{"id":74367,"date":"2024-10-15T22:23:59","date_gmt":"2024-10-15T14:23:59","guid":{"rendered":"https:\/\/server.hk\/cnblog\/74367\/"},"modified":"2024-10-15T22:23:59","modified_gmt":"2024-10-15T14:23:59","slug":"mysql-explain%e8%aa%9e%e5%8f%a5%e7%9a%84%e4%bd%bf%e7%94%a8","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/74367\/","title":{"rendered":"MySQL EXPLAIN\u8a9e\u53e5\u7684\u4f7f\u7528"},"content":{"rendered":"<h1 id=\"mysql-explain%e8%aa%9e%e5%8f%a5%e7%9a%84%e4%bd%bf%e7%94%a8-EhcLclEtap\">MySQL EXPLAIN\u8a9e\u53e5\u7684\u4f7f\u7528<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\uff0c\u6027\u80fd\u512a\u5316\u662f\u81f3\u95dc\u91cd\u8981\u7684\uff0c\u800cMySQL\u7684EXPLAIN\u8a9e\u53e5\u662f\u4e00\u500b\u5f37\u5927\u7684\u5de5\u5177\uff0c\u53ef\u4ee5\u5e6b\u52a9\u958b\u767c\u8005\u548c\u6578\u64da\u5eab\u7ba1\u7406\u54e1\u5206\u6790\u67e5\u8a62\u7684\u57f7\u884c\u8a08\u5283\u3002\u900f\u904eEXPLAIN\u8a9e\u53e5\uff0c\u6211\u5011\u53ef\u4ee5\u4e86\u89e3MySQL\u662f\u5982\u4f55\u57f7\u884c\u7279\u5b9a\u67e5\u8a62\u7684\uff0c\u5f9e\u800c\u627e\u51fa\u6f5b\u5728\u7684\u6027\u80fd\u74f6\u9838\u3002<\/p>\n<h2 id=\"explain%e8%aa%9e%e5%8f%a5%e7%9a%84%e5%9f%ba%e6%9c%ac%e7%94%a8%e6%b3%95-EhcLclEtap\">EXPLAIN\u8a9e\u53e5\u7684\u57fa\u672c\u7528\u6cd5<\/h2>\n<p>EXPLAIN\u8a9e\u53e5\u7684\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>EXPLAIN SELECT * FROM table_name WHERE condition;<\/code><\/pre>\n<p>\u7576\u57f7\u884c\u9019\u500b\u8a9e\u53e5\u6642\uff0cMySQL\u6703\u8fd4\u56de\u4e00\u500b\u7d50\u679c\u96c6\uff0c\u986f\u793a\u67e5\u8a62\u7684\u57f7\u884c\u8a08\u5283\u3002\u9019\u4e9b\u7d50\u679c\u5305\u62ec\u4e86\u591a\u500b\u91cd\u8981\u7684\u6b04\u4f4d\uff0c\u4f8b\u5982\uff1a<\/p>\n<ul>\n<li><strong>id<\/strong>\uff1a\u67e5\u8a62\u7684\u8b58\u5225\u78bc\uff0c\u8868\u793a\u67e5\u8a62\u7684\u57f7\u884c\u9806\u5e8f\u3002<\/li>\n<li><strong>select_type<\/strong>\uff1a\u67e5\u8a62\u7684\u985e\u578b\uff0c\u4f8b\u5982\u7c21\u55ae\u67e5\u8a62\u3001\u806f\u63a5\u67e5\u8a62\u7b49\u3002<\/li>\n<li><strong>table<\/strong>\uff1a\u6b63\u5728\u8a2a\u554f\u7684\u8868\u540d\u3002<\/li>\n<li><strong>type<\/strong>\uff1a\u806f\u63a5\u985e\u578b\uff0c\u986f\u793a\u67e5\u8a62\u7684\u6548\u7387\uff0c\u5f9e\u6700\u512a\u7684\u201cconst\u201d\u5230\u6700\u5dee\u7684\u201cALL\u201d\u3002<\/li>\n<li><strong>possible_keys<\/strong>\uff1a\u53ef\u80fd\u4f7f\u7528\u7684\u7d22\u5f15\u3002<\/li>\n<li><strong>key<\/strong>\uff1a\u5be6\u969b\u4f7f\u7528\u7684\u7d22\u5f15\u3002<\/li>\n<li><strong>rows<\/strong>\uff1a\u9810\u4f30\u9700\u8981\u6383\u63cf\u7684\u884c\u6578\u3002<\/li>\n<li><strong>Extra<\/strong>\uff1a\u984d\u5916\u7684\u57f7\u884c\u4fe1\u606f\u3002<\/li>\n<\/ul>\n<h2 