{"id":936,"date":"2025-04-21T20:59:14","date_gmt":"2025-04-21T12:59:14","guid":{"rendered":"https:\/\/eve2333.top\/?p=936"},"modified":"2025-04-21T20:59:23","modified_gmt":"2025-04-21T12:59:23","slug":"mysql%e6%95%b0%e6%8d%ae%e5%ba%93%e5%85%a5%e9%97%a8%e5%88%b0%e5%a4%a7%e8%9b%87%e5%b0%9a%e7%a1%85%e8%b0%b7%e5%ae%8b%e7%ba%a2%e5%ba%b7%e8%80%81%e5%b8%88%e7%ac%94%e8%ae%b0-%e9%ab%98%e7%ba%a7%e7%af%87-p-16","status":"publish","type":"post","link":"https:\/\/eve2333.top\/?p=936","title":{"rendered":"MySQL\u6570\u636e\u5e93\u5165\u95e8\u5230\u5927\u86c7\u5c1a\u7845\u8c37\u5b8b\u7ea2\u5eb7\u8001\u5e08\u7b14\u8bb0 \u9ad8\u7ea7\u7bc7 part16"},"content":{"rendered":"\n

\u7b2c16\u7ae0 \u591a\u7248\u672c\u5e76\u53d1\u63a7\u5236<\/h1>\n\n\n\n

1. \u4ec0\u4e48\u662fMVCC<\/h2>\n\n\n\n

MVCC\uff08Multiversion Concurrency Control\uff09<\/code>\u591a\u7248\u672c\u5e76\u53d1\u63a7\u5236\u3002\u987e\u540d\u601d\u4e49\uff0cMVCC\u662f\u901a\u8fc7\u6570\u636e\u884c\u7684\u591a\u4e2a\u7248\u672c\u7ba1\u7406\u6765\u5b9e\u73b0\u6570\u636e\u5e93\u7684\u5e76\u53d1\u63a7\u5236<\/code>\u3002\u8fd9\u9879\u6280\u672f\u4f7f\u5f97\u5728InnoDB\u7684\u4e8b\u52a1\u9694\u79bb\u7ea7\u522b\u4e0b\u6267\u884c\u4e00\u81f4\u6027\u8bfb<\/code>\u64cd\u4f5c\u6709\u4e86\u4fdd\u8bc1\u3002\u6362\u8a00\u4e4b\uff0c\u5c31\u662f\u4e3a\u4e86\u67e5\u8be2\u4e00\u4e9b\u6b63\u5728\u88ab\u53e6\u4e00\u4e2a\u4e8b\u52a1\u66f4\u65b0\u7684\u884c\uff0c\u5e76\u4e14\u53ef\u4ee5\u770b\u5230\u5b83\u4eec\u88ab\u66f4\u65b0\u4e4b\u524d\u7684\u503c\uff0c\u8fd9\u6837\u5728\u505a\u67e5\u8be2\u7684\u65f6\u5019\u5c31\u4e0d\u7528\u7b49\u5f85\u53e6\u4e00\u4e2a\u4e8b\u52a1\u91ca\u653e\u9501\u3002<\/p>\n\n\n\n

MVCC \u6ca1\u6709\u6b63\u5f0f\u7684\u6807\u51c6\uff0c\u5728\u4e0d\u540c\u7684 DBMS \u4e2d MVCC \u7684\u5b9e\u73b0\u65b9\u5f0f\u53ef\u80fd\u662f\u4e0d\u540c\u7684\uff0c\u4e5f\u4e0d\u662f\u666e\u904d\u4f7f\u7528\u7684\uff08\u5927\u5bb6\u53ef\u4ee5\u53c2\u8003\u76f8\u5173\u7684 DBMS \u6587\u6863\uff09\u3002\u8fd9\u91cc\u8bb2\u89e3InnoDB\u4e2d MVCC \u7684\u5b9e\u73b0\u673a\u5236\uff08MySQL\u5176\u5b83\u7684\u5b58\u50a8\u5f15\u64ce\u5e76\u4e0d\u652f\u6301\u5b83\uff09\u3002<\/p>\n\n\n\n

2. \u5feb\u7167\u8bfb\u4e0e\u5f53\u524d\u8bfb<\/h2>\n\n\n\n

