{"id":609,"date":"2025-02-12T11:50:16","date_gmt":"2025-02-12T03:50:16","guid":{"rendered":"https:\/\/www.huangkeqin.cn\/?p=609"},"modified":"2025-04-03T16:02:40","modified_gmt":"2025-04-03T08:02:40","slug":"mysql%e7%b4%a2%e5%bc%95","status":"publish","type":"post","link":"https:\/\/www.huangkeqin.cn\/index.php\/2025\/02\/12\/mysql%e7%b4%a2%e5%bc%95\/","title":{"rendered":"MySQL\u7d22\u5f15"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\"><strong>\u95ee\u9898\uff1a\u5728MySQL\u4e2d\uff0c\u4e00\u4e2a\u5b57\u6bb5\u6ca1\u52a0\u7d22\u5f15\uff0c\u6bd4\u5982name,\u67e5\u8be2select * from table where name=&#8221;&#8221;\uff0c\u548c\u5b57\u6bb5\u52a0\u4e86name\u7d22\u5f15\uff0c\u67e5\u8be2select * from table where name=&#8221;&#8221;\uff0c\u4e24\u8005\u67e5\u8be2\u7684\u65b9\u5f0f\u548c\u6548\u7387\u662f\u4e00\u6837\u7684\u5417<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5728MySQL\u4e2d\uff0c\u5b57\u6bb5\u662f\u5426\u52a0\u7d22\u5f15\u5bf9\u67e5\u8be2\u65b9\u5f0f\u548c\u6548\u7387\u6709\u663e\u8457\u5f71\u54cd\u3002\u4ee5\u4e0b\u662f\u4e24\u8005\u7684\u5bf9\u6bd4\uff1a<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">1. <strong>\u67e5\u8be2\u65b9\u5f0f\u4e0d\u540c<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u65e0\u7d22\u5f15\u5b57\u6bb5<\/strong>\uff1a<br>\u5f53name\u5b57\u6bb5\u6ca1\u6709\u7d22\u5f15\u65f6\uff0c\u6267\u884cWHERE name=&#8221;&#8221;\u7684\u67e5\u8be2\u4f1a\u89e6\u53d1<strong>\u5168\u8868\u626b\u63cf<\/strong>\uff08Full Table Scan\uff09\u3002\u6570\u636e\u5e93\u9700\u8981\u9010\u884c\u68c0\u67e5\u6240\u6709\u8bb0\u5f55\u7684name\u5b57\u6bb5\uff0c\u76f4\u5230\u627e\u5230\u6240\u6709\u5339\u914d\u9879\u3002\u8fd9\u79cd\u65b9\u5f0f\u9700\u8981\u8bfb\u53d6\u6574\u4e2a\u8868\u7684\u6570\u636e\u9875\uff0c\u6548\u7387\u968f\u6570\u636e\u91cf\u589e\u957f\u800c\u663e\u8457\u4e0b\u964d\u3002<\/li>\n\n\n\n<li><strong>\u6709\u7d22\u5f15\u5b57\u6bb5<\/strong>\uff1a<br>\u5982\u679cname\u5b57\u6bb5\u6709\u7d22\u5f15\uff08\u5982B+Tree\u7d22\u5f15\uff09\uff0c\u6570\u636e\u5e93\u4f1a\u901a\u8fc7\u7d22\u5f15\u5feb\u901f\u5b9a\u4f4d\u5339\u914d\u7684\u8bb0\u5f55\u3002\u7d22\u5f15\u6309\u503c\u6392\u5e8f\uff0c\u67e5\u8be2\u65f6\u76f4\u63a5\u5b9a\u4f4d\u5230\u7b26\u5408\u6761\u4ef6\u7684\u7d22\u5f15\u6761\u76ee\uff0c\u518d\u901a\u8fc7\u6307\u9488\uff08\u5982\u4e3b\u952e\uff09\u56de\u8868\u83b7\u53d6\u5b8c\u6574\u6570\u636e\u3002\u8fd9\u4e00\u8fc7\u7a0b\u79f0\u4e3a<strong>\u7d22\u5f15\u67e5\u627e<\/strong>\uff0c\u907f\u514d\u4e86\u5168\u8868\u626b\u63cf\u3002<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">2. <strong>\u6548\u7387\u5dee\u5f02<