id=\"%e5%88%86%e6%9e%90explain%e7%9a%84%e7%b5%90%e6%9e%9c-EhcLclEtap\">\u5206\u6790EXPLAIN\u7684\u7d50\u679c<\/h2>\n<p>\u7406\u89e3EXPLAIN\u7684\u7d50\u679c\u5c0d\u65bc\u512a\u5316\u67e5\u8a62\u81f3\u95dc\u91cd\u8981\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684\u5206\u6790\u65b9\u6cd5\uff1a<\/p>\n<h3 id=\"1-%e8%81%af%e6%8e%a5%e9%a1%9e%e5%9e%8b-EhcLclEtap\">1. \u806f\u63a5\u985e\u578b<\/h3>\n<p>\u5728\u201ctype\u201d\u6b04\u4f4d\u4e2d\uff0c\u806f\u63a5\u985e\u578b\u7684\u503c\u53ef\u4ee5\u5e6b\u52a9\u6211\u5011\u5224\u65b7\u67e5\u8a62\u7684\u6548\u7387\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684\u985e\u578b\uff1a<\/p>\n<ul>\n<li><strong>ALL<\/strong>\uff1a\u5168\u8868\u6383\u63cf\uff0c\u6548\u7387\u6700\u4f4e\u3002<\/li>\n<li><strong>index<\/strong>\uff1a\u7d22\u5f15\u6383\u63cf\uff0c\u6548\u7387\u8f03\u9ad8\u3002<\/li>\n<li><strong>range<\/strong>\uff1a\u7bc4\u570d\u6383\u63cf\uff0c\u901a\u5e38\u662f\u57fa\u65bc\u7d22\u5f15\u7684\u67e5\u8a62\u3002<\/li>\n<li><strong>ref<\/strong>\uff1a\u975e\u552f\u4e00\u7d22\u5f15\u67e5\u8a62\uff0c\u6548\u7387\u8f03\u9ad8\u3002<\/li>\n<li><strong>const<\/strong>\uff1a\u5e38\u6578\u67e5\u8a62\uff0c\u6548\u7387\u6700\u9ad8\u3002<\/li>\n<\/ul>\n<h3 id=\"2-%e4%bd%bf%e7%94%a8%e7%b4%a2%e5%bc%95-EhcLclEtap\">2. \u4f7f\u7528\u7d22\u5f15<\/h3>\n<p>\u5728\u201cpossible_keys\u201d\u548c\u201ckey\u201d\u6b04\u4f4d\u4e2d\uff0c\u6211\u5011\u53ef\u4ee5\u770b\u5230\u67e5\u8a62\u53ef\u80fd\u4f7f\u7528\u7684\u7d22\u5f15\u548c\u5be6\u969b\u4f7f\u7528\u7684\u7d22\u5f15\u3002\u5982\u679c\u201cpossible_keys\u201d\u4e2d\u6709\u7d22\u5f15\u4f46\u201ckey\u201d\u70baNULL\uff0c\u9019\u53ef\u80fd\u610f\u5473\u8457\u67e5\u8a62\u672a\u80fd\u6709\u6548\u5229\u7528\u7d22\u5f15\uff0c\u5f9e\u800c\u5f71\u97ff\u6027\u80fd\u3002<\/p>\n<h3 id=\"3-%e9%a0%90%e4%bc%b0%e8%a1%8c%e6%95%b8-EhcLclEtap\">3. \u9810\u4f30\u884c\u6578<\/h3>\n<p>\u5728\u201crows\u201d\u6b04\u4f4d\u4e2d\uff0c\u9810\u4f30\u9700\u8981\u6383\u63cf\u7684\u884c\u6578\u53ef\u4ee5\u5e6b\u52a9\u6211\u5011\u4e86\u89e3\u67e5\u8a62\u7684\u7bc4\u570d\u3002\u5982\u679c\u9019\u500b\u6578\u5b57\u904e\u9ad8\uff0c\u53ef\u80fd\u9700\u8981\u8003\u616e\u512a\u5316\u67e5\u8a62\u6216\u6dfb\u52a0\u7d22\u5f15\u3002<\/p>\n<h2 