MVCC\u5728MySQL InnoDB\u4e2d\u7684\u5b9e\u73b0\u4e3b\u8981\u662f\u4e3a\u4e86\u63d0\u9ad8\u6570\u636e\u5e93\u5e76\u53d1\u6027\u80fd\uff0c\u7528\u66f4\u597d\u7684\u65b9\u5f0f\u53bb\u5904\u7406\u8bfb-\u5199\u51b2\u7a81<\/code>\uff0c\u505a\u5230\u5373\u4f7f\u6709\u8bfb\u5199\u51b2\u7a81\u65f6\uff0c\u4e5f\u80fd\u505a\u5230\u4e0d\u52a0\u9501<\/code>\uff0c\u975e\u963b\u585e\u5e76\u53d1\u8bfb<\/code>\uff0c\u800c\u8fd9\u4e2a\u8bfb\u6307\u7684\u5c31\u662f\u5feb\u7167\u8bfb<\/code>, \u800c\u975e\u5f53\u524d\u8bfb<\/code>\u3002\u5f53\u524d\u8bfb\u5b9e\u9645\u4e0a\u662f\u4e00\u79cd\u52a0\u9501\u7684\u64cd\u4f5c\uff0c\u662f\u60b2\u89c2\u9501\u7684\u5b9e\u73b0\u3002\u800cMVCC\u672c\u8d28\u662f\u91c7\u7528\u4e50\u89c2\u9501\u601d\u60f3\u7684\u4e00\u79cd\u65b9\u5f0f\u3002<\/p>\n\n\n\n

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

\u5feb\u7167\u8bfb\u53c8\u53eb\u4e00\u81f4\u6027\u8bfb\uff0c\u8bfb\u53d6\u7684\u662f\u5feb\u7167\u6570\u636e\u3002\u4e0d\u52a0\u9501\u7684\u7b80\u5355\u7684SELECT\u90fd\u5c5e\u4e8e\u5feb\u7167\u8bfb<\/strong>\uff0c\u5373\u4e0d\u52a0\u9501\u7684\u975e\u963b\u585e\u8bfb\u3002<\/p>\n\n\n\n

SELECT * FROM player WHERE ...\n<\/code><\/pre>\n\n\n\n
\u4e4b\u6240\u4ee5\u51fa\u73b0\u5feb\u7167\u8bfb\u7684\u60c5\u51b5\uff0c\u662f\u57fa\u4e8e\u63d0\u9ad8\u5e76\u53d1\u6027\u80fd\u7684\u8003\u8651\uff0c\u5feb\u7167\u8bfb\u7684\u5b9e\u73b0\u662f\u57fa\u4e8eMVCC\uff0c\u5b83\u5728\u5f88\u591a\u60c5\u51b5\u4e0b\uff0c\u907f\u514d\u4e86\u52a0\u9501\u64cd\u4f5c\uff0c\u964d\u4f4e\u4e86\u5f00\u9500\u3002<\/p>\n\n\n\n
\u65e2\u7136\u662f\u57fa\u4e8e\u591a\u7248\u672c\uff0c\u90a3\u4e48\u5feb\u7167\u8bfb\u53ef\u80fd\u8bfb\u5230\u7684\u5e76\u4e0d\u4e00\u5b9a\u662f\u6570\u636e\u7684\u6700\u65b0\u7248\u672c\uff0c\u800c\u6709\u53ef\u80fd\u662f\u4e4b\u524d\u7684\u5386\u53f2\u7248\u672c\u3002<\/p>\n\n\n\n
\u5feb\u7167\u8bfb\u7684\u524d\u63d0\u662f\u9694\u79bb\u7ea7\u522b\u4e0d\u662f\u4e32\u884c\u7ea7\u522b\uff0c\u4e32\u884c\u7ea7\u522b\u4e0b\u7684\u5feb\u7167\u8bfb\u4f1a\u9000\u5316\u6210\u5f53\u524d\u8bfb\u3002<\/p>\n\n\n\n
2.2 \u5f53\u524d\u8bfb<\/h3>\n\n\n\n
