{"id":432,"date":"2023-05-16T00:00:40","date_gmt":"2023-05-15T16:00:40","guid":{"rendered":"http:\/\/mapleleaf666.vip\/?p=432"},"modified":"2023-06-12T12:39:15","modified_gmt":"2023-06-12T04:39:15","slug":"mvcc","status":"publish","type":"post","link":"http:\/\/mapleleaf666.vip\/?p=432","title":{"rendered":"MVCC\u5b66\u4e60\u603b\u7ed3"},"content":{"rendered":"\n

MVCC\u4f5c\u4e3a\u6570\u636e\u5e93\u3001\u5927\u6570\u636e\u6280\u672f\u7684\u91cd\u8981\u6982\u5ff5\uff0c\u5fc5\u987b\u8981\u638c\u63e1\u5176\u539f\u7406\uff0c\u672c\u6587\u4e3b\u8981\u53c2\u8003\u770b\u4e00\u904d\u5c31\u7406\u89e3\uff1aMVCC\u539f\u7406\u8be6\u89e3 – \u6398\u91d1 (juejin.cn)<\/a>\u5bf9\u8be5\u77e5\u8bc6\u70b9\u8fdb\u884c\u603b\u7ed3\uff0c\u5e76\u6dfb\u52a0\u4e86\u4e00\u4e9b\u81ea\u5df1\u7684\u7406\u89e3\u3002<\/p>\n\n\n\n

\u6570\u636e\u5e93\u57fa\u7840\u77e5\u8bc6\u56de\u987e<\/h2>\n\n\n\n

\u4ec0\u4e48\u662f\u4e8b\u52a1<\/h3>\n\n\n\n

\u4e8b\u52a1\uff1a\u6307\u4e00\u7ec4\u6570\u636e\u5e93\u64cd\u4f5c\uff0c\u8fd9\u7ec4\u64cd\u4f5c\u8981\u4e48\u5168\u90e8\u6267\u884c\u6210\u529f\uff0c\u8981\u4e48\u5168\u90e8\u4e0d\u6267\u884c\uff0c\u4e0d\u80fd\u53ea\u6267\u884c\u5176\u4e2d\u7684\u4e00\u90e8\u5206\u3002\u4e8b\u52a1\u901a\u5e38\u7528\u4e8e\u786e\u4fdd\u6570\u636e\u5e93\u7684\u4e00\u81f4\u6027\u548c\u5b8c\u6574\u6027\uff0c\u4ee5\u53ca\u4fdd\u8bc1\u591a\u4e2a\u7528\u6237\u540c\u65f6\u5bf9\u6570\u636e\u5e93\u8fdb\u884c\u8bbf\u95ee\u65f6\u6570\u636e\u7684\u6b63\u786e\u6027\u3002<\/p>\n\n\n\n

\n

\u6848\u4f8b\uff1a<\/p>\n\n\n\n

\u5047\u8bbe\u5ba2\u6237\u9700\u8981\u4ece\u8d26\u6237A\u4e2d\u8f6c\u79fb100\u5143\u5230\u8d26\u6237B\u4e2d\u3002\u8fd9\u4e2a\u8f6c\u8d26\u64cd\u4f5c\u53ef\u80fd\u6d89\u53ca\u5230\u4e24\u4e2a\u6570\u636e\u5e93\u64cd\u4f5c\uff1a\u4ece\u8d26\u6237A\u4e2d\u6263\u9664100\u5143\uff0c\u540c\u65f6\u5411\u8d26\u6237B\u4e2d\u589e\u52a0100\u5143\u3002
\u5982\u679c\u6ca1\u6709\u4f7f\u7528\u4e8b\u52a1\uff0c\u5f53\u6263\u9664\u8d26\u6237A\u4e2d\u7684100\u5143\u65f6\uff0c\u7cfb\u7edf\u53d1\u751f\u6545\u969c\u6216\u7a0b\u5e8f\u51fa\u73b0\u9519\u8bef\uff0c\u53ef\u80fd\u4f1a\u5bfc\u81f4\u6570\u636e\u5e93\u4e2d\u51fa\u73b0\u4e0d\u4e00\u81f4\u7684\u6570\u636e\uff0c\u5373\u8d26\u6237A\u4e2d\u6263\u9664\u4e86100\u5143\uff0c\u4f46\u8d26\u6237B\u4e2d\u5e76\u6ca1\u6709\u589e\u52a0100\u5143\u3002\u8fd9\u5c06\u5bfc\u81f4\u6570\u636e\u7684\u4e22\u5931\u548c\u4e0d\u4e00\u81f4\u6027\u3002<\/p>\n<\/blockquote>\n\n\n\n

\u4e8b\u52a1\u7684\u56db\u5927\u7279\u6027<\/h3>\n\n\n\n
    \n
  • \u539f\u5b50\u6027(Atomicity)\uff1a\u4e8b\u52a1\u4f5c\u4e3a\u4e00\u4e2a\u6574\u4f53\u88ab\u6267\u884c\uff0c\u5305\u542b\u5728\u5176\u4e2d\u7684\u5bf9\u6570\u636e\u5e93\u7684\u64cd\u4f5c\u8981\u4e48\u5168\u90e8\u90fd\u6267\u884c\uff0c\u8981\u4e48\u90fd\u4e0d\u6267\u884c\u3002<\/li>\n\n\n\n
  • \u4e00\u81f4\u6027(Consistency)\uff1a\u6307\u5728\u4e8b\u52a1\u5f00\u59cb\u4e4b\u524d\u548c\u4e8b\u52a1\u7ed3\u675f\u4ee5\u540e\uff0c\u6570\u636e\u4e0d\u4f1a\u88ab\u7834\u574f\uff0c\u5047\u5982 A \u8d26\u6237\u7ed9 B \u8d26\u6237\u8f6c 10 \u5757\u94b1\uff0c\u4e0d\u7ba1\u6210\u529f\u4e0e\u5426\uff0cA \u548c B \u7684\u603b\u91d1\u989d\u662f\u4e0d\u53d8\u7684\u3002<\/li>\n\n\n\n
  • \u9694\u79bb\u6027(Isolation)\uff1a\u591a\u4e2a\u4e8b\u52a1\u5e76\u53d1\u8bbf\u95ee\u65f6\uff0c\u4e8b\u52a1\u4e4b\u95f4\u662f\u76f8\u4e92\u9694\u79bb\u7684\uff0c\u4e00\u4e2a\u4e8b\u52a1\u4e0d\u5e94\u8be5\u88ab\u5176\u4ed6\u4e8b\u52a1\u5e72\u6270\uff0c\u591a\u4e2a\u5e76\u53d1\u4e8b\u52a1\u4e4b\u95f4\u8981\u76f8\u4e92\u9694\u79bb\u3002<\/li>\n\n\n\n
  • \u6301\u4e45\u6027(Durability)\uff1a\u8868\u793a\u4e8b\u52a1\u5b8c\u6210\u63d0\u4ea4\u540e\uff0c\u8be5\u4e8b\u52a1\u5bf9\u6570\u636e\u5e93\u6240\u4f5c\u7684\u64cd\u4f5c\u66f4\u6539\uff0c\u5c06\u6301\u4e45\u5730\u4fdd\u5b58\u5728\u6570\u636e\u5e93\u4e4b\u4e2d\u3002 <\/li>\n<\/ul>\n\n\n\n