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u5c0f\u6570\u636e\u91cf\u573a\u666f<\/strong>\uff1a<br>\u82e5\u8868\u4e2d\u6570\u636e\u91cf\u6781\u5c0f\uff08\u5982\u51e0\u767e\u884c\uff09\uff0c\u5168\u8868\u626b\u63cf\u53ef\u80fd\u6bd4\u7d22\u5f15\u67e5\u627e\u66f4\u5feb\u3002\u56e0\u4e3a\u4f7f\u7528\u7d22\u5f15\u9700\u8981\u989d\u5916\u7684I\/O\u8bfb\u53d6\u7d22\u5f15\u9875\u548c\u56de\u8868\u64cd\u4f5c\uff0c\u6b64\u65f6\u6027\u80fd\u5dee\u5f02\u53ef\u80fd\u4e0d\u660e\u663e\u3002<\/li>\n\n\n\n<li><strong>\u5927\u6570\u636e\u91cf\u573a\u666f<\/strong>\uff1a<br>\u5f53\u6570\u636e\u91cf\u8f83\u5927\u65f6\uff0c\u7d22\u5f15\u7684\u4f18\u52bf\u663e\u8457\u3002\u4f8b\u5982\uff0c\u5047\u8bbe\u8868\u6709100\u4e07\u884c\uff1a\n<ul class=\"wp-block-list\">\n<li><strong>\u65e0\u7d22\u5f15<\/strong>\uff1a\u9700\u626b\u63cf\u5168\u90e8100\u4e07\u884c\uff0c\u65f6\u95f4\u590d\u6742\u5ea6\u4e3aO(n)\u3002<\/li>\n\n\n\n<li><strong>\u6709\u7d22\u5f15<\/strong>\uff1a\u901a\u8fc7B+Tree\u7d22\u5f15\uff0c\u65f6\u95f4\u590d\u6742\u5ea6\u53ef\u964d\u81f3O(log n)\uff0c\u901a\u5e38\u53ea\u9700\u51e0\u6b21\u78c1\u76d8I\/O\u5373\u53ef\u5b9a\u4f4d\u6570\u636e\uff0c\u6027\u80fd\u63d0\u5347\u51e0\u4e2a\u6570\u91cf\u7ea7\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>\u8986\u76d6\u7d22\u5f15\u4f18\u5316<\/strong>\uff1a<br>\u5982\u679c\u67e5\u8be2\u4ec5\u9700\u7d22\u5f15\u5b57\u6bb5\uff08\u5982SELECT name FROM table WHERE name=&#8221;&#8221;\uff09\uff0c\u4e14\u7d22\u5f15\u5305\u542b\u6240\u6709\u9700\u8fd4\u56de\u7684\u5217\uff0c\u5219\u65e0\u9700\u56de\u8868\uff0c\u76f4\u63a5\u901a\u8fc7\u7d22\u5f15\u8fd4\u56de\u7ed3\u679c\uff08<strong>\u8986\u76d6\u7d22\u5f15<\/strong>\uff09\uff0c\u6548\u7387\u66f4\u9ad8\u3002<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">3. <strong>\u5176\u4ed6\u5f71\u54cd\u56e0\u7d20<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u7d22\u5f15\u9009\u62e9\u6027<\/strong>\uff1a<br>\u5982\u679cname\u5b57\u6bb5\u7684\u503c\u91cd\u590d\u7387\u9ad8\uff08\u598290%\u7684\u8bb0\u5f55name\u76f8\u540c\uff09\uff0c\u7d22\u5f15\u6548\u679c\u4f1a\u964d\u4f4e\u3002\u6b64\u65f6\u4f18\u5316\u5668\u53ef\u80fd\u9009\u62e9\u5168\u8868\u626b\u63cf\uff0c\u5373\u4f7f\u5b58\u5728\u7d22\u5f15\u3002<\/li>\n\n\n\n<li><strong>\u6570\u636e\u5206\u5e03<\/strong>\uff1a<br>\u82e5\u67e5\u8be2\u6761\u4ef6\u5339\u914d\u7684\u884c\u6570\u5360\u603b\u884c\u6570\u5f88\u5927\u6bd4\u4f8b\uff08\u5982\u8d85\u8fc720%\uff09\uff0c\u5168\u8868\u626b\u63cf\u53ef\u80fd\u66f4\u9ad8\u6548\u3002\u4f18\u5316\u5668\u4f1a\u6839\u636e\u7edf\u8ba1\u4fe1\u606f\u81ea\u52a8\u9009\u62e9\u6267\u884c\u8ba1\u5212\u3002<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">4. <strong>\u9a8c\u8bc1\u65b9\u5f0f<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u4f7f\u7528EXPLAIN\u547d\u4ee4\u67e5\u770b\u6267\u884c\u8ba1\u5212\uff1a