/td><td>\u25cb<\/td><td>\u00d7<\/td><\/tr><tr><td>JOIN\u53e5\u306e\u4f7f\u7528<\/td><td>\u00d7<\/td><td>\u25cb<\/td><\/tr><tr><td>WHERE\u53e5\u3067\u306e\u95a2\u9023\u4ed8\u3051<\/td><td>\u00d7<\/td><td>\u25cb<\/td><\/tr><tr><td>\u30e1\u30e2\u30ea\u52b9\u7387<\/td><td>\u9ad8\u3044<\/td><td>\u5834\u5408\u306b\u3088\u308b<\/td><\/tr><tr><td>\u30af\u30a8\u30ea\u306e\u67d4\u8edf\u6027<\/td><td>\u4f4e\u3044<\/td><td>\u9ad8\u3044<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<h3 class=\"wp-block-heading\" id=\"i-10\">eagerload\u3068\u306e\u9055\u3044\u3068\u9069\u5207\u306a\u9078\u629e\u65b9\u6cd5<\/h3>\n\n\n\n<p>eager_load\u306f\u5e38\u306bLEFT OUTER JOIN\u3092\u4f7f\u7528\u3059\u308b\u70b9\u3067includes\u3084preload\u3068\u7570\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># eager_load\u306e\u57fa\u672c\u7684\u306a\u4f7f\u7528\u6cd5\nusers = User.eager_load(:posts)\n# \u751f\u6210\u3055\u308c\u308bSQL:\n# SELECT users.*, posts.* FROM users\n# LEFT OUTER JOIN posts ON posts.user_id = users.id\n\n# \u8907\u6570\u306e\u95a2\u9023\u4ed8\u3051\u3092\u4f7f\u7528\u3059\u308b\u5834\u5408\nusers = User.eager_load(:posts, :comments)<\/pre>\n\n\n\n<p>\u4e09\u8005\u306e\u6bd4\u8f03\u3068\u9078\u629e\u57fa\u6e96\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30af\u30a8\u30ea\u751f\u6210\u65b9\u6cd5<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># preload: \u5e38\u306b\u5225\u30af\u30a8\u30ea\nUser.preload(:posts)\n# SELECT * FROM users\n# SELECT * FROM posts WHERE user_id IN (1, 2, 3...)\n\n# includes: \u72b6\u6cc1\u306b\u5fdc\u3058\u3066\u6700\u9069\u5316\nUser.includes(:posts)\n# \uff08\u6761\u4ef6\u306a\u3057\uff09\u540c\u4e0a\n# \uff08\u6761\u4ef6\u3042\u308a\uff09LEFT OUTER JOIN\n\n# eager_load: \u5e38\u306bJOIN\nUser.eager_load(:posts)\n# LEFT OUTER JOIN posts ON posts.user_id = users.id<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u7279\u6027\uff1a<br>\u30e1\u30bd\u30c3\u30c9 \u30af\u30a8\u30ea\u6570 \u30e1\u30e2\u30ea\u4f7f\u7528\u91cf JOIN\u4f7f\u7528 \u9069\u3057\u3066\u3044\u308b\u5834\u9762<br>preload \u8907\u6570 \u4e2d \u306a\u3057 \u95a2\u9023\u30c7\u30fc\u30bf\u306b\u6761\u4ef6\u304c\u306a\u3044\u5834\u5408<br>includes \u72b6\u6cc1\u306b\u3088\u308b \u72b6\u6cc1\u306b\u3088\u308b \u72b6\u6cc1\u306b\u3088\u308b \u6c4e\u7528\u7684\u306a\u4f7f\u7528<br>eager_load 1 \u5927 \u3042\u308a \u8907\u96d1\u306a\u6761\u4ef6\u304c\u5fc5\u8981\u306a\u5834\u5408 \u9078\u629e\u306e\u305f\u3081\u306e\u30c1\u30a7\u30c3\u30af\u30ea\u30b9\u30c8\uff1a<ul><li>\u95a2\u9023\u30c6\u30fc\u30d6\u30eb\u306b\u6761\u4ef6\u3092\u4ed8\u3051\u308b\u5fc5\u8981\u304c\u3042\u308b\u304b<\/li><li>\u30c7\u30fc\u30bf\u91cf\u306f\u3069\u306e\u7a0b\u5ea6\u304b<\/li><li>\u30e1\u30e2\u30ea\u5236\u7d04\u306f\u3042\u308b\u304b<\/li><li>\u30af\u30a8\u30ea\u306e\u5b9f\u884c\u56de\u6570\u3092\u6700\u5c0f\u9650\u306b\u6291\u3048\u308b\u5fc5\u8981\u304c\u3042\u308b\u304b<\/li><\/ul>\u3053\u308c\u3089\u306e\u8981\u7d20\u3092\u8003\u616e\u3057\u3001\u9069\u5207\u306a\u30e1\u30bd\u30c3\u30c9\u3092\u9078\u629e\u3059\u308b\u3053\u3068\u3067\u3001\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u6700\u9069\u5316\u3067\u304d\u307e\u3059\u3002<\/li>\n<\/ol>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-11\">\u5b9f\u8df5\u7684\u306a\u30e6\u30fc\u30b9\u30b1\u30fc\u30b9\u89e3\u8aac<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-12\">\u30d6\u30ed\u30b0\u30b7\u30b9\u30c6\u30e0\u3067\u306e\u6295\u7a3f\u3068\u8457\u8005\u306e\u52b9\u7387\u7684\u306a\u8aad\u307f\u8fbc\u307f<\/h3>\n\n\n\n<p>\u30d6\u30ed\u30b0\u30b7\u30b9\u30c6\u30e0\u3067\u306f\u3001\u6295\u7a3f\u3001\u8457\u8005\u3001\u30ab\u30c6\u30b4\u30ea\u3001\u30b3\u30e1\u30f3\u30c8\u306a\u3069\u3001\u8907\u6570\u306e\u30e2\u30c7\u30eb\u9593\u306e\u95a2\u9023\u3092\u52b9\u7387\u7684\u306b\u6271\u3046\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<p>\u30e2\u30c7\u30eb\u69cb\u6210\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class