    \u4e8b\u52a1\u5e76\u53d1\u5b58\u5728\u7684\u95ee\u9898<\/h3>\n\n\n\n
      \n
    • \u810f\u8bfb\uff08Dirty Read\uff09\uff1a\u4e00\u4e2a\u4e8b\u52a1\u8bfb\u53d6\u4e86\u53e6\u4e00\u4e2a\u4e8b\u52a1\u8fd8\u672a\u63d0\u4ea4\u7684\u6570\u636e\u3002\u5982\u679c\u7b2c\u4e8c\u4e2a\u4e8b\u52a1\u56de\u6eda\uff0c\u90a3\u4e48\u7b2c\u4e00\u4e2a\u4e8b\u52a1\u6240\u8bfb\u53d6\u7684\u6570\u636e\u5c31\u662f\u65e0\u6548\u7684\u3002<\/li>\n\n\n\n
    • \u5e7b\u8bfb\uff08Phantom Read\uff09\uff1a\u5728\u4e00\u4e2a\u4e8b\u52a1\u4e2d\uff0c\u591a\u6b21\u8bfb\u53d6\u4e00\u7ec4\u6570\u636e\uff0c\u5728\u8fd9\u4e9b\u8bfb\u53d6\u4e4b\u95f4\uff0c\u53e6\u4e00\u4e2a\u4e8b\u52a1\u63d2\u5165\u4e86\u7b26\u5408\u6761\u4ef6\u7684\u65b0\u6570\u636e\u3002\u56e0\u6b64\uff0c\u5728\u4e8b\u52a1\u7684\u4e24\u6b21\u8bfb\u53d6\u4e4b\u95f4\uff0c\u6570\u636e\u7684\u603b\u91cf\u53d1\u751f\u4e86\u53d8\u5316\uff0c\u8fd9\u4f1a\u5bfc\u81f4\u524d\u540e\u4e24\u6b21\u8bfb\u53d6\u7684\u7ed3\u679c\u4e0d\u4e00\u81f4\u3002<\/li>\n\n\n\n
    • \u4e0d\u53ef\u91cd\u590d\u8bfb\uff08Non-Repeatable Read\uff09\uff1a\u5728\u4e00\u4e2a\u4e8b\u52a1\u4e2d\uff0c\u591a\u6b21\u8bfb\u53d6\u540c\u4e00\u4e2a\u6570\u636e\uff0c\u5728\u8fd9\u4e9b\u8bfb\u53d6\u4e4b\u95f4\uff0c\u53e6\u4e00\u4e2a\u4e8b\u52a1\u4fee\u6539\u4e86\u8be5\u6570\u636e\u3002\u56e0\u6b64\uff0c\u5728\u4e8b\u52a1\u7684\u4e24\u6b21\u8bfb\u53d6\u4e4b\u95f4\uff0c\u6570\u636e\u7684\u503c\u53d1\u751f\u4e86\u53d8\u5316\uff0c\u8fd9\u4f1a\u5bfc\u81f4\u524d\u540e\u4e24\u6b21\u8bfb\u53d6\u7684\u7ed3\u679c\u4e0d\u4e00\u81f4\u3002<\/li>\n<\/ul>\n\n\n\n

      \u89e3\u51b3\u65b9\u6cd5\uff1a\u4e3a\u4e86\u907f\u514d\u4ee5\u4e0a\u95ee\u9898\uff0c\u6570\u636e\u5e93\u63d0\u4f9b\u4e86\u56db\u79cd\u9694\u79bb\u7ea7\u522b\uff08Isolation Level\uff09\uff0c\u5305\u62ec\u672a\u63d0\u4ea4\u8bfb\uff08Read Uncommitted\uff09\u3001\u63d0\u4ea4\u8bfb\uff08Read Committed\uff09\u3001\u53ef\u91cd\u590d\u8bfb\uff08Repeatable Read\uff09\u548c\u4e32\u884c\u5316\uff08Serializable\uff09\u3002\u4e0d\u540c\u7684\u9694\u79bb\u7ea7\u522b\u63d0\u4f9b\u4e0d\u540c\u7684\u4fdd\u62a4\u7a0b\u5ea6\uff0c\u9009\u62e9\u5408\u9002\u7684\u9694\u79bb\u7ea7\u522b\u53ef\u4ee5\u5728\u6ee1\u8db3\u4e1a\u52a1\u9700\u6c42\u7684\u524d\u63d0\u4e0b\u63d0\u9ad8\u6570\u636e\u5e93\u7684\u6027\u80fd\u548c\u5e76\u53d1\u6027\u80fd\u3002<\/p>\n\n\n\n

      \u56db\u5927\u9694\u79bb\u7ea7\u522b<\/h3>\n\n\n\n
        \n
      • \u672a\u63d0\u4ea4\u8bfb\uff08Read Uncommitted\uff09\uff1a\u5728\u8fd9\u4e2a\u9694\u79bb\u7ea7\u522b\u4e0b\uff0c\u4e00\u4e2a\u4e8b\u52a1\u53ef\u4ee5\u8bfb\u53d6\u5230\u53e6\u4e00\u4e2a\u4e8b\u52a1\u8fd8\u672a\u63d0\u4ea4\u7684\u6570\u636e\u3002\u8fd9\u53ef\u80fd\u4f1a\u5bfc\u81f4\u810f\u8bfb\u3001\u4e0d\u53ef\u91cd\u590d\u8bfb\u548c\u5e7b\u8bfb\u95ee\u9898\u3002 <\/li>\n\n\n\n
      • \u5df2\u63d0\u4ea4\u8bfb\uff08Read Committed\uff09\uff1a\u5728\u8fd9\u4e2a\u9694\u79bb\u7ea7\u522b\u4e0b\uff0c\u4e00\u4e2a\u4e8b\u52a1\u53ea\u80fd\u8bfb\u53d6\u5230\u5df2\u7ecf\u63d0\u4ea4\u7684\u6570\u636e\u3002\u8fd9\u53ef\u4ee5\u907f\u514d\u810f\u8bfb\u95ee\u9898\uff0c\u4f46\u53ef\u80fd\u4f1a\u5bfc\u81f4\u4e0d\u53ef\u91cd\u590d\u8bfb\u548c\u5e7b\u8bfb\u95ee\u9898\u3002 <\/li>\n\n\n\n
      • \u53ef\u91cd\u590d\u8bfb\uff08Repeatable Read\uff09\uff1a\u5728\u8fd9\u4e2a\u9694\u79bb\u7ea7\u522b\u4e0b\uff0c\u4e00\u4e2a\u4e8b\u52a1\u5728\u6267\u884c\u8fc7\u7a0b\u4e2d\u591a\u6b21\u8bfb\u53d6\u540c\u4e00\u6570\u636e\uff0c\u4f1a\u4fdd\u8bc1\u591a\u6b21\u8bfb\u53d6\u5230\u7684\u6570\u636e\u662f\u4e00\u81f4\u7684\uff0c\u5373\u4f7f\u5728\u4e8b\u52a1\u6267\u884c\u671f\u95f4\u6709\u5176\u4ed6\u4e8b\u52a1\u5bf9\u8fd9\u4e9b\u6570\u636e\u8fdb\u884c\u4e86\u4fee\u6539\u3002\u8fd9\u53ef\u4ee5\u907f\u514d\u810f\u8bfb\u548c\u4e0d\u53ef\u91cd\u590d\u8bfb\u95ee\u9898\uff0c\u4f46\u4ecd\u53ef\u80fd\u4f1a\u51fa\u73b0\u5e7b\u8bfb\u95ee\u9898\u3002<\/li>\n\n\n\n
      • \u4e32\u884c\u5316\uff08Serializable\uff09\uff1a\u5728\u8fd9\u4e2a\u9694\u79bb\u7ea7\u522b\u4e0b\uff0c\u6240\u6709\u4e8b\u52a1\u7684\u6267\u884c\u90fd\u662f\u4e32\u884c\u7684\uff0c\u6bcf\u4e2a\u4e8b\u52a1\u5fc5\u987b\u7b49\u5f85\u524d\u4e00\u4e2a\u4e8b\u52a1\u5b8c\u6210\u624d\u80fd\u6267\u884c\u3002\u8fd9\u53ef\u4ee5\u5b8c\u5168\u907f\u514d\u5e76\u53d1\u95ee\u9898\uff0c\u4f46\u53ef\u80fd\u4f1a\u964d\u4f4e\u6570\u636e\u5e93\u7684\u5e76\u53d1\u6027\u80fd\u3002<\/li>\n<\/ul>\n\n\n\n