sql EXPLAIN SELECT * FROM table WHERE name = &#8220;&#8221;;\n<ul class=\"wp-block-list\">\n<li><strong>\u65e0\u7d22\u5f15<\/strong>\uff1atype\u5217\u4e3aALL\uff08\u5168\u8868\u626b\u63cf\uff09\uff0crows\u63a5\u8fd1\u8868\u7684\u603b\u884c\u6570\u3002<\/li>\n\n\n\n<li><strong>\u6709\u7d22\u5f15<\/strong>\uff1atype\u53ef\u80fd\u4e3aref\u6216range\uff0crows\u663e\u8457\u51cf\u5c11\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">\u7ed3\u8bba<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u5b57\u6bb5\u662f\u5426\u52a0\u7d22\u5f15\u4f1a\u5bfc\u81f4<strong>\u5b8c\u5168\u4e0d\u540c\u7684\u67e5\u8be2\u65b9\u5f0f<\/strong>\uff0c\u5728\u5927\u591a\u6570\u573a\u666f\u4e0b\uff0c\u6709\u7d22\u5f15\u7684\u67e5\u8be2\u6548\u7387\u8fdc\u9ad8\u4e8e\u65e0\u7d22\u5f15\u3002\u4f46\u9700\u7ed3\u5408\u5b9e\u9645\u6570\u636e\u91cf\u3001\u7d22\u5f15\u9009\u62e9\u6027\u53ca\u67e5\u8be2\u6761\u4ef6\uff0c\u5408\u7406\u8bbe\u8ba1\u7d22\u5f15\uff0c\u907f\u514d\u8fc7\u5ea6\u7d22\u5f15\u5bfc\u81f4\u7684\u5199\u6027\u80fd\u4e0b\u964d\u548c\u7a7a\u95f4\u6d6a\u8d39\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u95ee\u9898\uff1a\u5728MySQL\u4e2d\uff0c\u4e00\u4e2a\u5b57\u6bb5\u6ca1\u52a0\u7d22\u5f15\uff0c\u6bd4\u5982name,\u67e5\u8be2select * from table where  [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-609","post","type-post","status-publish","format-standard","hentry","category-3"],"_links":{"self":[{"href":"https:\/\/www.huangkeqin.cn\/index.php\/wp-json\/wp\/v2\/posts\/609","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.huangkeqin.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.huangkeqin.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.huangkeqin.cn\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.huangkeqin.cn\/index.php\/wp-json\/wp\/v2\/comments?post=609"}],"version-history":[{"count":5,"href":"https:\/\/www.huangkeqin.cn\/index.php\/wp-json\/wp\/v2\/posts\/609\/revisions"}],"predecessor-version":[{"id":1070,"href":"https:\/\/www.huangkeqin.cn\/index.php\/wp-json\/wp\/v2\/posts\/609\/revisions\/1070"}],"wp:attachment":[{"href":"https:\/\/www.huangkeqin.cn\/index.php\/wp-json\/wp\/v2\/media?parent=609"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.huangkeqin.cn\/index.php\/wp-json\/wp\/v2\/categories?post=609"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.huangkeqin.cn\/index.php\/wp-json\/wp\/v2\/tags?post=609"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}