Post &lt; ApplicationRecord\n  belongs_to :author\n  has_many :comments\n  has_many :post_categories\n  has_many :categories, through: :post_categories\n  has_many :likes\nend\n\nclass Author &lt; ApplicationRecord\n  has_many :posts\n  has_one :profile\nend\n\nclass Comment &lt; ApplicationRecord\n  belongs_to :post\n  belongs_to :user\nend<\/pre>\n\n\n\n<p>\u52b9\u7387\u7684\u306a\u5b9f\u88c5\u4f8b\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u30c8\u30c3\u30d7\u30da\u30fc\u30b8\u306e\u6700\u65b0\u8a18\u4e8b\u4e00\u89a7\ndef index\n  @posts = Post.includes(:author, :categories)\n              .with_attached_thumbnail\n              .recent\n              .limit(10)\nend\n\n# \u8a18\u4e8b\u8a73\u7d30\u30da\u30fc\u30b8\ndef show\n  @post = Post.includes(\n    :author,\n    :categories,\n    comments: [:user, :replies]\n  ).find(params[:id])\nend\n\n# \u8457\u8005\u306e\u30c0\u30c3\u30b7\u30e5\u30dc\u30fc\u30c9\ndef dashboard\n  @author = Author.includes(\n    :profile,\n    posts: [:categories, :likes]\n  ).find(current_author.id)\nend<\/pre>\n\n\n\n<p>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6539\u5584\u52b9\u679c\uff1a<\/p>\n\n\n<div id=\"id-90d6e0d4-10a4-4045-986d-013e9ac659b2\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u30b7\u30ca\u30ea\u30aa<\/th><th>\u30af\u30a8\u30ea\u524a\u6e1b\u6570<\/th><th>\u30ec\u30b9\u30dd\u30f3\u30b9\u6642\u9593\u6539\u5584<\/th><\/tr><\/thead><tbody><tr><td>\u30c8\u30c3\u30d7\u30da\u30fc\u30b8<\/td><td>20+ \u2192 3<\/td><td>\u7d0470%\u524a\u6e1b<\/td><\/tr><tr><td>\u8a18\u4e8b\u8a73\u7d30<\/td><td>30+ \u2192 4<\/td><td>\u7d0480%\u524a\u6e1b<\/td><\/tr><tr><td>\u30c0\u30c3\u30b7\u30e5\u30dc\u30fc\u30c9<\/td><td>40+ \u2192 5<\/td><td>\u7d0485%\u524a\u6e1b<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<h3 class=\"wp-block-heading\" id=\"i-13\">EC\u30b5\u30a4\u30c8\u3067\u306e\u5546\u54c1\u3068\u5728\u5eab\u60c5\u5831\u306e\u6700\u9069\u5316<\/h3>\n\n\n\n<p>EC\u30b5\u30a4\u30c8\u3067\u306f\u3001\u5546\u54c1\u3001\u5728\u5eab\u3001\u4fa1\u683c\u3001\u30ab\u30c6\u30b4\u30ea\u306a\u3069\u306e\u60c5\u5831\u3092\u52b9\u7387\u7684\u306b\u8868\u793a\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<p>\u30e2\u30c7\u30eb\u69cb\u6210\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class Product &lt; ApplicationRecord\n  belongs_to :category\n  has_many :variants\n  has_many :stock_items, through: :variants\n  has_many :prices\n  has_many :reviews\nend\n\nclass Variant &lt; ApplicationRecord\n  belongs_to :product\n  has_many :stock_items\n  has_many :prices\nend\n\nclass StockItem &lt; ApplicationRecord\n  belongs_to :variant\n  belongs_to :warehouse\nend<\/pre>\n\n\n\n<p>\u6700\u9069\u5316\u5b9f\u88c5\u4f8b\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u5546\u54c1\u4e00\u89a7\u30da\u30fc\u30b8\ndef index\n  @products = Product.includes(\n    :category,\n    variants: [:prices, :stock_items]\n  ).active.page(params[:page])\nend\n\n# \u5728\u5eab\u7ba1\u7406\u753b\u9762\ndef inventory\n  @products = Product.includes(\n    variants: {\n      stock_items: :warehouse\n    }\n  ).low_stock\nend\n\n# \u5546\u54c1\u691c\u7d22\uff08\u4fa1\u683c\u7bc4\u56f2\u6307\u5b9a\uff09\ndef search\n  @products = Product.includes(\n    :category,\n    variants: :prices\n  ).price_between(\n    params[:min_price],\n    params[:max_price]\n  )\nend<\/pre>\n\n\n\n<p>\u30ab\u30b9\u30bf\u30e0\u30b9\u30b3\u30fc\u30d7\u306e\u5b9f\u88c5\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class