        \u6570\u636e\u5e93\u4fdd\u8bc1\u4e8b\u52a1\u7684\u9694\u79bb\u6027\u7684\u65b9\u5f0f<\/h3>\n\n\n\n
          \n
        • \u9501\u673a\u5236\uff1a\u6570\u636e\u5e93\u4f7f\u7528\u9501\u6765\u63a7\u5236\u5e76\u53d1\u4e8b\u52a1\u5bf9\u6570\u636e\u7684\u8bbf\u95ee\u3002\u5f53\u4e00\u4e2a\u4e8b\u52a1\u5bf9\u67d0\u4e2a\u6570\u636e\u8fdb\u884c\u4fee\u6539\u65f6\uff0c\u6570\u636e\u5e93\u4f1a\u5bf9\u8be5\u6570\u636e\u8fdb\u884c\u52a0\u9501\uff0c\u5176\u4ed6\u4e8b\u52a1\u4e0d\u80fd\u5bf9\u8be5\u6570\u636e\u8fdb\u884c\u4fee\u6539\uff0c\u76f4\u5230\u6301\u6709\u9501\u7684\u4e8b\u52a1\u63d0\u4ea4\u6216\u56de\u6eda\u3002\u8fd9\u53ef\u4ee5\u907f\u514d\u5e76\u53d1\u95ee\u9898\uff0c\u4fdd\u8bc1\u4e8b\u52a1\u4e4b\u95f4\u7684\u9694\u79bb\u6027\u3002<\/li>\n\n\n\n
        • \u591a\u7248\u672c\u5e76\u53d1\u63a7\u5236\uff08MVCC\uff09\uff1aMVCC\u662f\u4e00\u79cd\u5e76\u53d1\u63a7\u5236\u6280\u672f\uff0c\u5b83\u901a\u8fc7\u4e3a\u6bcf\u4e2a\u4e8b\u52a1\u521b\u5efa\u4e00\u4e2a\u72ec\u7acb\u7684\u6570\u636e\u7248\u672c\u6765\u5b9e\u73b0\u4e8b\u52a1\u7684\u9694\u79bb\u6027\u3002\u5f53\u4e00\u4e2a\u4e8b\u52a1\u5bf9\u6570\u636e\u8fdb\u884c\u4fee\u6539\u65f6\uff0c\u6570\u636e\u5e93\u4f1a\u521b\u5efa\u4e00\u4e2a\u65b0\u7684\u7248\u672c\uff0c\u5e76\u5c06\u8be5\u7248\u672c\u5206\u914d\u7ed9\u8be5\u4e8b\u52a1\u3002\u5176\u4ed6\u4e8b\u52a1\u4ecd\u7136\u53ef\u4ee5\u8bfb\u53d6\u65e7\u7248\u672c\u7684\u6570\u636e\uff0c\u8fd9\u53ef\u4ee5\u907f\u514d\u810f\u8bfb\u3001\u4e0d\u53ef\u91cd\u590d\u8bfb\u548c\u5e7b\u8bfb\u95ee\u9898\u3002<\/li>\n\n\n\n
        • \u4e8b\u52a1\u65e5\u5fd7\uff1a\u6570\u636e\u5e93\u4f1a\u5c06\u6240\u6709\u4e8b\u52a1\u7684\u64cd\u4f5c\u8bb0\u5f55\u5230\u4e8b\u52a1\u65e5\u5fd7\u4e2d\u3002\u5982\u679c\u67d0\u4e2a\u4e8b\u52a1\u9700\u8981\u56de\u6eda\uff0c\u6570\u636e\u5e93\u53ef\u4ee5\u4f7f\u7528\u4e8b\u52a1\u65e5\u5fd7\u4e2d\u7684\u4fe1\u606f\u5c06\u6570\u636e\u5e93\u6062\u590d\u5230\u4e8b\u52a1\u5f00\u59cb\u4e4b\u524d\u7684\u72b6\u6001\uff0c\u8fd9\u53ef\u4ee5\u907f\u514d\u810f\u8bfb\u95ee\u9898\u3002<\/li>\n\n\n\n
        • \u4e8b\u52a1\u9694\u79bb\u7ea7\u522b\uff1a\u6570\u636e\u5e93\u63d0\u4f9b\u4e86\u56db\u79cd\u4e8b\u52a1\u9694\u79bb\u7ea7\u522b\uff0c\u53ef\u4ee5\u6839\u636e\u5177\u4f53\u7684\u4e1a\u52a1\u9700\u6c42\u9009\u62e9\u9002\u5f53\u7684\u9694\u79bb\u7ea7\u522b\u3002\u4e0d\u540c\u7684\u9694\u79bb\u7ea7\u522b\u63d0\u4f9b\u4e0d\u540c\u7684\u9694\u79bb\u7a0b\u5ea6\uff0c\u4ece\u672a\u63d0\u4ea4\u8bfb\u5230\u4e32\u884c\u5316\uff0c\u6bcf\u4e2a\u9694\u79bb\u7ea7\u522b\u90fd\u53ef\u4ee5\u907f\u514d\u4e00\u4e9b\u5e76\u53d1\u95ee\u9898\u3002<\/li>\n<\/ul>\n\n\n\n

          \u5176\u4e2dMVCC\u4fbf\u662f\u6211\u4eec\u8fd9\u91cc\u7684\u4e3b\u89d2\uff01<\/strong><\/p>\n\n\n\n

          MVCC\u6982\u5ff5\u4ecb\u7ecd<\/h2>\n\n\n\n

          \u4ec0\u4e48\u662fMVCC<\/h3>\n\n\n\n

          MVCC\uff0c\u5373 Multi-Version Concurrency Control \uff08\u591a\u7248\u672c\u5e76\u53d1\u63a7\u5236\uff09\u3002\u5b83\u662f\u4e00\u79cd\u5e76\u53d1\u63a7\u5236\u7684\u65b9\u6cd5\uff0c\u4e00\u822c\u5728\u6570\u636e\u5e93\u7ba1\u7406\u7cfb\u7edf\u4e2d\uff0c\u5b9e\u73b0\u5bf9\u6570\u636e\u5e93\u7684\u5e76\u53d1\u8bbf\u95ee\uff0c\u5728\u7f16\u7a0b\u8bed\u8a00\u4e2d\u5b9e\u73b0\u4e8b\u52a1\u5185\u5b58\u3002<\/p>\n\n\n\n

          \u5177\u4f53\u5185\u5bb9\uff1f<\/h3>\n\n\n\n

          \u901a\u4fd7\u7684\u8bb2\uff0c\u6570\u636e\u5e93\u4e2d\u540c\u65f6\u5b58\u5728\u591a\u4e2a\u7248\u672c\u7684\u6570\u636e\uff0c\u5e76\u4e0d\u662f\u6574\u4e2a\u6570\u636e\u5e93\u7684\u591a\u4e2a\u7248\u672c\uff0c\u800c\u662f\u67d0\u4e00\u6761\u8bb0\u5f55\u7684\u591a\u4e2a\u7248\u672c\u540c\u65f6\u5b58\u5728\uff0c\u5728\u67d0\u4e2a\u4e8b\u52a1\u5bf9\u5176\u8fdb\u884c\u64cd\u4f5c\u7684\u65f6\u5019\uff0c\u9700\u8981\u67e5\u770b\u8fd9\u4e00\u6761\u8bb0\u5f55\u7684\u9690\u85cf\u5217\u4e8b\u52a1\u7248\u672c id\uff0c\u6bd4\u5bf9\u4e8b\u52a1 id \u5e76\u6839\u636e\u4e8b\u7269\u9694\u79bb\u7ea7\u522b\u53bb\u5224\u65ad\u8bfb\u53d6\u54ea\u4e2a\u7248\u672c\u7684\u6570\u636e\u3002<\/p>\n\n\n\n