\u5f53\u524d\u8bfb\u8bfb\u53d6\u7684\u662f\u8bb0\u5f55\u7684\u6700\u65b0\u7248\u672c\uff08\u6700\u65b0\u6570\u636e\uff0c\u800c\u4e0d\u662f\u5386\u53f2\u7248\u672c\u7684\u6570\u636e\uff09\uff0c\u8bfb\u53d6\u65f6\u8fd8\u8981\u4fdd\u8bc1\u5176\u4ed6\u5e76\u53d1\u4e8b\u52a1\u4e0d\u80fd\u4fee\u6539\u5f53\u524d\u8bb0\u5f55\uff0c\u4f1a\u5bf9\u8bfb\u53d6\u7684\u8bb0\u5f55\u8fdb\u884c\u52a0\u9501\u3002\u52a0\u9501\u7684SELECT\uff0c\u6216\u8005\u5bf9\u6570\u636e\u8fdb\u884c\u589e\u5220\u6539\u90fd\u4f1a\u8fdb\u884c\u5f53\u524d\u8bfb\u3002<\/p>\n\n\n\n
SELECT * FROM student LOCK IN SHARE MODE; # \u5171\u4eab\u9501\nSELECT * FROM student FOR UPDATE; # \u6392\u4ed6\u9501\nINSERT INTO student values ... # \u6392\u4ed6\u9501\nDELETE FROM student WHERE ... # \u6392\u4ed6\u9501\nUPDATE student SET ... # \u6392\u4ed6\u9501\n<\/code><\/pre>\n\n\n\n
3. \u590d\u4e60<\/h2>\n\n\n\n
3.1 \u518d\u8c08\u9694\u79bb\u7ea7\u522b<\/h3>\n\n\n\n
\u6211\u4eec\u77e5\u9053\u4e8b\u52a1\u67094\u4e2a\u9694\u79bb\u7ea7\u522b\uff0c\u53ef\u80fd\u5b58\u5728\u4e09\u79cd\u5e76\u53d1\u95ee\u9898<\/p>\n\n\n\n
\"\"<\/figure>\n\n\n\n
\u5728MySQL\u4e2d\uff0c\u9ed8\u8ba4\u7684\u9694\u79bb\u7ea7\u522b\u662f\u53ef\u91cd\u590d\u8bfb\uff0c\u53ef\u4ee5\u89e3\u51b3\u810f\u8bfb\u548c\u4e0d\u53ef\u91cd\u590d\u8bfb\u7684\u95ee\u9898\uff0c\u5982\u679c\u4ec5\u4ece\u5b9a\u4e49\u7684\u89d2\u5ea6\u6765\u770b\uff0c\u5b83\u5e76\u4e0d\u80fd\u89e3\u51b3\u5e7b\u8bfb\u95ee\u9898\u3002\u5982\u679c\u6211\u4eec\u60f3\u8981\u89e3\u51b3\u5e7b\u8bfb\u95ee\u9898\uff0c\u5c31\u9700\u8981\u91c7\u7528\u4e32\u884c\u5316\u7684\u65b9\u5f0f\uff0c\u4e5f\u5c31\u662f\u5c06\u9694\u79bb\u7ea7\u522b\u63d0\u5347\u5230\u6700\u9ad8\uff0c\u4f46\u8fd9\u6837\u4e00\u6765\u5c31\u4f1a\u5927\u5e45\u964d\u4f4e\u6570\u636e\u5e93\u7684\u4e8b\u52a1\u5e76\u53d1\u80fd\u529b\u3002<\/p>\n\n\n\n
MVCC\u53ef\u4ee5\u4e0d\u91c7\u7528\u9501\u673a\u5236\uff0c\u800c\u662f\u901a\u8fc7\u4e50\u89c2\u9501\u7684\u65b9\u5f0f\u6765\u89e3\u51b3\u4e0d\u53ef\u91cd\u590d\u8bfb\u548c\u5e7b\u8bfb\u95ee\u9898!\u5b83\u53ef\u4ee5\u5728\u5927\u591a\u6570\u60c5\u51b5\u4e0b\u66ff\u4ee3\u884c\u7ea7\u9501\uff0c\u964d\u4f4e\u7cfb\u7edf\u7684\u5f00\u9500\u3002<\/p>\n\n\n\n
\"\"<\/figure>\n\n\n\n
\n
