{"id":170065,"date":"2024-11-06T20:51:17","date_gmt":"2024-11-06T12:51:17","guid":{"rendered":"https:\/\/server.hk\/cnblog\/170065\/"},"modified":"2024-11-06T20:51:18","modified_gmt":"2024-11-06T12:51:18","slug":"%e4%bd%a0%e6%9c%83%e7%9c%8b-mysql-%e7%9a%84%e5%9f%b7%e8%a1%8c%e8%a8%88%e5%8a%83%ef%bc%88explain%ef%bc%89%e5%97%8e%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/170065\/","title":{"rendered":"\u4f60\u6703\u770b MySQL \u7684\u57f7\u884c\u8a08\u5283\uff08EXPLAIN\uff09\u55ce\uff1f"},"content":{"rendered":"<h1 id=\"%e4%bd%a0%e6%9c%83%e7%9c%8b-mysql-%e7%9a%84%e5%9f%b7%e8%a1%8c%e8%a8%88%e5%8a%83%ef%bc%88explain%ef%bc%89%e5%97%8e%ef%bc%9f-VkvcmAdrYl\">\u4f60\u6703\u770b MySQL \u7684\u57f7\u884c\u8a08\u5283\uff08EXPLAIN\uff09\u55ce\uff1f<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\uff0c\u6027\u80fd\u512a\u5316\u662f\u4e00\u500b\u81f3\u95dc\u91cd\u8981\u7684\u8ab2\u984c\u3002MySQL \u4f5c\u70ba\u4e00\u500b\u6d41\u884c\u7684\u958b\u6e90\u6578\u64da\u5eab\u7cfb\u7d71\uff0c\u63d0\u4f9b\u4e86\u591a\u7a2e\u5de5\u5177\u4f86\u5e6b\u52a9\u958b\u767c\u8005\u548c\u6578\u64da\u5eab\u7ba1\u7406\u54e1\u5206\u6790\u67e5\u8a62\u6027\u80fd\u3002\u5176\u4e2d\uff0c<code>EXPLAIN<\/code> \u662f\u4e00\u500b\u975e\u5e38\u6709\u7528\u7684\u547d\u4ee4\uff0c\u53ef\u4ee5\u5e6b\u52a9\u6211\u5011\u7406\u89e3 MySQL \u5982\u4f55\u57f7\u884c\u67e5\u8a62\uff0c\u5f9e\u800c\u627e\u51fa\u6f5b\u5728\u7684\u6027\u80fd\u74f6\u9838\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%af-explain%ef%bc%9f-VkvcmAdrYl\">\u4ec0\u9ebc\u662f EXPLAIN\uff1f<\/h2>\n<p><code>EXPLAIN<\/code> \u662f\u4e00\u500b SQL \u8a9e\u53e5\uff0c\u7528\u65bc\u986f\u793a MySQL \u5728\u57f7\u884c\u67e5\u8a62\u6642\u7684\u57f7\u884c\u8a08\u5283\u3002\u901a\u904e\u9019\u500b\u547d\u4ee4\uff0c\u6211\u5011\u53ef\u4ee5\u7372\u5f97\u6709\u95dc\u67e5\u8a62\u7684\u8a73\u7d30\u4fe1\u606f\uff0c\u5305\u62ec\u4f7f\u7528\u7684\u7d22\u5f15\u3001\u8868\u7684\u8a2a\u554f\u9806\u5e8f\u3001\u4ee5\u53ca\u6bcf\u500b\u6b65\u9a5f\u7684\u9810\u4f30\u884c\u6578\u7b49\u3002\u9019\u4e9b\u4fe1\u606f\u5c0d\u65bc\u512a\u5316\u67e5\u8a62\u6027\u80fd\u81f3\u95dc\u91cd\u8981\u3002<\/p>\n<h2 id=\"%e5%a6%82%e4%bd%95%e4%bd%bf%e7%94%a8-explain%ef%bc%9f-VkvcmAdrYl\">\u5982\u4f55\u4f7f\u7528 EXPLAIN\uff1f<\/h2>\n<p>\u4f7f\u7528 <code>EXPLAIN<\/code> \u975e\u5e38\u7c21\u55ae\uff0c\u53ea\u9700\u5728\u67e5\u8a62\u8a9e\u53e5\u524d\u52a0\u4e0a <code>EXPLAIN<\/code> \u5373\u53ef\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>EXPLAIN SELECT * FROM users WHERE age &gt; 30;<\/code><\/pre>\n<p>\u57f7\u884c\u4e0a\u8ff0\u547d\u4ee4\u5f8c\uff0cMySQL \u5c07\u8fd4\u56de\u4e00\u500b\u8868\u683c\uff0c\u986f\u793a\u57f7\u884c\u8a08\u5283\u7684\u5404\u500b\u65b9\u9762\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684\u5217\uff1a<\/p>\n<ul>\n<li><strong>id\uff1a<\/strong>\u67e5\u8a62\u7684\u8b58\u5225\u78bc\uff0c\u5c0d\u65bc\u8907\u96dc\u67e5\u8a62\uff0c\u53ef\u80fd\u6703\u6709\u591a\u500b id\u3002<\/li>\n<li><strong>select_type\uff1a<\/strong>\u67e5\u8a62\u7684\u985e\u578b\uff0c\u4f8b\u5982\u7c21\u55ae\u67e5\u8a62\u3001\u806f\u63a5\u67e5\u8a62\u7b49\u3002<\/li>\n<li><strong>table\uff1a<\/strong>\u6b63\u5728\u8a2a\u554f\u7684\u8868\u540d\u3002<\/li>\n<li><strong>type\uff1a<\/strong>\u8a2a\u554f\u985e\u578b\uff0c\u986f\u793a MySQL \u5982\u4f55\u8a2a\u554f\u8868\uff0c\u5f9e\u6700\u4f73\u5230\u6700\u5dee\u7684\u9806\u5e8f\u70ba\uff1asystem\u3001const\u3001eq_ref\u3001ref\u3001range\u3001index\u3001ALL\u3002<\/li>\n<li><strong>possible_keys\uff1a<\/strong>\u53ef\u80fd\u4f7f\u7528\u7684\u7d22\u5f15\u3002<\/li>\n<li><strong>key\uff1a<\/strong>\u5be6\u969b\u4f7f\u7528\u7684\u7d22\u5f15\u3002<\/li>\n<li><strong>rows\uff1a<\/strong>\u9810\u4f30\u9700\u8981\u6383\u63cf\u7684\u884c\u6578\u3002<\/li>\n<li><strong>Extra\uff1a<\/strong>\u984d\u5916\u4fe1\u606f\uff0c\u4f8b\u5982\u662f\u5426\u4f7f\u7528\u4e86\u81e8\u6642\u8868\u6216\u6587\u4ef6\u6392\u5e8f\u3002<\/li>\n<\/ul>\n<h2 id=\"%e8%a7%a3%e8%ae%80-explain-%e7%9a%84%e7%b5%90%e6%9e%9c-VkvcmAdrYl\">\u89e3\u8b80 EXPLAIN \u7684\u7d50\u679c<\/h2>\n<p>\u7406\u89e3 <code>EXPLAIN<\/code> \u7684\u7d50\u679c\u662f\u512a\u5316\u67e5\u8a62\u7684\u95dc\u9375\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684\u60c5\u6cc1\u53ca\u5176\u89e3\u91cb\uff1a<\/p>\n<h3 id=\"1-%e4%bd%bf%e7%94%a8%e4%b8%8d%e7%95%b6%e7%9a%84%e8%a8%aa%e5%95%8f%e9%a1%9e%e5%9e%8b-VkvcmAdrYl\">1. \u4f7f\u7528\u4e0d\u7576\u7684\u8a2a\u554f\u985e\u578b<\/h3>\n<p>\u5982\u679c <strong>type<\/strong> \u5217\u986f\u793a\u70ba <code>ALL<\/code>\uff0c\u9019\u610f\u5473\u8457 MySQL \u5c07\u9032\u884c\u5168\u8868\u6383\u63cf\uff0c\u9019\u901a\u5e38\u662f\u6027\u80fd\u4e0d\u4f73\u7684\u6307\u6a19\u3002\u6b64\u6642\uff0c\u53ef\u4ee5\u8003\u616e\u6dfb\u52a0\u7d22\u5f15\u4f86\u6539\u5584\u67e5\u8a62\u6027\u80fd\u3002<\/p>\n<h3 id=\"2-%e7%b4%a2%e5%bc%95%e6%9c%aa%e8%a2%ab%e4%bd%bf%e7%94%a8-VkvcmAdrYl\">2. \u7d22\u5f15\u672a\u88ab\u4f7f\u7528<\/h3>\n<p>\u5982\u679c <strong>possible_keys<\/strong> \u5217\u4e2d\u6709\u7d22\u5f15\uff0c\u4f46 <strong>key<\/strong> \u5217\u70ba <code>NULL<\/code>\uff0c\u9019\u8868\u793a\u67e5\u8a62\u672a\u80fd\u5229\u7528\u53ef\u7528\u7684\u7d22\u5f15\u3002\u9019\u53ef\u80fd\u662f\u56e0\u70ba\u67e5\u8a62\u689d\u4ef6\u4e0d\u7b26\u5408\u7d22\u5f15\u7684\u4f7f\u7528\u689d\u4ef6\uff0c\u6216\u8005\u7d22\u5f15\u7684\u9078\u64c7\u6027\u4e0d\u9ad8\u3002<\/p>\n<h3 