Product &lt; ApplicationRecord\n  scope :active, -&gt; { where(status: 'active') }\n  scope :low_stock, -&gt; { \n    joins(variants: :stock_items)\n    .group('products.id')\n    .having('SUM(stock_items.quantity) &lt; ?', MINIMUM_STOCK)\n  }\n\n  scope :price_between, -&gt;(min, max) {\n    joins(variants: :prices)\n    .where(prices: { amount: min..max })\n    .distinct\n  }\nend<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-14\">SNS\u30a2\u30d7\u30ea\u3067\u306e\u30e6\u30fc\u30b6\u30fc\u3068\u6295\u7a3f\u306e\u95a2\u9023\u4ed8\u3051<\/h3>\n\n\n\n<p>SNS\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3067\u306f\u3001\u30e6\u30fc\u30b6\u30fc\u3001\u6295\u7a3f\u3001\u30d5\u30a9\u30ed\u30fc\u95a2\u4fc2\u3001\u3044\u3044\u306d\u306a\u3069\u3001\u8907\u96d1\u306a\u95a2\u9023\u3092\u6271\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<p>\u30e2\u30c7\u30eb\u69cb\u6210\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class User &lt; ApplicationRecord\n  has_many :posts\n  has_many :likes\n  has_many :comments\n  has_many :followings\n  has_many :followers, through: :followings\nend\n\nclass Post &lt; ApplicationRecord\n  belongs_to :user\n  has_many :likes\n  has_many :comments\n  has_many :shares\nend\n\nclass Following &lt; ApplicationRecord\n  belongs_to :follower, class_name: 'User'\n  belongs_to :followed, class_name: 'User'\nend<\/pre>\n\n\n\n<p>\u52b9\u7387\u7684\u306a\u30d5\u30a3\u30fc\u30c9\u5b9f\u88c5\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u30bf\u30a4\u30e0\u30e9\u30a4\u30f3\u8868\u793a\ndef timeline\n  @posts = Post.includes(\n    :user,\n    likes: :user,\n    comments: [:user, :replies]\n  ).where(\n    user_id: current_user.following_ids\n  ).recent.page(params[:page])\nend\n\n# \u30d7\u30ed\u30d5\u30a3\u30fc\u30eb\u30da\u30fc\u30b8\ndef profile\n  @user = User.includes(\n    :followers,\n    :following,\n    posts: [:likes, :comments]\n  ).find(params[:id])\nend\n\n# \u901a\u77e5\u6a5f\u80fd\ndef notifications\n  @activities = Activity.includes(\n    trackable: [:user, :comments],\n    recipient: :profile\n  ).where(\n    recipient: current_user\n  ).recent\nend<\/pre>\n\n\n\n<p>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u30c6\u30af\u30cb\u30c3\u30af\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30ab\u30a6\u30f3\u30bf\u30fc\u30ad\u30e3\u30c3\u30b7\u30e5\u306e\u5229\u7528<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class Post &lt; ApplicationRecord\n  belongs_to :user, counter_cache: true\n  has_many :likes, counter_cache: true\nend<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li>\u90e8\u5206\u7684\u306a\u30c7\u30fc\u30bf\u8aad\u307f\u8fbc\u307f<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u6700\u521d\u306f\u6982\u8981\u60c5\u5831\u306e\u307f\u8aad\u307f\u8fbc\u307f\n@posts = Post.includes(:user).recent\n\n# \u8a73\u7d30\u8868\u793a\u6642\u306b\u8ffd\u52a0\u30c7\u30fc\u30bf\u3092\u8aad\u307f\u8fbc\u307f\n@post = Post.includes(\n  comments: [:user, :likes],\n  likes: :user\n).find(params[:id])<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list\">\n<li>\u30d0\u30c3\u30c1\u51e6\u7406\u3067\u306e\u6700\u9069\u5316<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u30d5\u30a9\u30ed\u30ef\u30fc\u3078\u306e\u4e00\u62ec\u901a\u77e5\nUser.includes(:followers)\n    .find_each do |user|\n  user.followers.each do |follower|\n    NotificationWorker.perform_async(\n      follower.id,\n      user.id,\n      'new_post'\n    )\n  