\u9488\u5bf9\u5feb\u7167\u8bfb<\/strong>\uff08\u666e\u901a select \u8bed\u53e5\uff09\uff0c\u662f\u901a\u8fc7 MVCC \u65b9\u5f0f\u89e3\u51b3\u4e86\u5e7b\u8bfb<\/strong>\u3002\u56e0\u4e3a\u53ef\u91cd\u590d\u8bfb\u9694\u79bb\u7ea7\u522b\u4e0b\uff0c\u4e8b\u52a1\u6267\u884c\u8fc7\u7a0b\u4e2d\u770b\u5230\u7684\u6570\u636e\uff0c\u4e00\u76f4\u8ddf\u8fd9\u4e2a\u4e8b\u52a1\u542f\u52a8\u65f6\u770b\u5230\u7684\u6570\u636e\u662f\u4e00\u81f4\u7684\uff0c\u5373\u4f7f\u4e2d\u9014\u6709\u5176\u4ed6\u4e8b\u52a1\u63d2\u5165\u4e86\u4e00\u6761\u6570\u636e\uff0c\u67e5\u8be2\u4e0d\u51fa\u6765\u8fd9\u6761\u6570\u636e\u7684\uff0c\u6240\u4ee5\u5c31\u5f88\u597d\u4e86\u907f\u514d\u5e7b\u8bfb\u95ee\u9898\u3002<\/p>\n\n\n\n
\u9488\u5bf9\u5f53\u524d\u8bfb<\/strong>\uff08select \u2026 for update \u7b49\u8bed\u53e5\uff09\uff0c\u662f\u901a\u8fc7 next-key lock\uff08\u8bb0\u5f55\u9501 + \u95f4\u9699\u9501\uff09\u65b9\u5f0f\u89e3\u51b3\u4e86\u5e7b\u8bfb<\/strong>\u3002\u56e0\u4e3a\u5f53\u6267\u884c select \u2026 for update \u8bed\u53e5\u7684\u65f6\u5019\uff0c\u4f1a\u52a0\u4e0a next-key lock\uff0c\u5982\u679c\u6709\u5176\u4ed6\u4e8b\u52a1\u5728 next-key lock \u9501\u8303\u56f4\u5185\u63d2\u5165\u4e86\u4e00\u6761\u8bb0\u5f55\uff0c\u90a3\u4e48\u8fd9\u4e2a\u63d2\u5165\u8bed\u53e5\u5c31\u4f1a\u88ab\u963b\u585e\uff0c\u65e0\u6cd5\u6210\u529f\u63d2\u5165\uff0c\u6240\u4ee5\u5c31\u5f88\u597d\u4e86\u907f\u514d\u5e7b\u8bfb\u95ee\u9898\u3002<\/p>\n<\/blockquote>\n\n\n\n
3.2 \u9690\u85cf\u5b57\u6bb5\u3001Undo Log\u7248\u672c\u94fe<\/h3>\n\n\n\n
\u56de\u987e\u4e00\u4e0bundo\u65e5\u5fd7\u7684\u7248\u672c\u94fe\uff0c\u5bf9\u4e8e\u4f7f\u7528InnoDB<\/code>\u5b58\u50a8\u5f15\u64ce\u7684\u8868\u6765\u8bf4\uff0c\u5b83\u7684\u805a\u7c07\u7d22\u5f15\u8bb0\u5f55\u4e2d\u90fd\u5305\u542b\u4e24\u4e2a\u5fc5\u8981\u7684\u9690\u85cf\u5217\u3002<\/p>\n\n\n\n
    \n
  • trx_id<\/code>\uff1a\u6bcf\u6b21\u4e00\u4e2a\u4e8b\u52a1\u5bf9\u67d0\u6761\u805a\u7c07\u7d22\u5f15\u8bb0\u5f55\u8fdb\u884c\u6539\u52a8\u65f6\uff0c\u90fd\u4f1a\u628a\u8be5\u4e8b\u52a1\u7684\u4e8b\u52a1id<\/code>\u8d4b\u503c\u7ed9trx_id<\/code>\u9690\u85cf\u5217\u3002<\/li>\n\n\n\n
