{"id":21546,"date":"2024-01-02T11:16:24","date_gmt":"2024-01-02T11:16:24","guid":{"rendered":"https:\/\/server.hk\/blog\/21546\/"},"modified":"2024-11-14T10:30:57","modified_gmt":"2024-11-14T02:30:57","slug":"mongodb-glossary-covered-query","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/21546\/","title":{"rendered":"MongoDB \u8a5e\u5f59\u8868 &#8211; \u8986\u84cb\u67e5\u8a62"},"content":{"rendered":"<h1 id=\"mongodb-glossary-covered-query-VKENYmXlHI\">MongoDB \u8a5e\u5f59\u8868 &#8211; \u8986\u84cb\u67e5\u8a62<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7684\u4e16\u754c\u4e2d\uff0cMongoDB \u56e0\u5176\u9748\u6d3b\u6027\u3001\u53ef\u64f4\u5c55\u6027\u548c\u6027\u80fd\u800c\u53d7\u5230\u5ee3\u6cdb\u6b61\u8fce\u3002\u4f5c\u70ba\u4e00\u500b NoSQL \u6578\u64da\u5eab\uff0cMongoDB \u63d0\u4f9b\u4e86\u591a\u7a2e\u529f\u80fd\uff0c\u8b93\u5b83\u6210\u70ba\u8a31\u591a\u958b\u767c\u8005\u548c\u4f01\u696d\u7684\u9996\u9078\u3002\u5176\u4e2d\u4e00\u9805\u91cd\u8981\u529f\u80fd\u662f\u8986\u84cb\u67e5\u8a62\uff0c\u5b83\u5728\u512a\u5316\u67e5\u8a62\u6027\u80fd\u65b9\u9762\u767c\u63ee\u8457\u95dc\u9375\u4f5c\u7528\u3002\u5728\u672c\u6587\u4e2d\uff0c\u6211\u5011\u5c07\u63a2\u8a0e MongoDB \u4e2d\u8986\u84cb\u67e5\u8a62\u7684\u6982\u5ff5\uff0c\u4e26\u4e86\u89e3\u5b83\u5011\u5982\u4f55\u63d0\u9ad8\u6578\u64da\u5eab\u64cd\u4f5c\u7684\u6548\u7387\u3002<\/p>\n<h2 id=\"understanding-covered-queries-VKENYmXlHI\">\u4e86\u89e3\u8986\u84cb\u67e5\u8a62<\/h2>\n<p>\u5728 MongoDB \u4e2d\uff0c\u8986\u84cb\u67e5\u8a62\u662f\u6307\u6240\u6709\u67e5\u8a62\u6240\u9700\u7684\u5b57\u6bb5\u90fd\u5b58\u5728\u65bc\u7d22\u5f15\u4e2d\u7684\u67e5\u8a62\u3002\u63db\u53e5\u8a71\u8aaa\uff0cMongoDB \u53ef\u4ee5\u50c5\u4f7f\u7528\u7d22\u5f15\u4f86\u6eff\u8db3\u67e5\u8a62\uff0c\u800c\u4e0d\u9700\u8981\u8a2a\u554f\u96c6\u5408\u4e2d\u7684\u5be6\u969b\u6587\u6a94\u3002\u9019\u7a2e\u512a\u5316\u6280\u8853\u53ef\u4ee5\u901a\u904e\u6e1b\u5c11\u78c1\u789f I\/O \u548c\u5167\u5b58\u4f7f\u7528\u986f\u8457\u63d0\u9ad8\u8b80\u53d6\u64cd\u4f5c\u7684\u6027\u80fd\u3002<\/p>\n<p>\u7576\u67e5\u8a62\u88ab\u8986\u84cb\u6642\uff0cMongoDB \u53ef\u4ee5\u76f4\u63a5\u5f9e\u7d22\u5f15\u4e2d\u6aa2\u7d22\u6240\u9700\u6578\u64da\uff0c\u800c\u7121\u9700\u5c07\u6574\u500b\u6587\u6a94\u52a0\u8f09\u5230\u5167\u5b58\u4e2d\u3002\u9019\u5c0e\u81f4\u67e5\u8a62\u57f7\u884c\u901f\u5ea6\u66f4\u5feb\uff0c\u8cc7\u6e90\u6d88\u8017\u6e1b\u5c11\uff0c\u4f7f\u8986\u84cb\u67e5\u8a62\u6210\u70ba\u512a\u5316\u6578\u64da\u5eab\u6027\u80fd\u7684\u91cd\u8981\u5de5\u5177\u3002<\/p>\n<h2 id=\"benefits-of-covered-queries-VKENYmXlHI\">\u8986\u84cb\u67e5\u8a62\u7684\u597d\u8655<\/h2>\n<p>\u8986\u84cb\u67e5\u8a62\u76f8\u8f03\u65bc\u666e\u901a\u67e5\u8a62\u5728 