end\nend<\/pre>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u5b9f\u88c5\u4f8b\u306f\u3001\u5b9f\u969b\u306e\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u958b\u767a\u3067\u76f4\u9762\u3059\u308b\u5178\u578b\u7684\u306a\u30b7\u30ca\u30ea\u30aa\u306b\u57fa\u3065\u3044\u3066\u3044\u307e\u3059\u3002\u5404\u30b1\u30fc\u30b9\u3067\u9069\u5207\u306bincludes\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u5927\u5e45\u306b\u6539\u5584\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-15\">includes\u30e1\u30bd\u30c3\u30c9\u306e\u30c7\u30d0\u30c3\u30b0\u3068\u30c8\u30e9\u30d6\u30eb\u30b7\u30e5\u30fc\u30c6\u30a3\u30f3\u30b0<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-16\">\u3088\u304f\u3042\u308b\u5b9f\u88c5\u30df\u30b9\u3068\u305d\u306e\u89e3\u6c7a\u65b9\u6cd5<\/h3>\n\n\n\n<p>includes\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3059\u308b\u969b\u306b\u3088\u304f\u767a\u751f\u3059\u308b\u554f\u984c\u3068\u305d\u306e\u89e3\u6c7a\u65b9\u6cd5\u3092\u89e3\u8aac\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>N+1\u30af\u30a8\u30ea\u304c\u89e3\u6d88\u3055\u308c\u306a\u3044<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u554f\u984c\u306e\u3042\u308b\u30b3\u30fc\u30c9\nclass PostsController &lt; ApplicationController\n  def index\n    @posts = Post.includes(:author)\n    # \u554f\u984c\uff1a\u8457\u8005\u306e\u56fd\u60c5\u5831\u3082\u5fc5\u8981\u3060\u304c\u3001includes\u306b\u542b\u307e\u308c\u3066\u3044\u306a\u3044\n    @posts.each do |post|\n      puts post.author.country.name  # N+1\u30af\u30a8\u30ea\u767a\u751f\uff01\n    end\n  end\nend\n\n# \u89e3\u6c7a\u7b56\nclass PostsController &lt; ApplicationController\n  def index\n    @posts = Post.includes(author: :country)\n    @posts.each do |post|\n      puts post.author.country.name  # N+1\u554f\u984c\u89e3\u6d88\n    end\n  end\nend<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li>JOIN\u53e5\u3067\u306e\u6761\u4ef6\u6307\u5b9a\u30a8\u30e9\u30fc<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u554f\u984c\u306e\u3042\u308b\u30b3\u30fc\u30c9\n@posts = Post.includes(:comments)\n            .where('comments.status = ?', 'approved')  # \u30a8\u30e9\u30fc\u767a\u751f\n\n# \u89e3\u6c7a\u7b56\n@posts = Post.includes(:comments)\n            .where('comments.status = ?', 'approved')\n            .references(:comments)  # references\u8ffd\u52a0\u3067\u89e3\u6c7a<\/pre>\n\n\n\n<p>\u3088\u304f\u3042\u308b\u30a8\u30e9\u30fc\u3068\u89e3\u6c7a\u7b56\uff1a<\/p>\n\n\n<div id=\"id-b6fdf45b-59e6-452c-9187-0eeb5d963752\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u30a8\u30e9\u30fc<\/th><th>\u539f\u56e0<\/th><th>\u89e3\u6c7a\u7b56<\/th><\/tr><\/thead><tbody><tr><td>AssociationNotFoundError<\/td><td>\u95a2\u9023\u540d\u306e\u8aa4\u308a<\/td><td>\u30e2\u30c7\u30eb\u306e\u95a2\u9023\u5b9a\u7fa9\u3092\u78ba\u8a8d<\/td><\/tr><tr><td>EagerLoadPolymorphicError<\/td><td>\u30dd\u30ea\u30e2\u30fc\u30d5\u30a3\u30c3\u30af\u95a2\u9023\u306e\u8aa4\u3063\u305f\u6307\u5b9a<\/td><td>\u6b63\u3057\u3044\u95a2\u9023\u6307\u5b9a\u65b9\u6cd5\u3092\u4f7f\u7528<\/td><\/tr><tr><td>references\u306e\u6b20\u843d<\/td><td>JOIN\u6761\u4ef6\u3067\u306e\u30c6\u30fc\u30d6\u30eb\u53c2\u7167\u30a8\u30e9\u30fc<\/td><td>references\u30e1\u30bd\u30c3\u30c9\u3092\u8ffd\u52a0<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<h3 class=\"wp-block-heading\" id=\"i-17\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u30e2\u30cb\u30bf\u30ea\u30f3\u30b0\u306e\u65b9\u6cd5<\/h3>\n\n\n\n<p>Rails\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3067includes\u306e\u52b9\u679c\u3092\u6e2c\u5b9a\u30fb\u30e2\u30cb\u30bf\u30ea\u30f3\u30b0\u3059\u308b\u65b9\u6cd5\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30ed\u30b0\u306e\u6d3b\u7528<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># config\/environments\/development.rb\nconfig.active_record.verbose_query_logs = true\n\n# \u5b9f\u884c\u3055\u308c\u308bSQL\u30af\u30a8\u30ea\u306e\u78ba\u8a8d\n# log\/development.log\u306e\u51fa\u529b\u4f8b\uff1a\n# Post Load (0.6ms)  SELECT \"posts\".