  • roll_pointer<\/code>\uff1a\u6bcf\u6b21\u5bf9\u67d0\u6761\u805a\u7c07\u7d22\u5f15\u8bb0\u5f55\u8fdb\u884c\u6539\u52a8\u65f6\uff0c\u90fd\u4f1a\u628a\u65e7\u7684\u7248\u672c\u5199\u5165\u5230undo\u65e5\u5fd7<\/code>\u4e2d\uff0c\u7136\u540e\u8fd9\u4e2a\u9690\u85cf\u5217\u5c31\u76f8\u5f53\u4e8e\u4e00\u4e2a\u6307\u9488\uff0c\u53ef\u4ee5\u901a\u8fc7\u5b83\u6765\u627e\u5230\u8be5\u8bb0\u5f55\u4fee\u6539\u524d\u7684\u4fe1\u606f\u3002<\/li>\n<\/ul>\n\n\n\n
    \u4e3e\u4f8b\uff1astudent\u8868\u6570\u636e\u5982\u4e0b<\/strong><\/p>\n\n\n\n
    mysql> select *from student;\n+----+--------+--------+\n| id | name   | class  |\n+----+--------+--------+\n|  1 | \u5f20\u4e09   | \u4e00\u73ed    |\n+----+--------+--------+\n<\/code><\/pre>\n\n\n\n
    \u5047\u8bbe\u63d2\u5165\u8be5\u8bb0\u5f55\u7684\u4e8b\u52a1id<\/code>\u4e3a8<\/code>\uff0c\u90a3\u4e48\u6b64\u523b\u8be5\u6761\u8bb0\u5f55\u7684\u793a\u610f\u56fe\u5982\u4e0b\u6240\u793a:<\/p>\n\n\n\n
    \"\"<\/p>\n\n\n\n
    \n
    insert undo \u53ea\u5728\u4e8b\u52a1\u56de\u6eda\u65f6\u8d77\u4f5c\u7528\uff0c\u5f53\u4e8b\u52a1\u63d0\u4ea4\u540e\uff0c\u8be5\u7c7b\u578b\u7684undo\u65e5\u5fd7\u5c31\u6ca1\u7528\u4e86\uff0c\u5b83\u5360\u7528\u7684Undo
    Log Segment\u4e5f\u4f1a\u88ab\u7cfb\u7edf\u56de\u6536\uff08\u4e5f\u5c31\u662f\u8be5undo\u65e5\u5fd7\u5360\u7528\u7684Undo\u9875\u9762\u94fe\u8868\u8981\u4e48\u88ab\u91cd\u7528\uff0c\u8981\u4e48\u88ab\u91ca\u653e\uff09\u3002<\/p>\n<\/blockquote>\n\n\n\n
    \u5047\u8bbe\u4e4b\u540e\u4e24\u4e2a\u4e8b\u52a1id\u5206\u522b\u4e3a10<\/code>\u300120<\/code>\u7684\u4e8b\u52a1\u5bf9\u8fd9\u6761\u8bb0\u5f55\u8fdb\u884cUPDATE<\/code>\u64cd\u4f5c\uff0c\u64cd\u4f5c\u6d41\u7a0b\u5982\u4e0b\uff1a<\/p>\n\n\n\n
    \u53d1\u751f\u65f6\u95f4\u987a\u5e8f<\/th>\u4e8b\u52a110<\/th>\u4e8b\u52a120<\/th><\/tr><\/thead>
    1<\/td>BEGIN;<\/td><\/td><\/tr>
    2<\/td><\/td>BEGIN;<\/td><\/tr>
    3<\/td>UPDATE student SET name=\"\u674e\u56db\" WHERE id=1;<\/td><\/td><\/tr>
    4<\/td>UPDATE student SET name=\"\u738b\u4e94\" WHERE id=1;<\/td><\/td><\/tr>
    5<\/td>COMMIT;<\/td><\/td><\/tr>
    6<\/td><\/td>UPDATE student SET name=\"\u94b1\u4e03\" WHERE id=1;<\/td><\/tr>
    7<\/td><\/td>UPDATE student SET name=\"\u5b8b\u516b\" WHERE id=1;<\/td><\/tr>
    8<\/td><\/td>COMMIT;<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
    \n