MongoDB \u4e2d\u63d0\u4f9b\u4e86\u5e7e\u500b\u512a\u52e2\uff1a<\/p>\n<ul>\n<li><strong>\u6027\u80fd\u63d0\u5347\uff1a<\/strong>\u901a\u904e\u907f\u514d\u8a2a\u554f\u5be6\u969b\u6587\u6a94\uff0c\u8986\u84cb\u67e5\u8a62\u6e1b\u5c11\u4e86\u78c1\u789f I\/O \u548c\u5167\u5b58\u4f7f\u7528\uff0c\u5f9e\u800c\u52a0\u5feb\u4e86\u67e5\u8a62\u57f7\u884c\u901f\u5ea6\u3002<\/li>\n<li><strong>\u6e1b\u5c11\u7db2\u7d61\u6d41\u91cf\uff1a<\/strong>\u7531\u65bc MongoDB \u76f4\u63a5\u5f9e\u7d22\u5f15\u4e2d\u6aa2\u7d22\u6240\u9700\u6578\u64da\uff0c\u6578\u64da\u5eab\u670d\u52d9\u5668\u8207\u5ba2\u6236\u7aef\u4e4b\u9593\u7684\u6578\u64da\u50b3\u8f38\u91cf\u6e1b\u5c11\uff0c\u5c0e\u81f4\u7db2\u7d61\u6d41\u91cf\u964d\u4f4e\u3002<\/li>\n<li><strong>\u512a\u5316\u7d22\u5f15\u4f7f\u7528\uff1a<\/strong>\u8986\u84cb\u67e5\u8a62\u901a\u904e\u78ba\u4fdd\u6240\u6709\u5fc5\u8981\u5b57\u6bb5\u90fd\u5b58\u5728\u65bc\u7d22\u5f15\u4e2d\uff0c\u9f13\u52f5\u4f7f\u7528\u7d22\u5f15\u3002\u9019\u4fc3\u9032\u4e86\u7d22\u5f15\u7684\u9ad8\u6548\u5229\u7528\uff0c\u4e26\u80fd\u6539\u5584\u6574\u9ad4\u67e5\u8a62\u6027\u80fd\u3002<\/li>\n<\/ul>\n<h2 id=\"creating-covered-queries-VKENYmXlHI\">\u5275\u5efa\u8986\u84cb\u67e5\u8a62<\/h2>\n<p>\u8981\u5728 MongoDB \u4e2d\u5275\u5efa\u8986\u84cb\u67e5\u8a62\uff0c\u60a8\u9700\u8981\u78ba\u4fdd\u67e5\u8a62\u6240\u9700\u7684\u6240\u6709\u5b57\u6bb5\u90fd\u5305\u542b\u5728\u7d22\u5f15\u4e2d\u3002\u9019\u610f\u5473\u8457\u7d22\u5f15\u61c9\u8a72\u8986\u84cb\u67e5\u8a62\u7684\u904e\u6ffe\u689d\u4ef6\u548c\u8981\u5728\u7d50\u679c\u96c6\u4e2d\u8fd4\u56de\u7684\u5b57\u6bb5\u3002<\/p>\n<p>\u4f8b\u5982\uff0c\u8003\u616e\u4e00\u500b\u5305\u542b\u5ba2\u6236\u6587\u6a94\u7684\u96c6\u5408\uff0c\u5176\u5b57\u6bb5\u5305\u62ec\u59d3\u540d\u3001\u96fb\u5b50\u90f5\u4ef6\u3001\u5e74\u9f61\u548c\u5730\u5740\u3002\u8981\u5275\u5efa\u4e00\u500b\u67e5\u8a62\u4ee5\u6aa2\u7d22\u6240\u6709 25 \u6b72\u7684\u5ba2\u6236\u59d3\u540d\uff0c\u60a8\u53ef\u4ee5\u5728\u5e74\u9f61\u5b57\u6bb5\u4e0a\u5275\u5efa\u7d22\u5f15\u3002\u9019\u500b\u7d22\u5f15\u5c07\u8986\u84cb\u904e\u6ffe\u689d\u4ef6\uff08\u5e74\u9f61\uff1a25\uff09\u548c\u8981\u8fd4\u56de\u7684\u5b57\u6bb5\uff08\u59d3\u540d\uff09\u3002<\/p>\n<pre><code>db.customers.createIndex({ age: 1 })\r\ndb.customers.find({ age: 25 }, { name: 1, _id: 0 }).explain()<\/code><\/pre>\n<p><code>explain()<\/code> \u65b9\u6cd5\u63d0\u4f9b\u6709\u95dc\u67e5\u8a62\u57f7\u884c\u7684\u4fe1\u606f\uff0c\u5305\u62ec\u662f\u5426\u88ab\u8986\u84cb\u3002\u5728\u8f38\u51fa\u4e2d\uff0c\u5982\u679c\u60a8\u770b\u5230 <code>\"stage\": \"IXSCAN\"<\/code> \u548c <code>\"isCovered\": true<\/code>\uff0c\u9019\u8868\u793a\u67e5\u8a62\u662f\u8986\u84cb\u7684\u3002<\/p>\n<h2 