* FROM \"posts\"\n# Author Load (0.4ms)  SELECT \"authors\".* WHERE \"authors\".\"id\" IN (1, 2, 3)<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li>bullet gem\u306e\u5c0e\u5165<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># Gemfile\ngroup :development do\n  gem 'bullet'\nend\n\n# config\/environments\/development.rb\nconfig.after_initialize do\n  Bullet.enable = true\n  Bullet.alert = true\n  Bullet.rails_logger = true\nend<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list\">\n<li>rack-mini-profiler\u306e\u6d3b\u7528<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># Gemfile\ngem 'rack-mini-profiler'\n\n# \u7279\u5b9a\u306e\u30af\u30a8\u30ea\u306e\u30d7\u30ed\u30d5\u30a1\u30a4\u30ea\u30f3\u30b0\ndef index\n  Rack::MiniProfiler.step('Posts with includes') do\n    @posts = Post.includes(:author, :comments)\n  end\nend<\/pre>\n\n\n\n<p>\u30e2\u30cb\u30bf\u30ea\u30f3\u30b0\u30dd\u30a4\u30f3\u30c8\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u30af\u30a8\u30ea\u5b9f\u884c\u56de\u6570<\/li>\n\n\n\n<li>\u30af\u30a8\u30ea\u5b9f\u884c\u6642\u9593<\/li>\n\n\n\n<li>\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf<\/li>\n\n\n\n<li>\u30ec\u30b9\u30dd\u30f3\u30b9\u30bf\u30a4\u30e0<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-18\">SQL\u30af\u30a8\u30ea\u306e\u6700\u9069\u5316\u30c6\u30af\u30cb\u30c3\u30af<\/h3>\n\n\n\n<p>includes\u30e1\u30bd\u30c3\u30c9\u304c\u751f\u6210\u3059\u308bSQL\u30af\u30a8\u30ea\u3092\u6700\u9069\u5316\u3059\u308b\u30c6\u30af\u30cb\u30c3\u30af\u3092\u89e3\u8aac\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u306e\u9069\u5207\u306a\u8a2d\u5b9a<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u30de\u30a4\u30b0\u30ec\u30fc\u30b7\u30e7\u30f3\u30d5\u30a1\u30a4\u30eb\u3067\u306e\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u8a2d\u5b9a\nclass AddIndexesToPosts &lt; ActiveRecord::Migration[6.1]\n  def change\n    add_index :posts, :author_id\n    add_index :posts, [:status, :created_at]\n  end\nend<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li>\u8907\u96d1\u306a\u30af\u30a8\u30ea\u306e\u6700\u9069\u5316<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u6700\u9069\u5316\u524d\n@posts = Post.includes(:author, :comments)\n            .where('authors.name LIKE ?', '%John%')\n            .where('comments.created_at &gt; ?', 1.week.ago)\n            .references(:authors, :comments)\n\n# \u6700\u9069\u5316\u5f8c\n@posts = Post.joins(:author, :comments)\n            .includes(:author, :comments)\n            .where(authors: { name: '%John%' })\n            .where(comments: { created_at: 1.week.ago.. })\n            .distinct<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list\">\n<li>\u30af\u30a8\u30ea\u306e\u30c1\u30e5\u30fc\u30cb\u30f3\u30b0\u4f8b<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u5927\u91cf\u30c7\u30fc\u30bf\u306e\u52b9\u7387\u7684\u306a\u51e6\u7406\nPost.includes(:comments)\n    .find_each(batch_size: 100) do |post|\n  # \u30d0\u30c3\u30c1\u51e6\u7406\nend\n\n# \u5fc5\u8981\u306a\u30ab\u30e9\u30e0\u306e\u307f\u3092\u9078\u629e\nPost.includes(:author)\n    .select('posts.id, posts.title, authors.name')\n    .references(:authors)<\/pre>\n\n\n\n<p>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6539\u5584\u306e\u30c1\u30a7\u30c3\u30af\u30ea\u30b9\u30c8\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u306e\u5b9f\u884c\u8a08\u753b\u306e\u78ba\u8a8d<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>EXPLAIN