{"id":241757,"date":"2022-05-10T08:08:22","date_gmt":"2022-05-10T00:08:22","guid":{"rendered":"https:\/\/gulass.cn\/?p=241757"},"modified":"2022-05-04T19:09:25","modified_gmt":"2022-05-04T11:09:25","slug":"hash-index-in-mysql","status":"publish","type":"post","link":"https:\/\/gulass.cn\/hash-index-in-mysql.html","title":{"rendered":"\u54c8\u5e0c\u7d22\u5f15\u5728MySQL\u4e2d\u7684\u63a2\u7a76"},"content":{"rendered":"<table>\n<tbody>\n<tr>\n<td style=\"padding: 5px 12px; width: 25px; font-size: 22px; text-align: center; background: #E8E8E8; line-height: 30px; color: #999;\">\u5bfc\u8bfb<\/td>\n<td style=\"padding: 10px 10px 12px; line-height: 20px;\"><strong>\u4ec0\u4e48\u662f\u81ea\u9002\u5e94\u54c8\u5e0c\u7d22\u5f15(Adaptive Hash Index, AHI)\u5462\uff1f\u539f\u7406\u53c8\u662f\u600e\u6837\u7684\u5462\uff1f\u4e0b\u9762\u6211\u4eec\u5148\u4ece\u4e00\u4e2a\u4f8b\u5b50\u5f00\u59cb\u3002<\/strong><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/gulass.cn\/wp-content\/uploads\/2022\/05\/6-1-1024x683.jpg\" alt=\"\" width=\"1024\" height=\"683\" class=\"alignnone size-large wp-image-241758\" srcset=\"https:\/\/gulass.cn\/wp-content\/uploads\/2022\/05\/6-1-1024x683.jpg 1024w, https:\/\/gulass.cn\/wp-content\/uploads\/2022\/05\/6-1-300x200.jpg 300w, https:\/\/gulass.cn\/wp-content\/uploads\/2022\/05\/6-1-768x512.jpg 768w, https:\/\/gulass.cn\/wp-content\/uploads\/2022\/05\/6-1-1536x1024.jpg 1536w, https:\/\/gulass.cn\/wp-content\/uploads\/2022\/05\/6-1.jpg 1920w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><br \/>\n\u7ecf\u5e38\u6709\u670b\u53cb\u95ee\uff0cMySQL\u7684InnoDB\u5230\u5e95\u652f\u4e0d\u652f\u6301\u54c8\u5e0c\u7d22\u5f15\uff1f<\/p>\n<p>\u5bf9\u4e8eInnoDB\u7684\u54c8\u5e0c\u7d22\u5f15\uff0c\u786e\u5207\u7684\u5e94\u8be5\u8fd9\u4e48\u8bf4\uff1a<\/p>\n<p>(1)InnoDB\u7528\u6237\u65e0\u6cd5\u624b\u52a8\u521b\u5efa\u54c8\u5e0c\u7d22\u5f15\uff0c\u8fd9\u4e00\u5c42\u4e0a\u8bf4\uff0cInnoDB\u786e\u5b9e\u4e0d\u652f\u6301\u54c8\u5e0c\u7d22\u5f15\uff1b<\/p>\n<p>(2)InnoDB\u4f1a\u81ea\u8c03\u4f18(self-tuning)\uff0c\u5982\u679c\u5224\u5b9a\u5efa\u7acb\u81ea\u9002\u5e94\u54c8\u5e0c\u7d22\u5f15(Adaptive Hash Index, AHI)\uff0c\u80fd\u591f\u63d0\u5347\u67e5\u8be2\u6548\u7387\uff0cInnoDB\u81ea\u5df1\u4f1a\u5efa\u7acb\u76f8\u5173\u54c8\u5e0c\u7d22\u5f15\uff0c\u8fd9\u4e00\u5c42\u4e0a\u8bf4\uff0cInnoDB\u53c8\u662f\u652f\u6301\u54c8\u5e0c\u7d22\u5f15\u7684\uff1b<\/p>\n<p>\u90a3\u4ec0\u4e48\u662f\u81ea\u9002\u5e94\u54c8\u5e0c\u7d22\u5f15(Adaptive