    \u80fd\u4e0d\u80fd\u5728\u4e24\u4e2a\u4e8b\u52a1\u4e2d\u4ea4\u53c9\u66f4\u65b0\u540c\u4e00\u6761\u8bb0\u5f55\u5462?\u4e0d\u80fd!\u8fd9\u4e0d\u5c31\u662f\u4e00\u4e2a\u4e8b\u52a1\u4fee\u6539\u4e86\u53e6\u4e00\u4e2a\u672a\u63d0\u4ea4\u4e8b\u52a1\u4fee\u6539\u8fc7\u7684\u6570\u636e\uff0c\u810f\u5199\u3002<\/p>\n\n\n\n
    InnoDB\u4f7f\u7528\u9501\u6765\u4fdd\u8bc1\u4e0d\u4f1a\u6709\u810f\u5199\u60c5\u51b5\u7684\u53d1\u751f\uff0c\u4e5f\u5c31\u662f\u5728\u7b2c\u4e00\u4e2a\u4e8b\u52a1\u66f4\u65b0\u4e86\u67d0\u6761\u8bb0\u5f55\u540e\uff0c\u5c31\u4f1a\u7ed9\u8fd9\u6761\u8bb0\u5f55\u52a0\u9501\uff0c\u53e6\u4e00\u4e2a\u4e8b\u52a1\u518d\u6b21\u66f4\u65b0\u65f6\u5c31\u9700\u8981\u7b49\u5f85\u7b2c\u4e00\u4e2a\u4e8b\u52a1\u63d0\u4ea4\u4e86\uff0c\u628a\u9501\u91ca\u653e\u4e4b\u540e\u624d\u53ef\u4ee5\u7ee7\u7eed\u66f4\u65b0\u3002<\/p>\n<\/blockquote>\n\n\n\n
    \u6bcf\u6b21\u5bf9\u8bb0\u5f55\u8fdb\u884c\u6539\u52a8\uff0c\u90fd\u4f1a\u8bb0\u5f55\u4e00\u6761undo\u65e5\u5fd7\uff0c\u6bcf\u6761undo\u65e5\u5fd7\u4e5f\u90fd\u6709\u4e00\u4e2aroll_pointer<\/code>\u5c5e\u6027\uff08INSERT<\/code>\u64cd\u4f5c\u5bf9\u5e94\u7684undo\u65e5\u5fd7\u6ca1\u6709\u8be5\u5c5e\u6027\uff0c\u56e0\u4e3a\u8be5\u8bb0\u5f55\u5e76\u6ca1\u6709\u66f4\u65e9\u7684\u7248\u672c\uff09\uff0c\u53ef\u4ee5\u5c06\u8fd9\u4e9bundo\u65e5\u5fd7<\/code>\u90fd\u8fde\u8d77\u6765\uff0c\u4e32\u6210\u4e00\u4e2a\u94fe\u8868\uff1a<\/p>\n\n\n\n
    \"\"<\/figure>\n\n\n\n
    \u5bf9\u8be5\u8bb0\u5f55\u6bcf\u6b21\u66f4\u65b0\u540e\uff0c\u90fd\u4f1a\u5c06\u65e7\u503c\u653e\u5230\u4e00\u6761undo\u65e5\u5fd7<\/code>\u4e2d\uff0c\u5c31\u7b97\u662f\u8be5\u8bb0\u5f55\u7684\u4e00\u4e2a\u65e7\u7248\u672c\uff0c\u968f\u7740\u66f4\u65b0\u6b21\u6570\u7684\u589e\u591a\uff0c\u6240\u6709\u7684\u7248\u672c\u90fd\u4f1a\u88abroll_pointer<\/code>\u5c5e\u6027\u8fde\u63a5\u6210\u4e00\u4e2a\u94fe\u8868\uff0c\u6211\u4eec\u628a\u8fd9\u4e2a\u94fe\u8868\u79f0\u4e4b\u4e3a\u7248\u672c\u94fe<\/code>\uff0c\u7248\u672c\u94fe\u7684\u5934\u8282\u70b9\u5c31\u662f\u5f53\u524d\u8bb0\u5f55\u6700\u65b0\u7684\u503c\u3002<\/p>\n\n\n\n
    \u6bcf\u4e2a\u7248\u672c\u4e2d\u8fd8\u5305\u542b\u751f\u6210\u8be5\u7248\u672c\u65f6\u5bf9\u5e94\u7684\u4e8b\u52a1id<\/code>\u3002<\/p>\n\n\n\n
    4. MVCC\u5b9e\u73b0\u539f\u7406\u4e4bReadView<\/h2>\n\n\n\n