ANALYZE\u306e\u6d3b\u7528<\/li>\n\n\n\n<li>\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u306e\u4f7f\u7528\u72b6\u6cc1\u78ba\u8a8d<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u306e\u6700\u9069\u5316<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5fc5\u8981\u6700\u5c0f\u9650\u306e\u30c7\u30fc\u30bf\u53d6\u5f97<\/li>\n\n\n\n<li>\u30da\u30fc\u30b8\u30cd\u30fc\u30b7\u30e7\u30f3\u306e\u9069\u5207\u306a\u5b9f\u88c5<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30ad\u30e3\u30c3\u30b7\u30e5\u306e\u6d3b\u7528<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\"># \u30ad\u30e3\u30c3\u30b7\u30e5\u306e\u5b9f\u88c5\u4f8b\nclass Post &lt; ApplicationRecord\n  after_touch :touch_associations\n\n  private\n\n  def touch_associations\n    author.touch\n    comments.each(&amp;:touch)\n  end\nend<\/pre>\n\n\n\n<p>\u30c8\u30e9\u30d6\u30eb\u30b7\u30e5\u30fc\u30c6\u30a3\u30f3\u30b0\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u6bb5\u968e\u7684\u306a\u30c7\u30d0\u30c3\u30b0<\/li>\n\n\n\n<li>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u30e1\u30c8\u30ea\u30af\u30b9\u306e\u7d99\u7d9a\u7684\u306a\u30e2\u30cb\u30bf\u30ea\u30f3\u30b0<\/li>\n\n\n\n<li>\u5b9f\u74b0\u5883\u306b\u8fd1\u3044\u6761\u4ef6\u3067\u306e\u30c6\u30b9\u30c8\u5b9f\u65bd<\/li>\n\n\n\n<li>\u5b9a\u671f\u7684\u306a\u30af\u30a8\u30ea\u306e\u898b\u76f4\u3057\u3068\u30ea\u30d5\u30a1\u30af\u30bf\u30ea\u30f3\u30b0<\/li>\n<\/ol>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-19\">\u767a\u5c55\u7684\u306a\u4f7f\u7528\u65b9\u6cd5\u3068\u30c6\u30af\u30cb\u30c3\u30af<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-20\">\u6761\u4ef6\u4ed8\u304d\u3067\u306e\u95a2\u9023\u30c7\u30fc\u30bf\u306e\u8aad\u307f\u8fbc\u307f<\/h3>\n\n\n\n<p>\u6761\u4ef6\u4ed8\u304d\u3067\u306e\u95a2\u9023\u30c7\u30fc\u30bf\u8aad\u307f\u8fbc\u307f\u306f\u3001\u5fc5\u8981\u306a\u30c7\u30fc\u30bf\u306e\u307f\u3092\u52b9\u7387\u7684\u306b\u53d6\u5f97\u3059\u308b\u9ad8\u5ea6\u306a\u30c6\u30af\u30cb\u30c3\u30af\u3067\u3059\u3002<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>where\u6761\u4ef6\u306b\u3088\u308b\u95a2\u9023\u30c7\u30fc\u30bf\u306e\u30d5\u30a3\u30eb\u30bf\u30ea\u30f3\u30b0<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class Post &lt; ApplicationRecord\n  has_many :comments\n  has_many :recent_comments, -&gt; { where('created_at &gt; ?', 1.week.ago) }, \n           class_name: 'Comment'\nend\n\n# \u5b9f\u88c5\u4f8b\n@posts = Post.includes(:recent_comments)\n            .where(status: 'published')<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li>\u52d5\u7684\u306a\u6761\u4ef6\u3067\u306e\u8aad\u307f\u8fbc\u307f<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class Product &lt; ApplicationRecord\n  has_many :variants\n  has_many :active_variants, -&gt; { where(status: 'active') },\n           class_name: 'Variant'\n\n  # \u5728\u5eab\u6570\u306b\u3088\u308b\u52d5\u7684\u30d5\u30a3\u30eb\u30bf\u30ea\u30f3\u30b0\n  def variants_with_stock(minimum_stock)\n    variants.includes(:stock_items)\n           .where('stock_items.quantity &gt;= ?', minimum_stock)\n           .references(:stock_items)\n  end\nend\n\n# \u4f7f\u7528\u4f8b\n@product = Product.includes(:active_variants)\n                 .find(params[:id])\n@variants_in_stock = @product.variants_with_stock(10)<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list\">\n<li>\u8907\u96d1\u306a\u6761\u4ef6\u306e\u7d44\u307f\u5408\u308f\u305b<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class Order &lt; ApplicationRecord\n  has_many :line_items\n  has_many :products, through: :line_items\n\n  # \u7279\u5b9a\u6761\u4ef6\u306e\u5546\u54c1\u306e\u307f\u3092\u542b\u3080\u6ce8\u6587\u3092\u691c\u7d22\n  scope :with_special_products, -&gt; {\n    includes(line_items: :product)\n      .where(products: { \n        special_offer: true,\n        available: true \n      })\n      .references(:products)\n  }\nend<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-21\">\u30ab\u30b9\u30bf\u30e0SQL\u3092\u4f7f\u7528\u3057\u305f\u6700\u9069\u5316<\/h3>\n\n\n\n<p>\u3088\u308a\u8907\u96d1\u306a\u30b1\u30fc\u30b9\u3067\u306f\u3001\u30ab\u30b9\u30bf\u30e0SQL\u3092\u4f7f\u7528\u3057\u3066\u6700\u9069\u5316\u3092\u884c\u3046\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u751fSQL\u306e\u4f7f\u7528<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class User &lt; ApplicationRecord\n  has_many :posts\n\n  def self.with_post_stats\n    select('users.*, COUNT(posts.id) as posts_count, ' \\\n           'MAX(posts.created_at) as latest_post_date')\n      .joins('LEFT JOIN posts ON posts.user_id = users.id')\n      .group('users.id')\n  end\nend\n\n# \u4f7f\u7528\u4f8b\n@active_users = User.with_post_stats\n                   .having('COUNT(posts.id) &gt; ?', 5)<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li>\u30b5\u30d6\u30af\u30a8\u30ea\u306e\u6d3b\u7528<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class Post &lt; ApplicationRecord\n  belongs_to :author\n  has_many :comments\n\n  # \u4eba\u6c17\u306e\u6295\u7a3f\u3092\u53d6\u5f97\n  scope :popular, -&gt; {\n    subquery = Comment.select('post_id, COUNT(*) as comment_count')\n                     .group(:post_id)\n                     .to_sql\n\n    joins(\"JOIN (#{subquery}) AS comment_counts ON posts.id = comment_counts.post_id\")\n      .where('comment_counts.comment_count &gt; ?', 10)\n      .includes(:author)\n  }\nend<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list\">\n<li>Window\u95a2\u6570\u306e\u5229\u7528<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class Post &lt; ApplicationRecord\n  # \u8457\u8005\u3054\u3068\u306e\u4e0a\u4f4dN\u4ef6\u306e\u6295\u7a3f\u3092\u53d6\u5f97\n  def self.top_by_author(limit_per_author = 5)\n    find_by_sql([\"\n      WITH ranked_posts AS (\n        SELECT posts.*,\n               ROW_NUMBER() OVER (\n                 PARTITION BY author_id\n                 ORDER BY views_count DESC\n               ) as rank\n        FROM posts\n      )\n      SELECT *\n      FROM ranked_posts\n      WHERE rank &lt;= ?\n    \", limit_per_author])\n  end\nend<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-22\">\u5927\u898f\u6a21\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3067\u306e\u5b9f\u88c5\u30d1\u30bf\u30fc\u30f3<\/h3>\n\n\n\n<p>\u5927\u898f\u6a21\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3067\u306f\u3001\u52b9\u7387\u7684\u306a\u30c7\u30fc\u30bf\u8aad\u307f\u8fbc\u307f\u304c\u3088\u308a\u91cd\u8981\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30af\u30a8\u30ea\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d1\u30bf\u30fc\u30f3<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class PostQuery\n  def initialize(relation = Post.all)\n    @relation = relation\n  end\n\n  def published\n    @relation.where(status: 'published')\n  end\n\n  def with_complete_data\n    @relation.includes(\n      :author,\n      :categories,\n      comments: [:user, :reactions]\n    )\n  end\n\n  def popular\n    @relation.where('views_count &gt; ?', 1000)\n  end\n\n  def recent(days = 7)\n    @relation.where('created_at &gt; ?', days.days.ago)\n  end\n\n  def result\n    @relation\n  end\nend\n\n# \u4f7f\u7528\u4f8b\nquery = PostQuery.new\n@posts = query.published\n              .with_complete_data\n              .popular\n              .recent(30)\n              .result<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li>\u30b5\u30fc\u30d3\u30b9\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30d1\u30bf\u30fc\u30f3<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class