          \u4e3a\u4ec0\u4e48\u8981\u6709MVCC<\/h3>\n\n\n\n

          \u907f\u514d\u9501\u7ade\u4e89\uff1a\u5728\u4f20\u7edf\u7684\u6570\u636e\u5e93\u5e76\u53d1\u63a7\u5236\u4e2d\uff0c\u5f53\u591a\u4e2a\u4e8b\u52a1\u540c\u65f6\u8bbf\u95ee\u540c\u4e00\u6570\u636e\u65f6\uff0c\u6570\u636e\u5e93\u4f1a\u5bf9\u8be5\u6570\u636e\u8fdb\u884c\u52a0\u9501\uff0c\u4ece\u800c\u907f\u514d\u5e76\u53d1\u95ee\u9898\u3002\u4f46\u662f\uff0c\u52a0\u9501\u4f1a\u5bfc\u81f4\u9501\u7ade\u4e89\uff0c\u964d\u4f4e\u6570\u636e\u5e93\u7684\u5e76\u53d1\u6027\u80fd\u3002\u800cMVCC\u53ef\u4ee5\u907f\u514d\u9501\u7ade\u4e89\uff0c\u56e0\u4e3a\u5b83\u662f\u901a\u8fc7\u4e3a\u6bcf\u4e2a\u4e8b\u52a1\u521b\u5efa\u4e00\u4e2a\u72ec\u7acb\u7684\u6570\u636e\u7248\u672c\u6765\u5b9e\u73b0\u5e76\u53d1\u63a7\u5236\u7684\u3002<\/p>\n\n\n\n

          MVCC\u7684\u4f18\u70b9<\/h3>\n\n\n\n

          \u5e76\u53d1\u6027\u80fd\u66f4\u9ad8\u3001\u8bfb\u5199\u64cd\u4f5c\u4e92\u4e0d\u5e72\u6270\u3001\u652f\u6301\u5386\u53f2\u6570\u636e\u67e5\u8be2\u3001\u4e0d\u4f1a\u51fa\u73b0\u6b7b\u9501\u3002<\/p>\n\n\n\n

          MVCC\u4e0e\u6570\u636e\u5e93\u9694\u79bb\u7ea7\u522b<\/h3>\n\n\n\n

          \u6570\u636e\u5e93\u9694\u79bb\u7ea7\u522b\u8bfb\u5df2\u63d0\u4ea4\u3001\u53ef\u91cd\u590d\u8bfb<\/strong>\u90fd\u662f\u57fa\u4e8e MVCC \u5b9e\u73b0\u7684\uff0c\u76f8\u5bf9\u4e8e\u52a0\u9501\u7b80\u5355\u7c97\u66b4\u7684\u65b9\u5f0f\uff0c\u5b83\u7528\u66f4\u597d\u7684\u65b9\u5f0f\u53bb\u5904\u7406\u8bfb\u5199\u51b2\u7a81\uff0c\u80fd\u6709\u6548\u63d0\u9ad8\u6570\u636e\u5e93\u5e76\u53d1\u6027\u80fd\u3002<\/p>\n\n\n\n

          MVCC\u6838\u5fc3\u6982\u5ff5<\/h2>\n\n\n\n

          \u7248\u672c\u53f7<\/h3>\n\n\n\n

          \u4e8b\u52a1\u6bcf\u6b21\u5f00\u542f\u524d\uff0c\u90fd\u4f1a\u4ece\u6570\u636e\u5e93\u83b7\u5f97\u4e00\u4e2a\u81ea\u589e\u957f\u7684\u4e8b\u52a1 ID\uff0c\u53ef\u4ee5\u4ece\u4e8b\u52a1 ID \u5224\u65ad\u4e8b\u52a1\u7684\u6267\u884c\u5148\u540e\u987a\u5e8f\u3002\u8fd9\u5c31\u662f\u4e8b\u52a1\u7248\u672c\u53f7\u3002<\/p>\n\n\n\n

          \u9690\u5f0f\u5b57\u6bb5<\/h3>\n\n\n\n

          \u5bf9\u4e8e InnoDB \u5b58\u50a8\u5f15\u64ce\uff0c\u6bcf\u4e00\u884c\u8bb0\u5f55\u90fd\u6709\u4e24\u4e2a\u9690\u85cf\u5217 trx_id\u3001roll_pointer\uff0c\u5982\u679c\u8868\u4e2d\u6ca1\u6709\u4e3b\u952e\u548c\u975e NULL \u552f\u4e00\u952e\u65f6\uff0c\u5219\u8fd8\u4f1a\u6709\u7b2c\u4e09\u4e2a\u9690\u85cf\u7684\u4e3b\u952e\u5217 row_id\u3002<\/p>\n\n\n\n

          \u5feb\u7167\u8bfb<\/h3>\n\n\n\n

          \u8bfb\u53d6\u7684\u662f\u8bb0\u5f55\u6570\u636e\u7684\u53ef\u89c1\u7248\u672c\uff08\u6709\u65e7\u7684\u7248\u672c\uff09\u3002\u4e0d\u52a0\u9501,\u666e\u901a\u7684 select \u8bed\u53e5\u90fd\u662f\u5feb\u7167\u8bfb,\u5982\uff1a<\/p>\n\n\n\n

          \"\"<\/div><\/figure>\n\n\n\n

          \u5f53\u524d\u8bfb<\/h3>\n\n\n\n

          \u8bfb\u53d6\u7684\u662f\u8bb0\u5f55\u6570\u636e\u7684\u6700\u65b0\u7248\u672c\uff0c\u663e\u5f0f\u52a0\u9501\u7684\u90fd\u662f\u5f53\u524d\u8bfb<\/p>\n\n\n\n

          \"\"<\/div><\/figure>\n\n\n\n

          undo log<\/h3>\n\n\n\n

          \u80cc\u666f<\/h4>\n\n\n\n

          \u5728MVCC\u4e2d\uff0c\u4e3a\u4e86\u4fdd\u8bc1\u4e8b\u52a1\u7684\u9694\u79bb\u6027\uff0c\u6bcf\u4e2a\u4e8b\u52a1\u90fd\u53ef\u4ee5\u770b\u5230\u81ea\u5df1\u542f\u52a8\u4e4b\u524d\u7684\u6570\u636e\u7248\u672c\uff0c\u8fd9\u5c31\u8981\u6c42\u6570\u636e\u5e93\u9700\u8981\u7ef4\u62a4\u591a\u4e2a\u7248\u672c\u7684\u6570\u636e\u3002\u4e3a\u4e86\u5b9e\u73b0\u8fd9\u4e00\u70b9\uff0cMVCC\u91c7\u7528\u4e86\u4e00\u79cd\u540d\u4e3a\u201cundo log\u201d\u7684\u673a\u5236\uff0c\u5b83\u8bb0\u5f55\u4e86\u6bcf\u4e2a\u4e8b\u52a1\u6240\u4fee\u6539\u7684\u6570\u636e\uff0c\u4ee5\u53ca\u4fee\u6539\u524d\u7684\u6570\u636e\u7248\u672c\u3002<\/p>\n\n\n\n

          undo log\u7684\u4f5c\u7528<\/h4>\n\n\n\n

          undo log\u662f\u4e00\u79cd\u65e5\u5fd7\uff0c\u7528\u4e8e\u8bb0\u5f55\u4e8b\u52a1\u6240\u4fee\u6539\u7684\u6570\u636e\u548c\u4fee\u6539\u524d\u7684\u6570\u636e\u7248\u672c\u3002\u5f53\u4e8b\u52a1\u9700\u8981\u56de\u6eda\u65f6\uff0c\u6570\u636e\u5e93\u53ef\u4ee5\u4f7f\u7528undo log\u6765\u8fd8\u539f\u4fee\u6539\u524d\u7684\u6570\u636e\u3002undo log\u8fd8\u53ef\u4ee5\u7528\u4e8e\u5b9e\u73b0\u6570\u636e\u5e93\u7684\u5d29\u6e83\u6062\u590d\uff0c\u4fdd\u8bc1\u6570\u636e\u5e93\u5728\u5d29\u6e83\u540e\u80fd\u591f\u6b63\u786e\u5730\u6062\u590d\u5230\u4e8b\u52a1\u542f\u52a8\u4e4b\u524d\u7684\u72b6\u6001\u3002<\/p>\n\n\n\n