id=\"3-%e9%a0%90%e4%bc%b0%e8%a1%8c%e6%95%b8%e4%b8%8d%e6%ba%96%e7%a2%ba-VkvcmAdrYl\">3. \u9810\u4f30\u884c\u6578\u4e0d\u6e96\u78ba<\/h3>\n<p>\u5982\u679c <strong>rows<\/strong> \u5217\u7684\u9810\u4f30\u884c\u6578\u8207\u5be6\u969b\u884c\u6578\u76f8\u5dee\u751a\u9060\uff0c\u9019\u53ef\u80fd\u6703\u5f71\u97ff\u67e5\u8a62\u7684\u6027\u80fd\u3002\u53ef\u4ee5\u901a\u904e\u66f4\u65b0\u7d71\u8a08\u4fe1\u606f\u4f86\u6539\u5584\u9019\u4e00\u9ede\uff0c\u4f7f\u7528 <code>ANALYZE TABLE<\/code> \u547d\u4ee4\u4f86\u66f4\u65b0\u8868\u7684\u7d71\u8a08\u4fe1\u606f\u3002<\/p>\n<h2 id=\"%e7%b5%90%e8%ab%96-VkvcmAdrYl\">\u7d50\u8ad6<\/h2>\n<p>\u638c\u63e1 <code>EXPLAIN<\/code> \u7684\u4f7f\u7528\u65b9\u6cd5\u548c\u7d50\u679c\u89e3\u8b80\uff0c\u5c0d\u65bc\u512a\u5316 MySQL \u67e5\u8a62\u6027\u80fd\u81f3\u95dc\u91cd\u8981\u3002\u901a\u904e\u5206\u6790\u57f7\u884c\u8a08\u5283\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u8b58\u5225\u6027\u80fd\u74f6\u9838\uff0c\u4e26\u63a1\u53d6\u76f8\u61c9\u7684\u63aa\u65bd\u4f86\u6539\u5584\u67e5\u8a62\u6548\u7387\u3002\u7121\u8ad6\u662f\u6dfb\u52a0\u7d22\u5f15\u3001\u8abf\u6574\u67e5\u8a62\u7d50\u69cb\uff0c\u9084\u662f\u66f4\u65b0\u7d71\u8a08\u4fe1\u606f\uff0c\u9019\u4e9b\u90fd\u662f\u63d0\u5347\u6578\u64da\u5eab\u6027\u80fd\u7684\u6709\u6548\u624b\u6bb5\u3002<\/p>\n<p>\u5982\u679c\u4f60\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 <a href=\"https:\/\/server.hk\">VPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u5e6b\u52a9\u4f60\u512a\u5316\u6578\u64da\u5eab\u6027\u80fd\uff0c\u63d0\u5347\u7db2\u7ad9\u901f\u5ea6\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3\u5982\u4f55\u4f7f\u7528 MySQL \u7684\u57f7\u884c\u8a08\u5283\uff08EXPLAIN\uff09\u4f86\u512a\u5316\u67e5\u8a62\u6027\u80fd\uff0c\u63d0\u5347\u6578\u64da\u5eab\u6548\u7387\u3002<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-170065","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/170065","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"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=170065"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/170065\/revisions"}],"predecessor-version":[{"id":170066,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/170065\/revisions\/170066"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=170065"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=170065"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=170065"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}