{"id":200847,"date":"2025-05-06T13:09:11","date_gmt":"2025-05-06T05:09:11","guid":{"rendered":"https:\/\/server.hk\/cnblog\/200847\/"},"modified":"2025-05-06T13:09:11","modified_gmt":"2025-05-06T05:09:11","slug":"mysql-mvcc%e4%b8%8bupdate%e5%90%8eselect%e4%b8%ba%e4%bb%80%e4%b9%88%e8%bf%98%e8%83%bd%e8%af%bb%e5%88%b0%e6%95%b0%e6%8d%ae%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/200847\/","title":{"rendered":"MySQL MVCC\u4e0bupdate\u540eselect\u4e3a\u4ec0\u4e48\u8fd8\u80fd\u8bfb\u5230\u6570\u636e\uff1f"},"content":{"rendered":"<p><b><\/b> <\/p>\n<h1>MySQL MVCC\u4e0bupdate\u540eselect\u4e3a\u4ec0\u4e48\u8fd8\u80fd\u8bfb\u5230\u6570\u636e\uff1f<\/h1>\n<p>\u600e\u4e48\u5165\u95e8\u6570\u636e\u5e93\u7f16\u7a0b\uff1f\u9700\u8981\u5b66\u4e60\u54ea\u4e9b\u77e5\u8bc6\u70b9\uff1f\u8fd9\u662f\u65b0\u624b\u4eec\u521a\u63a5\u89e6\u7f16\u7a0b\u65f6\u5e38\u89c1\u7684\u95ee\u9898\uff1b\u4e0b\u9762\u4e3b\u673a\u5b9d\u8d1d\u5c31\u6765\u7ed9\u5927\u5bb6\u6574\u7406\u5206\u4eab\u4e00\u4e9b\u77e5\u8bc6\u70b9\uff0c\u5e0c\u671b\u80fd\u591f\u7ed9\u521d\u5b66\u8005\u4e00\u4e9b\u5e2e\u52a9\u3002\u672c\u7bc7\u6587\u7ae0\u5c31\u6765\u4ecb\u7ecd\u300aMySQL MVCC\u4e0bupdate\u540eselect\u4e3a\u4ec0\u4e48\u8fd8\u80fd\u8bfb\u5230\u6570\u636e\uff1f\u300b\uff0c\u6d89\u53ca\u5230\uff0c\u6709\u9700\u8981\u7684\u53ef\u4ee5\u6536\u85cf\u4e00\u4e0b<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.17golang.com\/uploads\/20241117\/173180902667394f02d8934.jpg\" class=\"aligncenter\"><\/p>\n<p><strong>MySQL\u4e2dMVVC\u673a\u5236\u4e0bupdate\u4e4b\u540eselect\u5feb\u7167\u8bfb\u73b0\u8c61<\/strong><\/p>\n<p>\u5728MySQL\u4e2d\uff0c\u4e8b\u52a1\u9694\u79bb\u7ea7\u522b\u4e3aREAD COMMITTED\u65f6\uff0c\u4f7f\u7528\u591a\u7248\u672c\u5e76\u53d1\u63a7\u5236\uff08MVVC\uff09\u673a\u5236\u6765\u5b9e\u73b0\u5feb\u7167\u8bfb\u3002<\/p>\n<p>MVVC\u673a\u5236\u901a\u8fc7\u7ef4\u62a4\u6bcf\u4e2a\u67e5\u8be2\u7684\u53ef\u89c1\u5feb\u7167\u70b9\uff08SCN\uff09\uff0c\u5e76\u5229\u7528\u7cfb\u7edf\u7248\u672c\u8868\uff08redo log\uff09\u6765\u5b9e\u73b0\uff0c\u4fdd\u8bc1\u6bcf\u4e2a\u4e8b\u52a1\u90fd\u53ef\u4ee5\u8bbf\u95ee\u67e5\u8be2\u5f00\u59cb\u65f6\u6570\u636e\u5e93\u7684\u4e00\u81f4\u6027\u89c6\u56fe\u3002<\/p>\n<p>\u5f53\u4e8b\u52a1A\u6267\u884cupdate\u8bed\u53e5\u4fee\u6539\u4e00\u884c\u6570\u636e\u540e\uff0c\u8be5\u884c\u6570\u636e\u7684SCN\u503c\u4f1a\u589e\u52a0\u3002\u5982\u679c\u968f\u540e\u53e6\u4e00\u4e2a\u4e8b\u52a1B\u6267\u884cselect\u8bed\u53e5\u67e5\u8be2\u8be5\u884c\u6570\u636e\uff0c\u5219\u4f1a\u4f7f\u7528\u8be5\u884c\u6570\u636e\u7684SCN\u503c\u4e0e\u5176\u53ef\u89c1\u5feb\u7167\u70