          undo log\u7684\u7ed3\u6784<\/h4>\n\n\n\n
            \n
          • \u4e8b\u52a1ID\uff1a\u6bcf\u4e2aundo log\u90fd\u4e0e\u4e00\u4e2a\u4e8b\u52a1\u76f8\u5173\u8054\uff0c\u4e8b\u52a1ID\u7528\u4e8e\u6807\u8bc6\u8be5undo log\u6240\u5c5e\u7684\u4e8b\u52a1\u3002<\/li>\n\n\n\n
          • \u64cd\u4f5c\u7c7b\u578b\uff1aundo log\u8bb0\u5f55\u4e86\u6bcf\u4e2a\u64cd\u4f5c\u7684\u7c7b\u578b\uff0c\u5982INSERT\u3001UPDATE\u3001DELETE\u7b49\u3002<\/li>\n\n\n\n
          • \u6570\u636e\uff1aundo log\u8bb0\u5f55\u4e86\u4e8b\u52a1\u6240\u4fee\u6539\u7684\u6570\u636e\u7684\u503c\u3002<\/li>\n\n\n\n
          • \u64cd\u4f5c\u524d\u7684\u6570\u636e\u7248\u672c\uff1aundo log\u8fd8\u8bb0\u5f55\u4e86\u4e8b\u52a1\u6240\u4fee\u6539\u7684\u6570\u636e\u5728\u4fee\u6539\u4e4b\u524d\u7684\u7248\u672c\uff0c\u7528\u4e8e\u5b9e\u73b0MVCC\u3002<\/li>\n<\/ul>\n\n\n\n

            undo log\u901a\u5e38\u4ee5\u94fe\u8868\u7684\u5f62\u5f0f\u7ec4\u7ec7\uff0c\u6bcf\u4e2a\u4e8b\u52a1\u6240\u4fee\u6539\u7684\u6570\u636e\u5bf9\u5e94\u4e00\u4e2aundo log\u3002\u5f53\u4e8b\u52a1\u63d0\u4ea4\u6216\u56de\u6eda\u65f6\uff0c\u6570\u636e\u5e93\u4f1a\u6309\u7167undo log\u7684\u987a\u5e8f\u5bf9\u6570\u636e\u8fdb\u884c\u66f4\u65b0\u6216\u8fd8\u539f\u3002<\/p>\n\n\n\n

            \u5f53\u4e00\u4e2a\u4e8b\u52a1\u9700\u8981\u4fee\u6539\u6570\u636e\u65f6\uff0c\u6570\u636e\u5e93\u4f1a\u521b\u5efa\u4e00\u4e2a\u65b0\u7684\u6570\u636e\u7248\u672c\uff0c\u5e76\u5c06\u8be5\u6570\u636e\u7248\u672c\u7684\u7248\u672c\u53f7\u548c\u4e8b\u52a1\u7684\u542f\u52a8\u65f6\u95f4\u76f8\u5173\u8054\u3002\u540c\u65f6\uff0c\u6570\u636e\u5e93\u4f1a\u5728undo log\u4e2d\u8bb0\u5f55\u8be5\u6570\u636e\u4fee\u6539\u524d\u7684\u7248\u672c\uff0c\u4ee5\u4fbf\u56de\u6eda\u4e8b\u52a1\u65f6\u80fd\u591f\u8fd8\u539f\u4fee\u6539\u524d\u7684\u6570\u636e\u3002\u5f53\u4e8b\u52a1\u63d0\u4ea4\u65f6\uff0c\u6570\u636e\u5e93\u4f1a\u5c06\u8be5\u4e8b\u52a1\u6240\u521b\u5efa\u7684\u6240\u6709\u6570\u636e\u7248\u672c\u548c\u76f8\u5173\u7684undo log\u63d0\u4ea4\u5230\u6570\u636e\u5e93\u4e2d\uff0c\u4ece\u800c\u5b9e\u73b0\u4e8b\u52a1\u7684\u6301\u4e45\u5316\u3002<\/p>\n\n\n\n

            \u7248\u672c\u94fe<\/h3>\n\n\n\n

            \u57fa\u672c\u6982\u5ff5<\/h4>\n\n\n\n

            \u591a\u4e2a\u4e8b\u52a1\u5e76\u884c\u64cd\u4f5c\u67d0\u4e00\u884c\u6570\u636e\u65f6\uff0c\u4e0d\u540c\u4e8b\u52a1\u5bf9\u8be5\u884c\u6570\u636e\u7684\u4fee\u6539\u4f1a\u4ea7\u751f\u591a\u4e2a\u7248\u672c\uff0c\u7136\u540e\u901a\u8fc7\u56de\u6eda\u6307\u9488\uff08roll_pointer\uff09\uff0c\u8fde\u6210\u4e00\u4e2a\u94fe\u8868\uff0c\u8fd9\u4e2a\u94fe\u8868\u5c31\u79f0\u4e3a\u7248\u672c\u94fe\u3002\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n\n\n\n

            \"\"<\/div><\/figure>\n\n\n\n

            \u7248\u672c\u94fe\u7684\u7ed3\u6784<\/h4>\n\n\n\n

            \u7248\u672c\u94fe\u901a\u5e38\u4ee5\u94fe\u8868\u7684\u5f62\u5f0f\u7ec4\u7ec7\uff0c\u6bcf\u4e2a\u6570\u636e\u5bf9\u8c61\u5bf9\u5e94\u4e00\u4e2a\u7248\u672c\u94fe\u3002\u94fe\u8868\u4e2d\u7684\u6bcf\u4e2a\u8282\u70b9\u8868\u793a\u4e00\u4e2a\u6570\u636e\u7248\u672c\uff0c\u5305\u62ec\u4ee5\u4e0b\u51e0\u4e2a\u90e8\u5206\uff1a<\/p>\n\n\n\n

              \n
            • \u7248\u672c\u53f7\uff1a\u6bcf\u4e2a\u7248\u672c\u90fd\u6709\u4e00\u4e2a\u7248\u672c\u53f7\uff0c\u8868\u793a\u8be5\u7248\u672c\u6570\u636e\u7684\u521b\u5efa\u65f6\u95f4\u3002\u5982\u53f3\u56fe\u7684trx_id\u3002<\/li>\n\n\n\n
            • \u6570\u636e\uff1a\u6bcf\u4e2a\u7248\u672c\u90fd\u5305\u542b\u4e00\u4efd\u5b8c\u6574\u7684\u6570\u636e\u526f\u672c\u3002<\/li>\n\n\n\n
            • \u56de\u6eda\u6307\u9488\uff1a\u6bcf\u4e2a\u7248\u672c\u8282\u70b9\u90fd\u5305\u542b\u4e00\u4e2a\u6307\u5411\u524d\u9a71\u7248\u672c\u548c\u540e\u7ee7\u7248\u672c\u7684\u6307\u9488\uff0c\u7528\u4e8e\u904d\u5386\u7248\u672c\u94fe\u3002\u5982\u56fe\u7684roll_pointer\u3002<\/li>\n<\/ul>\n\n\n\n