Posts::FeedGenerator\n  def initialize(user)\n    @user = user\n  end\n\n  def generate\n    collect_followed_posts\n    include_related_data\n    apply_filters\n    sort_and_paginate\n  end\n\n  private\n\n  def collect_followed_posts\n    @posts = Post.where(\n      author_id: @user.following_ids\n    )\n  end\n\n  def include_related_data\n    @posts = @posts.includes(\n      :author,\n      comments: :user,\n      likes: :user\n    )\n  end\n\n  def apply_filters\n    @posts = @posts.where(status: 'published')\n                  .where('created_at &gt; ?', 1.week.ago)\n  end\n\n  def sort_and_paginate\n    @posts.order(created_at: :desc)\n          .page(params[:page])\n  end\nend<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list\">\n<li>\u30ad\u30e3\u30c3\u30b7\u30e5\u6226\u7565\u306e\u5b9f\u88c5<\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class CacheableQuery\n  def initialize(base_relation)\n    @relation = base_relation\n  end\n\n  def fetch_with_cache(cache_key, expires_in: 1.hour)\n    Rails.cache.fetch(cache_key, expires_in: expires_in) do\n      @relation.to_a\n    end\n  end\nend\n\n# \u4f7f\u7528\u4f8b\nclass DashboardController &lt; ApplicationController\n  def index\n    query = CacheableQuery.new(\n      Post.includes(:author, :categories)\n          .recent\n          .published\n    )\n\n    @posts = query.fetch_with_cache(\n      \"dashboard_posts_#{current_user.id}\",\n      expires_in: 15.minutes\n    )\n  end\nend<\/pre>\n\n\n\n<p>\u5b9f\u88c5\u6642\u306e\u6ce8\u610f\u70b9\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u306e\u7ba1\u7406<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5927\u898f\u6a21\u30c7\u30fc\u30bf\u30bb\u30c3\u30c8\u306e\u5206\u5272\u51e6\u7406<\/li>\n\n\n\n<li>\u5fc5\u8981\u6700\u5c0f\u9650\u306e\u30c7\u30fc\u30bf\u53d6\u5f97<\/li>\n\n\n\n<li>\u9069\u5207\u306a\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u8a2d\u5b9a<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u30e2\u30cb\u30bf\u30ea\u30f3\u30b0<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>APM\u30c4\u30fc\u30eb\u306e\u6d3b\u7528<\/li>\n\n\n\n<li>\u30af\u30a8\u30ea\u30ed\u30b0\u306e\u5b9a\u671f\u7684\u306a\u78ba\u8a8d<\/li>\n\n\n\n<li>\u30dc\u30c8\u30eb\u30cd\u30c3\u30af\u306e\u65e9\u671f\u767a\u898b<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u30b9\u30b1\u30fc\u30e9\u30d3\u30ea\u30c6\u30a3\u306e\u8003\u616e<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u8aad\u307f\u53d6\u308a\/\u66f8\u304d\u8fbc\u307f\u306e\u5206\u96e2<\/li>\n\n\n\n<li>\u30ad\u30e3\u30c3\u30b7\u30e5\u6226\u7565\u306e\u6700\u9069\u5316<\/li>\n\n\n\n<li>\u30d0\u30c3\u30c1\u51e6\u7406\u306e\u9069\u5207\u306a\u5b9f\u88c5<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Warning: Undefined array key &#8220;is_admin&#8221; in \/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/ &#8230; <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":{"0":"post-1406","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-ruby","7":"nothumb"},"_links":{"self":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/1406","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1406"}],"version-history":[{"count":2,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/1406\/revisions"}],"predecessor-version":[{"id":3486,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/1406\/revisions\/3486"}],"wp:attachment":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1406"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1406"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1406"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}