{"id":1056,"date":"2014-10-20T22:53:39","date_gmt":"2014-10-20T14:53:39","guid":{"rendered":"http:\/\/coderbee.net\/?p=1056"},"modified":"2014-11-27T22:37:07","modified_gmt":"2014-11-27T14:37:07","slug":"mysql-%e4%ba%8b%e5%8a%a1%e9%9a%94%e7%a6%bb%e7%ba%a7%e5%88%ab%e4%b8%8emvcc","status":"publish","type":"post","link":"https:\/\/coderbee.net\/index.php\/db\/20141020\/1056","title":{"rendered":"MySQL \u4e8b\u52a1\u9694\u79bb\u7ea7\u522b\u4e0eMVCC"},"content":{"rendered":"<h2>\u4e00\u3001\u9694\u79bb\u7ea7\u522b<\/h2>\n<p>\u53c2\u8003\u4e86\u7ef4\u57fa\u767e\u79d1\uff1a<a href=\"http:\/\/zh.wikipedia.org\/zh\/%E4%BA%8B%E5%8B%99%E9%9A%94%E9%9B%A2\">\u4e8b\u52d9\u9694\u96e2<\/a><\/p>\n<p>\u9694\u79bb\u7ea7\u522b\u89c4\u5b9a\u4e86\u4e00\u4e2a\u4e8b\u52a1\u4e2d\u6240\u505a\u7684\u4fee\u6539\uff0c\u54ea\u4e9b\u5728\u4e8b\u52a1\u5185\u548c\u4e8b\u52a1\u95f4\u662f\u53ef\u89c1\u7684\uff0c\u54ea\u4e9b\u662f\u4e0d\u53ef\u89c1\u7684\u3002<\/p>\n<p>\u4e0b\u9762\u5bf9\u9694\u79bb\u7ea7\u522b\u7684\u8bf4\u660e\u90fd\u662f\u57fa\u4e8e<em>\u9501\u673a\u5236\u5e76\u53d1\u63a7\u5236<\/em>\u7684\u6570\u636e\u5e93\u7ba1\u7406\u7cfb\u7edf\u800c\u8a00\u3002<\/p>\n<h3>1. \u53ef\u5e8f\u5217\u5316\uff08Serializable\uff09<\/h3>\n<p>\u5b9e\u73b0\u53ef\u5e8f\u5217\u5316\u8981\u6c42\u5728\u9009\u5b9a\u5bf9\u8c61\u4e0a\u7684\u8bfb\u9501\u548c\u5199\u9501\u4fdd\u6301\u76f4\u5230\u4e8b\u52a1\u7ed3\u675f\u540e\u624d\u80fd\u91ca\u653e\u3002\u5728 <code>SELECT<\/code> \u7684\u67e5\u8be2\u4e2d\u4f7f\u7528\u4e00\u4e2a <code>WHERE<\/code> \u5b50\u53e5\u6765\u63cf\u8ff0\u4e00\u4e2a\u8303\u56f4\u65f6\u5e94\u8be5\u83b7\u5f97\u4e00\u4e2a\u201c\u8303\u56f4\u9501(range-locks)\u201d\u3002\u8fd9\u79cd\u673a\u5236\u53ef\u4ee5\u907f\u514d\u201c\u5e7b\u5f71\u8bfb(phantom reads)\u201d\u73b0\u8c61\u3002<\/p>\n<p>\u53ef\u5e8f\u5217\u5316\u662f\u6700\u9ad8\u7ea7\u522b\u7684\u9694\u79bb\u3002<\/p>\n<h3>2. \u53ef\u91cd\u590d\u8bfb\uff08Repeatable read\uff09<\/h3>\n<p>\u8be5\u7ea7\u522b\u4fdd\u8bc1\u4e86\u540c\u4e00\u4e2a\u4e8b\u52a1\u4e2d\u591a\u6b21\u8bfb\u53d6\u540c\u6837\u7684\u8bb0\u5f55\u7684\u7ed3\u679c\u662f\u4e00\u81f4\u7684\u3002<\/p>\n<p>\u5bf9\u9009\u5b9a\u5bf9\u8c61\u7684\u8bfb\u9501(read locks)\u548c\u5199\u9501(write locks)\u4e00\u76f4\u4fdd\u6301\u5230\u4e8b\u52a1\u7ed3\u675f\uff0c\u4f46\u4e0d\u8981\u6c42\u201c\u8303\u56f4\u9501(range-locks)\u201d\uff0c\u56e0\u6b64\u53ef\u80fd\u4f1a\u53d1\u751f\u201c\u5e7b\u5f71\u8bfb(phantom reads)\u201d\u3002<\/p>\n<p><strong>\u5e7b\u5f71\u8bfb<\/strong>\uff1a\u662f\u56e0\u4e3a\u6ca1\u6709\u4fdd\u6301\u8303\u56f4\u9501\uff0c\u8be5\u4e8b\u52a1\u6267\u884c\u4e86\u4e00\u4e2a