              \u5e94\u7528\u6848\u4f8b<\/h4>\n\n\n\n

              \u5bf9\u4e0a\u9762\u7684\u7248\u672c\u94fe\u6211\u4eec\u8fdb\u884c\u5206\u6790\uff1a
              1.\u5047\u8bbe\u73b0\u5728\u6709\u4e00\u5f20 core_user \u8868\uff0c\u8868\u91cc\u9762\u6709\u4e00\u6761\u6570\u636e,id \u4e3a 1\uff0c\u540d\u5b57\u4e3a\u5b59\u6743\u3002
              2.\u73b0\u5728\u5f00\u542f\u4e00\u4e2a\u4e8b\u52a1 A\uff1a\u5bf9 core_user \u8868\u6267\u884cupdate core_user set name =”\u66f9\u64cd” where id=1,\u4f1a\u8fdb\u884c\u5982\u4e0b\u6d41\u7a0b\u64cd\u4f5c\uff1a\u9996\u5148\u83b7\u5f97\u4e00\u4e2a\u4e8b\u52a1 ID=100\uff1b\u7136\u540e\u628a core_user \u8868\u4fee\u6539\u524d\u7684\u6570\u636e,\u62f7\u8d1d\u5230 undo log\uff1b\u4fee\u6539 core_user \u8868\u4e2d\uff0cid=1 \u7684\u6570\u636e\uff0c\u540d\u5b57\u6539\u4e3a\u66f9\u64cd\uff1b\u628a\u4fee\u6539\u540e\u7684\u6570\u636e\u4e8b\u52a1 Id=101 \u6539\u6210\u5f53\u524d\u4e8b\u52a1\u7248\u672c\u53f7\uff0c\u5e76\u628a roll_pointer \u6307\u5411 undo log \u6570\u636e\u5730\u5740\u3002
              3.\u6700\u65b0\u7684\u5218\u5907\u7684\u8bb0\u5f55\u4e5f\u662f\u540c\u7406\uff0c\u8fdb\u884c\u540c\u6837\u7684\u64cd\u4f5c<\/p>\n\n\n\n

              Read View<\/h3>\n\n\n\n

              Read View \u662f\u4ec0\u4e48\u5462\uff1f\u6709\u4ec0\u4e48\u7528\uff1f<\/h4>\n\n\n\n

              \u5b83\u5c31\u662f\u4e8b\u52a1\u6267\u884c SQL \u8bed\u53e5\u65f6\uff0c\u4ea7\u751f\u7684\u8bfb\u89c6\u56fe\u3002\u5b9e\u9645\u4e0a\u5728 innodb \u4e2d\uff0c\u6bcf\u4e2a SQL \u8bed\u53e5\u6267\u884c\u524d\u90fd\u4f1a\u5f97\u5230\u4e00\u4e2a Read View\u3002\u5b83\u4e3b\u8981\u662f\u7528\u6765\u505a\u53ef\u89c1\u6027\u5224\u65ad\u7684\uff0c\u5373\u5224\u65ad\u5f53\u524d\u4e8b\u52a1\u53ef\u89c1\u54ea\u4e2a\u7248\u672c\u7684\u6570\u636e\u3002<\/p>\n\n\n\n

              Read view \u7684\u51e0\u4e2a\u91cd\u8981\u5c5e\u6027<\/h4>\n\n\n\n
                \n
              • m_ids:\u5f53\u524d\u7cfb\u7edf\u4e2d\u90a3\u4e9b\u6d3b\u8dc3(\u672a\u63d0\u4ea4)\u7684\u8bfb\u5199\u4e8b\u52a1ID, \u5b83\u6570\u636e\u7ed3\u6784\u4e3a\u4e00\u4e2aList\u3002<\/li>\n\n\n\n
              • min_limit_id:\u8868\u793a\u5728\u751f\u6210ReadView\u65f6\uff0c\u5f53\u524d\u7cfb\u7edf\u4e2d\u6d3b\u8dc3\u7684\u8bfb\u5199\u4e8b\u52a1\u4e2d\u6700\u5c0f\u7684\u4e8b\u52a1id\uff0c\u5373m_ids\u4e2d\u7684\u6700\u5c0f\u503c\u3002<\/li>\n\n\n\n
              • max_limit_id:\u8868\u793a\u751f\u6210ReadView\u65f6\uff0c\u7cfb\u7edf\u4e2d\u5e94\u8be5\u5206\u914d\u7ed9\u4e0b\u4e00\u4e2a\u4e8b\u52a1\u7684id\u503c\u3002<\/li>\n\n\n\n
              • creator_trx_id: \u521b\u5efa\u5f53\u524dread view\u7684\u4e8b\u52a1ID<\/li>\n<\/ul>\n\n\n\n

                Read view \u5339\u914d\u6761\u4ef6\u89c4\u5219<\/h4>\n\n\n\n

                1. \u5982\u679c\u6570\u636e\u4e8b\u52a1ID trx_id < min_limit_id\uff0c\u8868\u660e\u751f\u6210\u8be5\u7248\u672c\u7684\u4e8b\u52a1\u5728\u751f\u6210 Read View \u524d\uff0c\u5df2\u7ecf\u63d0\u4ea4(\u56e0\u4e3a\u4e8b\u52a1 ID \u662f\u9012\u589e\u7684)\uff0c\u6240\u4ee5\u8be5\u7248\u672c\u53ef\u4ee5\u88ab\u5f53\u524d\u4e8b\u52a1\u8bbf\u95ee\u3002 <\/p>\n\n\n\n

                2. \u5982\u679ctrx_id>= max_limit_id\uff0c\u8868\u660e\u751f\u6210\u8be5\u7248\u672c\u7684\u4e8b\u52a1\u5728\u751f\u6210 ReadView \u540e\u624d\u751f\u6210\uff0c\u6240\u4ee5\u8be5\u7248\u672c\u4e0d\u53ef\u4ee5\u88ab\u5f53\u524d\u4e8b\u52a1\u8bbf\u95ee\u3002 <\/p>\n\n\n\n

                3. \u5982\u679c min_limit_id =<trx_id< max_limit_id,\u9700\u8170\u5206 3 \u79cd\u60c5\u51b5\u8ba8\u8bba:
                \uff081\uff09\u5982\u679cm_ids\u5305\u542btrx_id,\u5219\u4ee3\u8868 Read View \u751f\u6210\u65f6\u523b\uff0c\u8fd9\u4e2a\u4e8b\u52a1\u8fd8\u672a\u63d0\u4ea4\uff0c\u4f46\u662f\u5982\u679c\u6570\u636e\u7684trx_id\u7b49\u4e8ecreator_trx_id\u7684\u8bdd\uff0c\u8868\u660e\u6570\u636e\u662f\u81ea\u5df1\u751f\u6210\u7684\uff0c\u56e0\u6b64\u662f\u53ef\u89c1\u7684\u3002
                \uff082\uff09\u5982\u679cm_ids\u5305\u542btrx_id\uff0c\u5e76\u4e14trx_id\u4e0d\u7b49\u4e8ecreator_trx_id\uff0c\u5219 Read View \u751f\u6210\u65f6\uff0c\u4e8b\u52a1\u672a\u63d0\u4ea4\uff0c\u5e76\u4e14\u4e0d\u662f\u81ea\u5df1\u751f\u4ea7\u7684\uff0c\u6240\u4ee5\u5f53\u524d\u4e8b\u52a1\u4e5f\u662f\u770b\u4e0d\u89c1\u7684\uff1b
                \uff083\uff09.\u5982\u679cm_ids\u4e0d\u5305\u542btrx_id\uff0c\u5219\u8bf4\u660e\u4f60\u8fd9\u4e2a\u4e8b\u52a1\u5728 Read View \u751f\u6210\u4e4b\u524d\u5c31\u5df2\u7ecf\u63d0\u4ea4\u4e86\uff0c\u4fee\u6539\u7684\u7ed3\u679c\uff0c\u5f53\u524d\u4e8b\u52a1\u662f\u80fd\u770b\u89c1\u7684\u3002<\/p>\n\n\n\n