id=\"%e5%84%aa%e5%8c%96%e6%9f%a5%e8%a9%a2%e7%9a%84%e5%bb%ba%e8%ad%b0-EhcLclEtap\">\u512a\u5316\u67e5\u8a62\u7684\u5efa\u8b70<\/h2>\n<p>\u6839\u64daEXPLAIN\u7684\u7d50\u679c\uff0c\u4ee5\u4e0b\u662f\u4e00\u4e9b\u512a\u5316\u67e5\u8a62\u7684\u5efa\u8b70\uff1a<\/p>\n<ul>\n<li>\u78ba\u4fdd\u4f7f\u7528\u9069\u7576\u7684\u7d22\u5f15\uff0c\u4ee5\u6e1b\u5c11\u5168\u8868\u6383\u63cf\u7684\u60c5\u6cc1\u3002<\/li>\n<li>\u907f\u514d\u5728WHERE\u5b50\u53e5\u4e2d\u4f7f\u7528\u4e0d\u5fc5\u8981\u7684\u51fd\u6578\uff0c\u9019\u53ef\u80fd\u6703\u5c0e\u81f4\u7d22\u5f15\u5931\u6548\u3002<\/li>\n<li>\u8003\u616e\u91cd\u69cb\u67e5\u8a62\uff0c\u5c07\u8907\u96dc\u7684\u67e5\u8a62\u62c6\u5206\u70ba\u591a\u500b\u7c21\u55ae\u67e5\u8a62\u3002<\/li>\n<li>\u5b9a\u671f\u5206\u6790\u548c\u66f4\u65b0\u7d71\u8a08\u4fe1\u606f\uff0c\u4ee5\u78ba\u4fdd\u67e5\u8a62\u512a\u5316\u5668\u80fd\u5920\u505a\u51fa\u6700\u4f73\u6c7a\u7b56\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-EhcLclEtap\">\u7e3d\u7d50<\/h2>\n<p>MySQL\u7684EXPLAIN\u8a9e\u53e5\u662f\u4e00\u500b\u5f37\u5927\u7684\u5de5\u5177\uff0c\u53ef\u4ee5\u5e6b\u52a9\u958b\u767c\u8005\u6df1\u5165\u4e86\u89e3\u67e5\u8a62\u7684\u57f7\u884c\u8a08\u5283\u3002\u900f\u904e\u5206\u6790EXPLAIN\u7684\u7d50\u679c\uff0c\u6211\u5011\u53ef\u4ee5\u627e\u51fa\u6027\u80fd\u74f6\u9838\u4e26\u9032\u884c\u76f8\u61c9\u7684\u512a\u5316\u3002\u7121\u8ad6\u662f\u5728\u958b\u767c\u968e\u6bb5\u9084\u662f\u904b\u884c\u968e\u6bb5\uff0c\u5b9a\u671f\u4f7f\u7528EXPLAIN\u4f86\u6aa2\u67e5\u67e5\u8a62\u6027\u80fd\u90fd\u662f\u4e00\u500b\u826f\u597d\u7684\u7fd2\u6163\u3002\u82e5\u60a8\u9700\u8981\u66f4\u9ad8\u6548\u7684\u6578\u64da\u5eab\u89e3\u6c7a\u65b9\u6848\uff0c\u8003\u616e\u4f7f\u7528<a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a>\u6216<a href=\"https:\/\/server.hk\">\u9999\u6e2f\u4f3a\u670d\u5668<\/a>\u4f86\u63d0\u5347\u60a8\u7684\u61c9\u7528\u6027\u80fd\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3MySQL EXPLAIN\u8a9e\u53e5\u7684\u4f7f\u7528\uff0c\u638c\u63e1\u67e5\u8a62\u6027\u80fd\u5206\u6790\uff0c\u512a\u5316\u6578\u64da\u5eab\u64cd\u4f5c\uff0c\u63d0\u9ad8\u67e5\u8a62\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-74367","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/74367","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=74367"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/74367\/revisions"}],"predecessor-version":[{"id":74368,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/74367\/revisions\/74368"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=74367"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=74367"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=74367"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}