    MVCC \u7684\u5b9e\u73b0\u4f9d\u8d56\u4e8e\uff1a\u9690\u85cf\u5b57\u6bb5\u3001Undo Log\u3001Read View<\/strong>\u3002<\/p>\n\n\n\n
    4.1 \u4ec0\u4e48\u662fReadView<\/h3>\n\n\n\n
    \u5728MVCC\u673a\u5236\u4e2d\uff0c\u591a\u4e2a\u4e8b\u52a1\u5bf9\u540c\u4e00\u4e2a\u884c\u8bb0\u5f55\u8fdb\u884c\u66f4\u65b0\u4f1a\u4ea7\u751f\u591a\u4e2a\u5386\u53f2\u5feb\u7167\uff0c\u8fd9\u4e9b\u5386\u53f2\u5feb\u7167\u4fdd\u5b58\u5728Undo Log\u91cc\u3002\u5982\u679c\u4e00\u4e2a\u4e8b\u52a1\u60f3\u8981\u67e5\u8be2\u8fd9\u4e2a\u884c\u8bb0\u5f55\uff0c\u9700\u8981\u8bfb\u53d6\u54ea\u4e2a\u7248\u672c\u7684\u884c\u8bb0\u5f55\u5462?\u8fd9\u65f6\u5c31\u9700\u8981\u7528\u5230ReadView\u4e86\uff0c\u5b83\u5e2e\u6211\u4eec\u89e3\u51b3\u4e86\u884c\u7684\u53ef\u89c1\u6027\u95ee\u9898\u3002<\/p>\n\n\n\n
    ReadView\u5c31\u662f\u4e8b\u52a1\u5728\u4f7f\u7528MVCC\u673a\u5236\u8fdb\u884c\u5feb\u7167\u8bfb\u64cd\u4f5c\u65f6\u4ea7\u751f\u7684\u8bfb\u89c6\u56fe\u3002\u5f53\u4e8b\u52a1\u542f\u52a8\u65f6\uff0c\u4f1a\u751f\u6210\u6570\u636e\u5e93\u7cfb\u7edf\u5f53\u524d\u7684\u4e00\u4e2a\u5feb\u7167\uff0cInnoDB\u4e3a\u6bcf\u4e2a\u4e8b\u52a1\u6784\u9020\u4e86\u4e00\u4e2a\u6570\u7ec4\uff0c\u7528\u6765\u8bb0\u5f55\u5e76\u7ef4\u62a4\u7cfb\u7edf\u5f53\u524d\u6d3b\u8dc3\u4e8b\u52a1<\/code>\u7684ID\uff08\u201c\u6d3b\u8dc3\u201d\u6307\u7684\u5c31\u662f\uff0c\u542f\u52a8\u4e86\u4f46\u8fd8\u6ca1\u63d0\u4ea4\uff09\u3002<\/p>\n\n\n\n
    4.2 \u8bbe\u8ba1\u601d\u8def<\/h3>\n\n\n\n
    \u4f7f\u7528READ UNCOMMITTED<\/code>\u9694\u79bb\u7ea7\u522b\u7684\u4e8b\u52a1\uff0c\u7531\u4e8e\u53ef\u4ee5\u8bfb\u5230\u672a\u63d0\u4ea4\u4e8b\u52a1\u4fee\u6539\u8fc7\u7684\u8bb0\u5f55\uff0c\u6240\u4ee5\u76f4\u63a5\u8bfb\u53d6\u8bb0\u5f55\u7684\u6700\u65b0\u7248\u672c\u5c31\u597d\u4e86\u3002<\/p>\n\n\n\n
    \u4f7f\u7528SERIALIZABLE<\/code>\u9694\u79bb\u7ea7\u522b\u7684\u4e8b\u52a1\uff0cInnoDB\u89c4\u5b9a\u4f7f\u7528\u52a0\u9501\u7684\u65b9\u5f0f\u6765\u8bbf\u95ee\u8bb0\u5f55\u3002<\/p>\n\n\n\n