Hash Index, AHI)\u5462\uff1f\u539f\u7406\u53c8\u662f\u600e\u6837\u7684\u5462\uff1f\u54b1\u4eec\u5148\u4ece\u4e00\u4e2a\u4f8b\u5b50\u5f00\u59cb\u3002<\/p>\n<p>\u4e0d\u59a8\u8bbe\u6709InnoDB\u6570\u636e\u8868\uff1a<\/p>\n<pre>\r\nt(id PK, name KEY, sex, flag)\r\n<\/pre>\n<p>\u753b\u5916\u97f3\uff1aid\u662f\u4e3b\u952e\uff0cname\u5efa\u4e86\u666e\u901a\u7d22\u5f15\u3002 \u5047\u8bbe\u8868\u4e2d\u6709\u56db\u6761\u8bb0\u5f55\uff1a<\/p>\n<li>1, shenjian, m, A<\/li>\n<li>3, zhangsan, m, A<\/li>\n<li>5, lisi, m, A<\/li>\n<li>9, wangwu, f, B<\/li>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/gulass.cn\/wp-content\/uploads\/2022\/05\/6-2.png\" alt=\"\" width=\"365\" height=\"252\" class=\"alignnone size-full wp-image-241759\" srcset=\"https:\/\/gulass.cn\/wp-content\/uploads\/2022\/05\/6-2.png 365w, https:\/\/gulass.cn\/wp-content\/uploads\/2022\/05\/6-2-300x207.png 300w\" sizes=\"auto, (max-width: 365px) 100vw, 365px\" \/><br \/>\n\u5982\u4e0a\u56fe\uff0c\u901a\u8fc7\u524d\u5e8f\u77e5\u8bc6\uff0c\u5bb9\u6613\u77e5\u9053InnoDB\u5728\u4e3b\u952eid\u4e0a\u4f1a\u5efa\u7acb\u805a\u96c6\u7d22\u5f15(Clustered Index)\uff0c\u53f6\u5b50\u5b58\u50a8\u8bb0\u5f55\u672c\u8eab\uff0c\u5728name\u4e0a\u4f1a\u5efa\u7acb\u666e\u901a\u7d22\u5f15(Secondary Index)\uff0c\u53f6\u5b50\u5b58\u50a8\u4e3b\u952e\u503c\u3002<\/p>\n<p>\u53d1\u8d77\u4e3b\u952eid\u67e5\u8be2\u65f6\uff0c\u80fd\u591f\u901a\u8fc7\u805a\u96c6\u7d22\u5f15\uff0c\u76f4\u63a5\u5b9a\u4f4d\u5230\u884c\u8bb0\u5f55\u3002<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/gulass.cn\/wp-content\/uploads\/2022\/05\/6-3.png\" alt=\"\" width=\"425\" height=\"255\" class=\"alignnone size-full wp-image-241760\" srcset=\"https:\/\/gulass.cn\/wp-content\/uploads\/2022\/05\/6-3.png 425w, https:\/\/gulass.cn\/wp-content\/uploads\/2022\/05\/6-3-300x180.png 300w\" sizes=\"auto, (max-width: 425px) 100vw, 425px\" \/><\/p>\n<pre>\r\nselect * from t where name='ls';\r\n<\/pre>\n<p>\u53d1\u8d77\u666e\u901a\u7d22\u5f15\u67e5\u8be2\u65f6\uff1a<\/p>\n<p>(1)\u4f1a\u5148\u4ece\u666e\u901a\u7d22\u5f15\u67e5\u8be2\u51fa\u4e3b\u952e(\u4e0a\u56fe\u53f3\u8fb9)\uff1b<\/p>\n<p>(2)\u518d\u7531\u4e3b\u952e\uff0c\u4ece\u805a\u96c6\u7d22\u5f15\u4e0a\u4e8c\u6b21\u904d\u5386\u5b9a\u4f4d\u5230\u8bb0\u5f55(\u4e0a\u56fe\u5de6\u8fb9)\u3002<\/p>\n<p>\u4e0d\u7ba1\u805a\u96c6\u7d22\u5f15\u8fd8\u662f\u666e\u901a\u7d22\u5f15\uff0c\u8bb0\u5f55\u5b9a\u4f4d\u7684\u5bfb\u8def\u8def\u5f84(Search