                MVCC\u5b9e\u73b0\u539f\u7406<\/h2>\n\n\n\n

                \u57fa\u4e8eMVCC\u67e5\u8be2\u7684\u8fc7\u7a0b<\/h3>\n\n\n\n
                  \n
                1. \u83b7\u53d6\u4e8b\u52a1\u81ea\u5df1\u7684\u7248\u672c\u53f7\uff1a\u5728\u6267\u884c\u67e5\u8be2\u4e4b\u524d\uff0c\u6570\u636e\u5e93\u4f1a\u4e3a\u5f53\u524d\u7684\u4e8b\u52a1\u751f\u6210\u4e00\u4e2a\u552f\u4e00\u7684\u4e8b\u52a1 ID\uff0c\u7528\u4e8e\u6807\u8bc6\u8be5\u4e8b\u52a1\u3002\u8fd9\u4e2a\u4e8b\u52a1 ID \u4f1a\u88ab\u7528\u4e8e\u67e5\u8be2\u8fc7\u7a0b\u4e2d\u83b7\u53d6\u5bf9\u5e94\u7684\u5feb\u7167\u65f6\u95f4\u6233\u548c Read View\u3002<\/li>\n\n\n\n
                2. \u83b7\u53d6 Read View\uff1a\u5177\u4f53\u5730\uff0c\u6570\u636e\u5e93\u4f1a\u904d\u5386\u6240\u6709\u6d3b\u8dc3\u7684\u4e8b\u52a1\uff08\u5373\u672a\u63d0\u4ea4\u6216\u8005\u672a\u56de\u6eda\u7684\u4e8b\u52a1\uff09\uff0c\u5c06\u5b83\u4eec\u7684\u4e8b\u52a1\u7248\u672c\u53f7\u52a0\u5165 Read View \u96c6\u5408\u4e2d\uff0c\u5e76\u8bb0\u5f55 Read View \u5bf9\u5e94\u7684\u5feb\u7167\u65f6\u95f4\u6233\u3002<\/li>\n\n\n\n
                3. \u6bd4\u8f83\u7248\u672c\u53f7\uff1a\u5f53\u4e00\u4e2a\u67e5\u8be2\u8bf7\u6c42\u5230\u8fbe\u6570\u636e\u5e93\u65f6\uff0c\u6570\u636e\u5e93\u4f1a\u6309\u7167\u67e5\u8be2\u6761\u4ef6\u67e5\u627e\u7b26\u5408\u6761\u4ef6\u7684\u6570\u636e\uff0c\u5e76\u5c06\u8fd9\u4e9b\u6570\u636e\u7684\u7248\u672c\u53f7\u4e0e\u5f53\u524d\u4e8b\u52a1\u7684 Read View \u4e2d\u7684\u4e8b\u52a1\u7248\u672c\u53f7\u8fdb\u884c\u6bd4\u8f83\u3002\u5982\u679c\u67d0\u4e2a\u6570\u636e\u7248\u672c\u7684\u7248\u672c\u53f7\u6bd4\u5f53\u524d\u4e8b\u52a1\u7684 Read View \u4e2d\u7684\u6700\u5c0f\u4e8b\u52a1\u7248\u672c\u53f7\u8fd8\u8981\u5c0f\uff0c\u90a3\u4e48\u8fd9\u4e2a\u6570\u636e\u7248\u672c\u5bf9\u5f53\u524d\u4e8b\u52a1\u53ef\u89c1\uff0c\u5426\u5219\u8fd9\u4e2a\u6570\u636e\u7248\u672c\u5bf9\u5f53\u524d\u4e8b\u52a1\u4e0d\u53ef\u89c1\u3002<\/li>\n\n\n\n
                4. \u82e5\u4e0d\u7b26\u5408Read View\u53ef\u89c1\u89c4\u5219\uff1a\u90a3\u4e48\u6570\u636e\u5e93\u9700\u8981\u56de\u6eda\u8be5\u6570\u636e\u7248\u672c\u7684\u4fee\u6539\u64cd\u4f5c\uff0c\u5e76\u4e14\u4ece Undo Log \u4e2d\u6062\u590d\u8be5\u6570\u636e\u7248\u672c\u7684\u5386\u53f2\u5feb\u7167\u3002\u8fd9\u4e2a\u5386\u53f2\u5feb\u7167\u662f\u5728\u8be5\u6570\u636e\u7248\u672c\u521b\u5efa\u65f6\uff0c\u5c06\u5f53\u524d\u6570\u636e\u884c\u7684\u526f\u672c\u5199\u5165 Undo Log \u4e2d\u4fdd\u5b58\u7684\u3002<\/li>\n\n\n\n
                5. \u8fd4\u56de\u7b26\u5408\u89c4\u5219\u7684\u6570\u636e\uff1a\u5982\u679c\u4e00\u4e2a\u6570\u636e\u7248\u672c\u5bf9\u5f53\u524d\u4e8b\u52a1\u53ef\u89c1\uff0c\u90a3\u4e48\u6570\u636e\u5e93\u5c31\u76f4\u63a5\u8fd4\u56de\u8be5\u6570\u636e\u7248\u672c\u4e2d\u7684\u6570\u636e\uff0c\u4f5c\u4e3a\u67e5\u8be2\u7ed3\u679c\u3002 <\/li>\n<\/ol>\n\n\n\n

                  \u8bfb\u5df2\u63d0\u4ea4\uff08RC\uff09\u9694\u79bb\u7ea7\u522b\u5206\u6790\uff1a\u5b58\u5728\u4e0d\u53ef\u91cd\u590d\u8bfb\u95ee\u9898<\/h3>\n\n\n\n

                  \u521b\u5efa core_user \u8868\uff0c\u63d2\u5165\u4e00\u6761\u521d\u59cb\u5316\u6570\u636e,\u5982\u4e0b\uff1a<\/p>\n\n\n\n

                  \"\"<\/div><\/figure>\n\n\n\n

                  \u9694\u79bb\u7ea7\u522b\u8bbe\u7f6e\u4e3a\u8bfb\u5df2\u63d0\u4ea4\uff08RC\uff09\uff0c\u4e8b\u52a1 A \u548c\u4e8b\u52a1 B \u540c\u65f6\u5bf9 core_user \u8868\u8fdb\u884c\u67e5\u8be2\u548c\u4fee\u6539\u64cd\u4f5c\u3002<\/p>\n\n\n\n

                  \"\"<\/div><\/figure>\n\n\n\n
                  \"\"<\/div><\/figure>\n\n\n\n

                  \u6700\u540e\u7684\u67e5\u8be2\u7ed3\u679c\u5c06\u4f1a\u662fname = \u201c\u66f9\u64cd\u201d.\u6211\u4eec\u5206\u6790\u4e00\u4e0b\u8be5\u8fc7\u7a0b\uff1a
                  (1) A \u5f00\u542f\u4e8b\u52a1\uff0c\u9996\u5148\u5f97\u5230\u4e00\u4e2a\u4e8b\u52a1 ID \u4e3a 100
                  (2) B \u5f00\u542f\u4e8b\u52a1\uff0c\u5f97\u5230\u4e8b\u52a1 ID \u4e3a 101
                  (3) \u4e8b\u52a1 A \u751f\u6210\u4e00\u4e2a Read View\u3002\u5982\u4e0b\uff1a<\/p>\n\n\n\n

                  \"\"<\/div><\/figure>\n\n\n\n

                  \u56de\u5230\u7248\u672c\u94fe\u4e2d\uff0c\u5f00\u59cb\u4ece\u7248\u672c\u94fe\u4e2d\u6311\u9009\u53ef\u89c1\u7684\u8bb0\u5f55\uff0c\u4ee5\u4e0b\u4e3a\u7248\u672c\u94fe\uff1a<\/p>\n\n\n\n