where \u5b50\u53e5\u7684\u8303\u56f4\u67e5\u8be2\u540e\uff0c\u5176\u4ed6\u4e8b\u52a1\u53ef\u80fd\u65b0\u589e\u4e86\u4e00\u6761\u5904\u4e8e\u8be5\u4e8b\u52a1 where \u67e5\u8be2\u8303\u56f4\u5185\u7684\u8bb0\u5f55\uff0c\u90a3\u4e48\u8be5\u4e8b\u52a1\u518d\u6b21\u6267\u884c\u8303\u56f4\u67e5\u8be2\u65f6\u5c31\u4f1a\u770b\u5230\u8fd9\u4e9b\u65b0\u589e\u7684\u8bb0\u5f55\u884c\uff08\u5e7b\u884c\uff0cPhantom row\uff09\u3002<\/p>\n<p>\u53ef\u91cd\u590d\u8bfb\u662f MySQL \u7684\u9ed8\u8ba4\u4e8b\u52a1\u9694\u79bb\u7ea7\u522b\u3002<\/p>\n<h3>3.\u63d0\u4ea4\u8bfb\uff08Read committed\uff09<\/h3>\n<p>\u8be5\u7ea7\u522b\u4e5f\u53eb\u4e0d\u53ef\u91cd\u590d\u8bfb\uff08nonrepeatable read\uff09\u3002<\/p>\n<p>DBMS\u9700\u8981\u5bf9\u9009\u5b9a\u5bf9\u8c61\u7684\u5199\u9501(write locks)\u4e00\u76f4\u4fdd\u6301\u5230\u4e8b\u52a1\u7ed3\u675f\uff0c\u4f46\u662f\u8bfb\u9501(read locks)\u5728SELECT\u64cd\u4f5c\u5b8c\u6210\u540e\u9a6c\u4e0a\u91ca\u653e\uff08\u56e0\u6b64\u201c\u4e0d\u53ef\u91cd\u590d\u8bfb\u201d\u73b0\u8c61\u53ef\u80fd\u4f1a\u53d1\u751f\uff0c\u89c1\u4e0b\u9762\u63cf\u8ff0\uff09\u3002\u548c\u524d\u4e00\u79cd\u9694\u79bb\u7ea7\u522b\u4e00\u6837\uff0c\u4e5f\u4e0d\u8981\u6c42\u201c\u8303\u56f4\u9501(range-locks)\u201d\u3002<\/p>\n<p>\u4e0d\u53ef\u91cd\u590d\u8bfb\u662f\u56e0\u4e3a\uff0c\u4e8b\u52a1\u53ea\u7ef4\u6301\u4e86\u9009\u5b9a\u5bf9\u8c61\u7684\u5199\u9501\uff0c\u5982\u679c\u4e00\u4e9b\u9009\u5b9a\u5bf9\u8c61\u53ea\u6d89\u53ca\u8bfb\u9501\uff0c\u90a3\u4e48\u5728\u8bfb\u9501\u91ca\u653e\u4e4b\u540e\uff0c\u5176\u5b83\u4e8b\u52a1\u53ef\u4ee5\u5bf9\u8fd9\u4e9b\u5bf9\u8c61\u8fdb\u884c\u4fee\u6539\uff0c\u8be5\u4e8b\u52a1\u518d\u6b21\u8bfb\u53d6\u65f6\u5c31\u4e0d\u4e00\u81f4\u4e86\u3002<\/p>\n<p>\u5927\u591a\u6570\u6570\u636e\u5e93\u7684\u9ed8\u8ba4\u4e8b\u52a1\u9694\u79bb\u7ea7\u522b\u90fd\u662f\u8fd9\u4e2a\u3002<\/p>\n<h3>4. \u672a\u63d0\u4ea4\u8bfb\uff08Read uncommitted\uff09<\/h3>\n<p>\u4e5f\u79f0\u4e3a\u810f\u8bfb\uff08dirty read\uff09\u3002<\/p>\n<p>\u4e00\u4e2a\u4e8b\u52a1\u53ef\u4ee5\u8bfb\u53d6\u5230\u5176\u5b83\u4e8b\u52a1\u672a\u63d0\u4ea4\u7684\u66f4\u6539\u3002<\/p>\n<p><strong>\u4e0d\u53ef\u91cd\u590d\u8bfb\u7684\u91cd\u70b9\u662f\u4fee\u6539<\/strong>\uff1a\u540c\u6837\u7684\u6761\u4ef6\uff0c\u8bfb\u53d6\u8fc7\u7684\u6570\u636e\uff0c\u518d\u6b21\u8bfb\u53d6\u51fa\u6765\u53d1\u73b0\u503c\u4e0d\u4e00\u6837\u4e86\u3002<\/p>\n<p><strong>\u5e7b\u8bfb\u7684\u91cd\u70b9\u5728\u4e8e\u65b0\u589e\u6216\u8005\u5220\u9664<\/strong>\uff1a\u540c\u6837\u7684\u6761\u4ef6\uff0c\u7b2c 1 \u6b21\u548c\u7b2c 2 \u6b21\u8bfb\u51fa\u6765\u7684\u8bb0\u5f55\u6570\u4e0d\u4e00\u6837\u3002<\/p>\n<p><!