b9\u8fdb\u884c\u6bd4\u8f83\uff0c\u4ee5\u786e\u5b9a\u662f\u5426\u53ef\u89c1\u3002<\/p>\n<p>\u6839\u636eMVVC\u673a\u5236\u7684\u5339\u914d\u89c4\u5219\uff0c\u5f53\u884c\u6570\u636e\u7684SCN\u503c\u4ecb\u4e8e\u4e8b\u52a1B\u7684SCN\u503c\uff08m_low_limit_id\uff09\u548c\u4e0a\u9650SCN\u503c\uff08m_up_limit_id\uff09\u4e4b\u95f4\u7684\uff0c\u5219\u8be5\u884c\u6570\u636e\u5bf9\u4e8e\u4e8b\u52a1B\u662f\u4e0d\u53ef\u89c1\u7684\u3002<\/p>\n<p>\u7136\u800c\uff0c\u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u6ee1\u8db3\u7b2c\u4e00\u6761\u5339\u914d\u89c4\u5219\u65f6\uff0cupdate\u540eselect\u4ecd\u7136\u80fd\u591f\u67e5\u8be2\u5230\u6570\u636e\u3002\u8be5\u89c4\u5219\u5982\u4e0b\uff1a<\/p>\n<ul>\n<li>\u5982\u679c\u884c\u6570\u636e\u7684SCN\u503c\u5927\u4e8e\u7b49\u4e8e\u4e8b\u52a1B\u7684m_up_limit_id\uff0c\u5e76\u4e14\u884c\u6570\u636e\u7684update\u8bed\u53e5\u5c5e\u4e8e\u4e8b\u52a1B\u81ea\u8eab\uff0c\u5219\u8be5\u884c\u6570\u636e\u5bf9\u4e8e\u4e8b\u52a1B\u662f\u53ef\u89c1\u7684\u3002<\/li>\n<\/ul>\n<p>\u56e0\u6b64\uff0c\u5728\u95ee\u9898\u4e2d\uff0c\u4e8b\u52a1A\u6267\u884cupdate\u8bed\u53e5\u540e\uff0cid=5\u7684\u6570\u636e\u7684SCN\u503c\u589e\u52a0\u4e86\u3002\u7b2c\u4e8c\u6b21 select \u65f6\uff0c\u867d\u7136\u8be5\u6570\u636e\u4ecd\u7136\u4ecb\u4e8e\u4e8b\u52a1A\u548cB\u7684SCN\u503c\u4e4b\u95f4\uff0c\u4f46\u7531\u4e8e\u8be5\u6570\u636e\u662f\u7531\u4e8b\u52a1A\u81ea\u8eab\u66f4\u65b0\u7684\uff08\u5c5e\u4e8e\u4e8b\u52a1A\uff09\uff0c\u56e0\u6b64\u6ee1\u8db3\u4e86\u7b2c\u4e00\u6761\u5339\u914d\u89c4\u5219\uff0c\u6240\u4ee5\u4e8b\u52a1B\u80fd\u591f\u67e5\u770b\u5230\u8be5\u6570\u636e\u3002<\/p>\n<p>\u4eca\u5929\u5e26\u5927\u5bb6\u4e86\u89e3\u4e86\u7684\u76f8\u5173\u77e5\u8bc6\uff0c\u5e0c\u671b\u5bf9\u4f60\u6709\u6240\u5e2e\u52a9\uff1b\u5173\u4e8e\u6570\u636e\u5e93\u7684\u6280\u672f\u77e5\u8bc6\u6211\u4eec\u4f1a\u4e00\u70b9\u70b9\u6df1\u5165\u4ecb\u7ecd\uff0c\u6b22\u8fce\u5927\u5bb6\u5173\u6ce8\u4e3b\u673a\u5b9d\u8d1d\u516c\u4f17\u53f7\uff0c\u4e00\u8d77\u5b66\u4e60\u7f16\u7a0b~<\/p>\n<dl>\n<dt>\n <\/dt>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"<p>MySQL MVCC\u4e0bupdat&#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-200847","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200847","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=200847"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200847\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=200847"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=200847"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=200847"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}