id=\"conclusion-VKENYmXlHI\">\u7d50\u8ad6<\/h2>\n<p>\u8986\u84cb\u67e5\u8a62\u662f MongoDB \u4e2d\u4e00\u7a2e\u5f37\u5927\u7684\u512a\u5316\u6280\u8853\uff0c\u53ef\u4ee5\u986f\u8457\u63d0\u5347\u8b80\u53d6\u64cd\u4f5c\u7684\u6027\u80fd\u3002\u901a\u904e\u5229\u7528\u7d22\u5f15\u76f4\u63a5\u6aa2\u7d22\u6578\u64da\uff0c\u8986\u84cb\u67e5\u8a62\u6700\u5c0f\u5316\u78c1\u789f I\/O\u3001\u6e1b\u5c11\u5167\u5b58\u4f7f\u7528\u4e26\u63d0\u9ad8\u6574\u9ad4\u67e5\u8a62\u57f7\u884c\u901f\u5ea6\u3002\u4e86\u89e3\u548c\u5229\u7528\u8986\u84cb\u67e5\u8a62\u53ef\u4ee5\u5e6b\u52a9\u60a8\u767c\u63ee MongoDB \u7684\u5168\u90e8\u6f5b\u529b\uff0c\u78ba\u4fdd\u9ad8\u6548\u4e14\u53ef\u64f4\u5c55\u7684\u6578\u64da\u5eab\u64cd\u4f5c\u3002<\/p>\n<h3 id=\"summary-VKENYmXlHI\">\u6458\u8981\uff1a<\/h3>\n<p>\u5728\u672c\u6587\u4e2d\uff0c\u6211\u5011\u63a2\u8a0e\u4e86 MongoDB \u4e2d\u8986\u84cb\u67e5\u8a62\u7684\u6982\u5ff5\u3002\u8986\u84cb\u67e5\u8a62\u662f\u6240\u6709\u5fc5\u8981\u5b57\u6bb5\u90fd\u5b58\u5728\u65bc\u7d22\u5f15\u4e2d\u7684\u67e5\u8a62\uff0c\u5141\u8a31 MongoDB \u50c5\u4f7f\u7528\u7d22\u5f15\u4f86\u6eff\u8db3\u67e5\u8a62\uff0c\u800c\u7121\u9700\u8a2a\u554f\u5be6\u969b\u6587\u6a94\u3002\u9019\u7a2e\u512a\u5316\u6280\u8853\u6539\u5584\u4e86\u67e5\u8a62\u6027\u80fd\u3001\u6e1b\u5c11\u4e86\u7db2\u7d61\u6d41\u91cf\u4e26\u512a\u5316\u4e86\u7d22\u5f15\u4f7f\u7528\u3002\u901a\u904e\u5275\u5efa\u8986\u84cb\u904e\u6ffe\u689d\u4ef6\u548c\u8981\u8fd4\u56de\u5b57\u6bb5\u7684\u7d22\u5f15\uff0c\u60a8\u53ef\u4ee5\u5229\u7528\u8986\u84cb\u67e5\u8a62\u4f86\u63d0\u9ad8 MongoDB \u6578\u64da\u5eab\u64cd\u4f5c\u7684\u6548\u7387\u3002\u6b32\u4e86\u89e3\u66f4\u591a\u6709\u95dc MongoDB \u53ca\u5176\u529f\u80fd\u7684\u4fe1\u606f\uff0c\u8acb\u8a2a\u554f <a href=\"https:\/\/server.hk\">Server.HK<\/a>\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>MongoDB \u8a5e\u5f59\u8868 &#038;#82&#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4925],"tags":[],"class_list":["post-21546","post","type-post","status-publish","format-standard","hentry","category-4925"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/21546","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=21546"}],"version-history":[{"count":2,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/21546\/revisions"}],"predecessor-version":[{"id":23909,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/21546\/revisions\/23909"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=21546"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=21546"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=21546"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}