Path)\u90fd\u5f88\u957f\u3002<\/p>\n<p>\u5728MySQL\u8fd0\u884c\u7684\u8fc7\u7a0b\u4e2d\uff0c\u5982\u679cInnoDB\u53d1\u73b0\uff0c\u6709\u5f88\u591aSQL\u5b58\u5728\u8fd9\u7c7b\u5f88\u957f\u7684\u5bfb\u8def\uff0c\u5e76\u4e14\u6709\u5f88\u591aSQL\u4f1a\u547d\u4e2d\u76f8\u540c\u7684\u9875\u9762(page)\uff0cInnoDB\u4f1a\u5728\u81ea\u5df1\u7684\u5185\u5b58\u7f13\u51b2\u533a(Buffer)\u91cc\uff0c\u5f00\u8f9f\u4e00\u5757\u533a\u57df\uff0c\u5efa\u7acb\u81ea\u9002\u5e94\u54c8\u5e0c\u6240\u6709AHI\uff0c\u4ee5\u52a0\u901f\u67e5\u8be2\u3002<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/gulass.cn\/wp-content\/uploads\/2022\/05\/6-4.png\" alt=\"\" width=\"427\" height=\"347\" class=\"alignnone size-full wp-image-241761\" srcset=\"https:\/\/gulass.cn\/wp-content\/uploads\/2022\/05\/6-4.png 427w, https:\/\/gulass.cn\/wp-content\/uploads\/2022\/05\/6-4-300x244.png 300w\" sizes=\"auto, (max-width: 427px) 100vw, 427px\" \/><\/p>\n<p>\u4ece\u8fd9\u4e2a\u5c42\u9762\u4e0a\u6765\u8bf4\uff0cInnoDB\u7684\u81ea\u4f7f\u7528\u54c8\u5e0c\u7d22\u5f15\uff0c\u66f4\u50cf\u201c\u7d22\u5f15\u7684\u7d22\u5f15\u201d\uff0c\u6bd5\u7adf\u5176\u76ee\u7684\u662f\u4e3a\u4e86\u52a0\u901f\u7d22\u5f15\u5bfb\u8def\u3002<\/p>\n<p>\u65e2\u7136\u662f\u54c8\u5e0c\uff0ckey\u662f\u4ec0\u4e48\uff0cvalue\u662f\u4ec0\u4e48\uff1f<\/p>\n<p>key\u662f\u7d22\u5f15\u952e\u503c(\u6216\u8005\u952e\u503c\u524d\u7f00)\u3002<\/p>\n<p>value\u662f\u7d22\u5f15\u8bb0\u5f55\u9875\u9762\u4f4d\u7f6e\u3002<\/p>\n<p>\u4e3a\u5565\u53eb\u201c\u81ea\u9002\u5e94(adaptive)\u201d\u54c8\u5e0c\u7d22\u5f15\uff1f<\/p>\n<p>\u7cfb\u7edf\u81ea\u5df1\u5224\u65ad\u201c\u5e94\u8be5\u53ef\u4ee5\u52a0\u901f\u67e5\u8be2\u201d\u800c\u5efa\u7acb\u7684\uff0c\u4e0d\u9700\u8981\u7528\u6237\u624b\u52a8\u5efa\u7acb\uff0c\u6545\u79f0\u201c\u81ea\u9002\u5e94\u201d\u3002<\/p>\n<p>\u7cfb\u7edf\u4f1a\u4e0d\u4f1a\u5224\u65ad\u5931\u8bef\uff0c\u662f\u4e0d\u662f\u4e00\u5b9a\u80fd\u52a0\u901f\uff1f<\/p>\n<p>\u4e0d\u662f\u4e00\u5b9a\u80fd\u52a0\u901f\uff0c\u6709\u65f6\u5019\u4f1a\u8bef\u5224\u3002 \u5f53\u4e1a\u52a1\u573a\u666f\u4e3a\u4e0b\u9762\u51e0\u79cd\u60c5\u51b5\u65f6\uff1a<\/p>\n<p>(1)\u5f88\u591a\u5355\u884c\u8bb0\u5f55\u67e5\u8be2(\u4f8b\u5982passport\uff0c\u7528\u6237\u4e2d\u5fc3\u7b49\u4e1a\u52a1);<\/p>\n<p>(2)\u7d22\u5f15\u8303\u56f4\u67e5\u8be2(\u6b64\u65f6AHI\u53ef\u4ee5\u5feb\u901f\u5b9a\u4f4d\u9996\u884c\u8bb0\u5f55);<\/p>\n<p>(3)\u6240\u6709\u8bb0\u5f55\u5185\u5b58\u80fd\u653e\u5f97\u4e0b;<\/p>\n<p>AHI\u5f80\u5f80\u662f\u6709\u6548\u7684\u3002<\/p>\n<p>\u753b\u5916\u97f3\uff1a\u4efb\u4f55\u8131\u79bb\u4e1a\u52a1\u7684\u6280\u672f\u65b9\u6848\uff0c\u90fd\u662f\u800d\u6d41\u6c13\u3002<\/p>\n<p>\u5f53\u4e1a\u52a1\u6709\u5927\u91cflike\u6216\u8005join\uff0cAHI\u7684\u7ef4\u62a4\u53cd\u800c\u53ef\u80fd\u6210\u4e3a\u8d1f\u62c5\uff0c\u964d\u4f4e\u7cfb\u7edf\u6548\u7387\uff0c\u6b64\u65f6\u53ef\u4ee5\u624b\u52a8\u5173\u95edAHI\u529f\u80fd\u3002<\/p>\n<p>\u4e00\u4e2a\u5c0f\u77e5\u8bc6\u70b9\uff0c\u5e0c\u671b\u5bf9\u5927\u5bb6\u6709\u5e2e\u52a9\u3002<\/p>\n<p>\u77e5\u5176\u7136\uff0c\u77e5\u5176\u6240\u4ee5\u7136\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u7ecf\u5e38\u6709\u670b\u53cb\u95ee\uff0cMySQL\u7684InnoDB\u5230\u5e95\u652f\u4e0d\u652f\u6301\u54c8\u5e0c\u7d22\u5f15\uff1f \u5bf9\u4e8eInnoDB\u7684\u54c8\u5e0c\u7d22\u5f15\uff0c\u786e\u5207\u7684\u5e94\u8be5\u8fd9\u4e48\u8bf4\uff1a  [&hellip;]<\/p>\n","protected":false},"author":1898,"featured_media":241762,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[55],"tags":[846],"class_list":["post-241757","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-thread","tag-846"],"acf":[],"_links":{"self":[{"href":"https:\/\/gulass.cn\/wp-json\/wp\/v2\/posts\/241757","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/gulass.cn\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/gulass.cn\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/gulass.cn\/wp-json\/wp\/v2\/users\/1898"}],"replies":[{"embeddable":true,"href":"https:\/\/gulass.cn\/wp-json\/wp\/v2\/comments?post=241757"}],"version-history":[{"count":1,"href":"https:\/\/gulass.cn\/wp-json\/wp\/v2\/posts\/241757\/revisions"}],"predecessor-version":[{"id":241763,"href":"https:\/\/gulass.cn\/wp-json\/wp\/v2\/posts\/241757\/revisions\/241763"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/gulass.cn\/wp-json\/wp\/v2\/media\/241762"}],"wp:attachment":[{"href":"https:\/\/gulass.cn\/wp-json\/wp\/v2\/media?parent=241757"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/gulass.cn\/wp-json\/wp\/v2\/categories?post=241757"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/gulass.cn\/wp-json\/wp\/v2\/tags?post=241757"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}