                  \"\"<\/div><\/figure>\n\n\n\n

                  \u7531\u56fe\u53ef\u4ee5\u770b\u51fa\uff0c\u6700\u65b0\u7248\u672c\u7684\u5217 name \u7684\u5185\u5bb9\u662f\u5b59\u6743\uff0c\u8be5\u7248\u672c\u7684trx_id\u503c\u4e3a 100\u3002\u5f00\u59cb\u6267\u884c read view \u53ef\u89c1\u6027\u89c4\u5219\u6821\u9a8c\uff1a<\/p>\n\n\n\n

                  min_limit_id(100)=<trx_id\uff08100\uff09<102;\ncreator_trx_id = trx_id =100;<\/code><\/pre>\n\n\n\n
                  \u7531\u6b64\u53ef\u5f97\uff0ctrx_id=100 \u7684\u8fd9\u4e2a\u8bb0\u5f55\uff0c\u5f53\u524d\u4e8b\u52a1\u662f\u53ef\u89c1\u7684\u3002\u6240\u4ee5\u67e5\u5230\u662f name \u4e3a\u5b59\u6743\u7684\u8bb0\u5f55\u3002<\/p>\n\n\n\n
                  \uff084) \u4e8b\u52a1 B \u8fdb\u884c\u4fee\u6539\u64cd\u4f5c\uff0c\u628a\u540d\u5b57\u6539\u4e3a\u66f9\u64cd\u3002\u628a\u539f\u6570\u636e\u62f7\u8d1d\u5230 undo log,\u7136\u540e\u5bf9\u6570\u636e\u8fdb\u884c\u4fee\u6539\uff0c\u6807\u8bb0\u4e8b\u52a1 ID \u548c\u4e0a\u4e00\u4e2a\u6570\u636e\u7248\u672c\u5728 undo log \u7684\u5730\u5740\u3002<\/p>\n\n\n\n
                  \"\"<\/div><\/figure>\n\n\n\n
                  (5) \u63d0\u4ea4\u4e8b\u52a1<\/p>\n\n\n\n
                  (6) \u4e8b\u52a1 A \u518d\u6b21\u6267\u884c\u67e5\u8be2\u64cd\u4f5c\uff0c\u65b0\u751f\u6210\u4e00\u4e2a Read View\u3002\u5982\u4e0b\uff1a<\/p>\n\n\n\n
                  \"\"<\/div><\/figure>\n\n\n\n
                  \u7136\u540e\u518d\u6b21\u56de\u5230\u7248\u672c\u94fe\uff0c\u4ece\u7248\u672c\u94fe\u4e2d\u6311\u9009\u53ef\u89c1\u7684\u8bb0\u5f55\u3002\u4ece\u4e0a\u56fe\u53ef\u5f97\uff0c\u6700\u65b0\u7248\u672c\u7684\u5217 name \u7684\u5185\u5bb9\u662f\u66f9\u64cd\uff0c\u8be5\u7248\u672c\u7684trx_id\u503c\u4e3a 101\u3002\u5f00\u59cb\u6267\u884c Read View \u53ef\u89c1\u6027\u89c4\u5219\u6821\u9a8c\uff1a<\/p>\n\n\n\n
                  min_limit_id(100)=<trx_id\uff08101\uff09<max_limit_id\uff08102);<\/code><\/pre>\n\n\n\n
                  \u4f46\u662f,trx_id=101\uff0c\u4e0d\u5c5e\u4e8em_ids\u96c6\u5408\u3002\u56e0\u6b64\uff0ctrx_id=101\u8fd9\u4e2a\u8bb0\u5f55\uff0c\u5bf9\u4e8e\u5f53\u524d\u4e8b\u52a1\u662f\u53ef\u89c1\u7684\u3002\u6240\u4ee5 SQL \u67e5\u8be2\u5230\u7684\u662f name \u4e3a\u66f9\u64cd\u7684\u8bb0\u5f55\u3002
                  \u6839\u636e\u4ee5\u4e0a\u7ed3\u679c\u53ef\u77e5\uff0c\u53d1\u751f\u4e86\u4e0d\u53ef\u91cd\u590d\u8bfb\u3002<\/strong><\/p>\n\n\n\n
                  \u53ef\u91cd\u590d\u8bfb\uff08RR\uff09\u9694\u79bb\u7ea7\u522b\u5206\u6790\uff1a\u89e3\u51b3\u4e0d\u53ef\u91cd\u590d\u8bfb\u95ee\u9898<\/h3>\n\n\n\n
                  \u4e0d\u540c\u9694\u79bb\u7ea7\u522b\u4e0b\uff0cRead View \u7684\u5de5\u4f5c\u65b9\u5f0f\u4e0d\u540c<\/h4>\n\n\n\n
                  \u5b9e\u9645\u4e0a\uff0c\u5404\u79cd\u4e8b\u52a1\u9694\u79bb\u7ea7\u522b\u4e0b\u7684 Read view \u5de5\u4f5c\u65b9\u5f0f\uff0c\u662f\u4e0d\u4e00\u6837\u7684\uff0cRR \u53ef\u4ee5\u89e3\u51b3\u4e0d\u53ef\u91cd\u590d\u8bfb\u95ee\u9898\uff0c\u5c31\u662f\u8ddf Read view \u5de5\u4f5c\u65b9\u5f0f\u6709\u5173\u3002<\/p>\n\n\n\n
                    \n
                  • \u5728\u8bfb\u5df2\u63d0\u4ea4\uff08RC\uff09\u9694\u79bb\u7ea7\u522b\u4e0b\uff0c\u540c\u4e00\u4e2a\u4e8b\u52a1\u91cc\u9762\uff0c\u6bcf\u4e00\u6b21\u67e5\u8be2\u90fd\u4f1a\u4ea7\u751f\u4e00\u4e2a\u65b0\u7684 Read View \u526f\u672c\uff0c\u8fd9\u6837\u5c31\u53ef\u80fd\u9020\u6210\u540c\u4e00\u4e2a\u4e8b\u52a1\u91cc\u524d\u540e\u8bfb\u53d6\u6570\u636e\u53ef\u80fd\u4e0d\u4e00\u81f4\u7684\u95ee\u9898\uff08\u4e0d\u53ef\u91cd\u590d\u8bfb\u5e76\u53d1\u95ee\u9898\uff09\u3002<\/li>\n\n\n\n
                  • \u5728\u53ef\u91cd\u590d\u8bfb\uff08RR\uff09\u9694\u79bb\u7ea7\u522b\u4e0b\uff0c\u4e00\u4e2a\u4e8b\u52a1\u91cc\u53ea\u4f1a\u83b7\u53d6\u4e00\u6b21 read view\uff0c\u90fd\u662f\u526f\u672c\u5171\u7528\u7684\uff0c\u4ece\u800c\u4fdd\u8bc1\u6bcf\u6b21\u67e5\u8be2\u7684\u6570\u636e\u90fd\u662f\u4e00\u6837\u7684\u3002<\/li>\n<\/ul>\n\n\n\n
                    \u5b9e\u4f8b\u5206\u6790<\/h4>\n\n\n\n
                    \u56de\u5230\u521a\u7684\u4f8b\u5b50\uff0c\u5728\u4e8b\u52a1A\u6267\u884c\u7b2c 2 \u4e2a\u67e5\u8be2\u7684\u65f6\u5019\u3002\u590d\u7528\u8001\u7684 Read View \u526f\u672c\uff0c\u7136\u540e\u518d\u6b21\u56de\u5230\u7248\u672c\u94fe\uff0c\u4ece\u7248\u672c\u94fe\u4e2d\u6311\u9009\u53ef\u89c1\u7684\u8bb0\u5f55\uff1a<\/p>\n\n\n\n
                    \"\"<\/div><\/figure>\n\n\n\n
                    \u4ece\u56fe\u53ef\u5f97\uff0c\u6700\u65b0\u7248\u672c\u7684\u5217 name \u7684\u5185\u5bb9\u662f\u66f9\u64cd\uff0c\u8be5\u7248\u672c\u7684trx_id\u503c\u4e3a 101\u3002\u5f00\u59cb\u6267\u884c read view \u53ef\u89c1\u6027\u89c4\u5219\u6821\u9a8c\uff1a<\/p>\n\n\n\n
                    min_limit_id(100)=<trx_id\uff08101\uff09<max_limit_id\uff08102);<\/code><\/pre>\n\n\n\n
                    \u56e0\u4e3am_ids{100,101}\u5305\u542btrx_id\uff08101\uff09\uff0c\u5e76\u4e14creator_trx_id (100) \u4e0d\u7b49\u4e8etrx_id\uff08101\uff09\u3002\u6240\u4ee5\uff0ctrx_id=101\u8fd9\u4e2a\u8bb0\u5f55\uff0c\u5bf9\u4e8e\u5f53\u524d\u4e8b\u52a1\u662f\u4e0d\u53ef\u89c1\u7684\u3002
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