--more--><\/p>\n<h2>\u4e8c\u3001\u591a\u7248\u672c\u5e76\u53d1\u63a7\u5236<\/h2>\n<p>\u591a\u7248\u672c\u5e76\u53d1\u63a7\u5236\uff08MVCC\uff09\u7684\u5b9e\u73b0\u662f\u901a\u8fc7\u4fdd\u5b58\u6570\u636e\u5728\u67d0\u4e2a\u65f6\u95f4\u70b9\u7684\u5feb\u7167\u6765\u5b9e\u73b0\u7684\u3002\u6839\u636e\u4e8b\u52a1\u5f00\u59cb\u7684\u65f6\u95f4\u4e0d\u540c\uff0c\u6bcf\u4e2a\u4e8b\u52a1\u5bf9\u540c\u4e00\u5f20\u8868\uff0c\u540c\u4e00\u65f6\u523b\u770b\u5230\u7684\u6570\u636e\u53ef\u80fd\u662f\u4e0d\u4e00\u6837\u7684\u3002<\/p>\n<p>InnoDB \u7684 MVCC \u662f\u901a\u8fc7\u5728\u6bcf\u884c\u8bb0\u5f55\u540e\u9762\u4fdd\u5b58\u4e24\u4e2a\u9690\u85cf\u7684\u5217\u6765\u5b9e\u73b0\u7684\uff1a\u4e00\u4e2a\u5217\u4fdd\u5b58\u4e86\u884c\u7684\u521b\u5efa\u65f6\u95f4\uff0c\u4e00\u4e2a\u4fdd\u5b58\u884c\u7684\u8fc7\u671f\u65f6\u95f4\uff08\u6216\u5220\u9664\u65f6\u95f4\uff09\u3002\u5b58\u50a8\u7684\u5b9e\u9645\u503c\u662f\u7cfb\u7edf\u7248\u672c\u53f7\uff08system version number\uff09\u3002<\/p>\n<p>\u6bcf\u5f00\u59cb\u4e00\u4e2a\u65b0\u7684\u4e8b\u52a1\uff0c\u7cfb\u7edf\u7248\u672c\u53f7\u90fd\u4f1a\u9012\u589e\u3002\u4e8b\u52a1\u5f00\u59cb\u65f6\u523b\u7684\u7cfb\u7edf\u7248\u672c\u53f7\u4f5c\u4e3a\u4e8b\u52a1\u7684\u7248\u672c\u53f7\uff0c\u7528\u6765\u548c\u67e5\u8be2\u5230\u7684\u6bcf\u884c\u8bb0\u5f55\u7684\u7248\u672c\u53f7\u8fdb\u884c\u6bd4\u8f83\u3002<\/p>\n<p>\u5728 REPEATABLE READ \u9694\u79bb\u7ea7\u522b\u4e0b\uff0cMVCC \u7684\u5177\u4f53\u64cd\u4f5c\uff1a<\/p>\n<ul>\n<li>\n<p>select\uff1aInnoDB \u6839\u636e\u4ee5\u4e0b\u4e24\u4e2a\u6761\u4ef6\u68c0\u67e5\u6bcf\u884c\u8bb0\u5f55\uff1a<\/p>\n<blockquote>\n<p>a\u3001 InnoDB \u53ea\u67e5\u627e\u7248\u672c\u65e9\u4e8e\u5f53\u524d\u4e8b\u52a1\u7248\u672c\u7684\u6570\u636e\u884c\uff08\u4e5f\u5373\u662f\u884c\u7684\u7248\u672c\u53f7\u5c0f\u4e8e\u7b49\u4e8e\u4e8b\u52a1\u7684\u7cfb\u7edf\u7248\u672c\u53f7\uff09\uff0c\u8fd9\u6837\u53ef\u4ee5\u786e\u4fdd\u4e8b\u52a1\u8bfb\u53d6\u7684\u884c\uff0c\u8981\u4e48\u662f\u5728\u4e8b\u52a1\u5f00\u59cb\u524d\u5df2\u7ecf\u5b58\u5728\u7684\uff0c\u8981\u4e48\u662f\u4e8b\u52a1\u81ea\u8eab\u63d2\u5165\u6216\u8005\u4fee\u6539\u7684\u3002<br \/>\n    b\u3001\u884c\u7684\u5220\u9664\u7248\u672c\u8981\u4e48\u672a\u5b9a\u4e49\uff0c\u8981\u4e48\u5927\u4e8e\u5f53\u524d\u4e8b\u52a1\u7248\u672c\u53f7\u3002\u8fd9\u53ef\u4ee5\u786e\u4fdd\u4e8b\u52a1\u8bfb\u53d6\u5230\u7684\u884c\uff0c\u5728\u4e8b\u52a1\u5f00\u59cb\u4e4b\u524d\u672a\u88ab\u5220\u9664\u3002<br \/>\n  \u53ea\u6709\u7b26\u5408\u4ee5\u4e0a\u4e24\u4e2a\u6761\u4ef6\u7684\u8bb0\u5f55\uff0c\u624d\u80fd\u8fd4\u56de\u4f5c\u4e3a\u67e5\u8be2\u7ed3\u679c\u3002<\/p>\n<\/blockquote>\n<\/li>\n<li>\n<p>insert\uff1aInnoDB \u4e3a\u65b0\u63d2\u5165\u7684\u6bcf\u4e00\u884c\u4fdd\u5b58\u5f53\u524d\u7cfb\u7edf\u7248\u672c\u53f7\u4f5c\u4e3a\u884c\u7248\u672c\u53f7\u3002<\/p>\n<\/li>\n<li>\n<p>delete\uff1aInnoDB \u4e3a\u5220\u9664\u7684\u6bcf\u4e00\u884c\u4fdd\u5b58\u5f53\u524d\u7cfb\u7edf\u7248\u672c\u53f7\u4f5c\u4e3a\u884c\u5220\u9664\u6807\u8bc6\u3002<\/p>\n<\/li>\n<li>\n<p>update\uff1aInnoDB \u4e3a\u63d2\u5165\u4e00\u884c\u65b0\u7eaa\u5f55\uff0c\u4fdd\u5b58\u5f53\u524d\u7cfb\u7edf\u7248\u672c\u53f7\u4f5c\u4e3a\u884c\u7248\u672c\u53f7\uff0c\u540c\u65f6\u4fdd\u5b58\u5f53\u524d\u7cfb\u7edf\u7248\u672c\u53f7\u5230\u539f\u6765\u7684\u884c\u4f5c\u4e3a\u884c\u5220\u9664\u6807\u8bc6\u3002<\/p>\n<\/li>\n<\/ul>\n<hr\/>\n<p>\u6b22\u8fce\u5173\u6ce8\u6211\u7684\u5fae\u4fe1\u516c\u4f17\u53f7: <strong>coderbee\u7b14\u8bb0<\/strong>\uff0c\u53ef\u4ee5\u66f4\u53ca\u65f6\u56de\u590d\u4f60\u7684\u8ba8\u8bba\u3002<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" width=\"258\" height=\"258\" src=\"https:\/\/coderbee.net\/wp-content\/uploads\/2019\/01\/coderbee-note.jpg\" class=\"alignnone size-full wp-image-1707\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e00\u3001\u9694\u79bb\u7ea7\u522b \u53c2\u8003\u4e86\u7ef4\u57fa\u767e\u79d1\uff1a\u4e8b\u52d9\u9694\u96e2 \u9694\u79bb\u7ea7\u522b\u89c4\u5b9a\u4e86\u4e00\u4e2a\u4e8b\u52a1\u4e2d\u6240\u505a\u7684\u4fee\u6539\uff0c\u54ea\u4e9b &hellip; <a href=\"https:\/\/coderbee.net\/index.php\/db\/20141020\/1056\">\u7ee7\u7eed\u9605\u8bfb <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[198,199],"_links":{"self":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/1056"}],"collection":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/comments?post=1056"}],"version-history":[{"count":3,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/1056\/revisions"}],"predecessor-version":[{"id":1059,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/1056\/revisions\/1059"}],"wp:attachment":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/media?parent=1056"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/categories?post=1056"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/tags?post=1056"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}