    \u4f7f\u7528READ COMMITTED<\/code>\u548cREPEATABLE READ<\/code>\u9694\u79bb\u7ea7\u522b\u7684\u4e8b\u52a1\uff0c\u90fd\u5fc5\u987b\u4fdd\u8bc1\u8bfb\u5230\u5df2\u7ecf\u63d0\u4ea4\u4e86\u7684<\/code>\u4e8b\u52a1\u4fee\u6539\u8fc7\u7684\u8bb0\u5f55\u3002\u5047\u5982\u53e6\u4e00\u4e2a\u4e8b\u52a1\u5df2\u7ecf\u4fee\u6539\u4e86\u8bb0\u5f55\u4f46\u662f\u5c1a\u672a\u63d0\u4ea4\uff0c\u662f\u4e0d\u80fd\u76f4\u63a5\u8bfb\u53d6\u6700\u65b0\u7248\u672c\u7684\u8bb0\u5f55\u7684\uff0c\u6838\u5fc3\u95ee\u9898\u5c31\u662f\u9700\u8981\u5224\u65ad\u4e00\u4e0b\u7248\u672c\u94fe\u4e2d\u7684\u54ea\u4e2a\u7248\u672c\u662f\u5f53\u524d\u4e8b\u52a1\u53ef\u89c1\u7684\uff0c\u8fd9\u662fReadView\u8981\u89e3\u51b3\u7684\u4e3b\u8981\u95ee\u9898\u3002<\/p>\n\n\n\n
    \u8fd9\u4e2aReadView\u4e2d\u4e3b\u8981\u5305\u542b4\u4e2a\u6bd4\u8f83\u91cd\u8981\u7684\u5185\u5bb9\uff0c\u5206\u522b\u5982\u4e0b\uff1a<\/p>\n\n\n\n
      \n
    • creator_trx_id<\/code>\uff0c\u521b\u5efa\u8fd9\u4e2a Read View \u7684\u4e8b\u52a1ID\u3002<\/li>\n<\/ul>\n\n\n\n
      \n
      \u8bf4\u660e\uff1a\u53ea\u6709\u5728\u5bf9\u8868\u4e2d\u7684\u8bb0\u5f55\u505a\u6539\u52a8\u65f6\uff08\u6267\u884cINSERT\u3001DELETE\u3001UPDATE\u8fd9\u4e9b\u8bed\u53e5\u65f6\uff09\u624d\u4f1a\u4e3a\u4e8b\u52a1\u5206\u914d\u4e8b\u52a1id\uff0c\u5426\u5219\u5728\u4e00\u4e2a\u53ea\u8bfb\u4e8b\u52a1\u4e2d\u7684\u4e8b\u52a1id\u503c\u90fd\u9ed8\u8ba4\u4e3a0\u3002<\/p>\n<\/blockquote>\n\n\n\n
        \n
      • trx_ids<\/code>\uff0c\u8868\u793a\u5728\u751f\u6210ReadView\u65f6\u5f53\u524d\u7cfb\u7edf\u4e2d\u6d3b\u8dc3\u7684\u8bfb\u5199\u4e8b\u52a1\u7684\u4e8b\u52a1id\u5217\u8868<\/code>\u3002<\/li>\n\n\n\n
      • up_limit_id<\/code>\uff0c\u6d3b\u8dc3\u7684\u4e8b\u52a1\u4e2d\u6700\u5c0f\u7684\u4e8b\u52a1ID\u3002<\/li>\n\n\n\n
      • low_limit_id<\/code>\uff0c\u8868\u793a\u751f\u6210ReadView\u65f6\u7cfb\u7edf\u4e2d\u5e94\u8be5\u5206\u914d\u7ed9\u4e0b\u4e00\u4e2a\u4e8b\u52a1\u7684id<\/code>\u503c\u3002low_limit_id \u662f\u7cfb\u7edf\u6700\u5927\u7684\u4e8b\u52a1id\u503c\uff0c\u8fd9\u91cc\u8981\u6ce8\u610f\u662f\u7cfb\u7edf\u4e2d\u7684\u4e8b\u52a1id\uff0c\u9700\u8981\u533a\u522b\u4e8e\u6b63\u5728\u6d3b\u8dc3\u7684\u4e8b\u52a1ID\u3002<\/li>\n<\/ul>\n\n\n\n
        \n
        \u6ce8\u610f\uff1alow_limit_id\u5e76\u4e0d\u662ftrx_ids\u4e2d\u7684\u6700\u5927\u503c\uff0c\u4e8b\u52a1id\u662f\u9012\u589e\u5206\u914d\u7684\u3002\u6bd4\u5982\uff0c\u73b0\u5728\u6709id\u4e3a1\uff0c2\uff0c3\u8fd9\u4e09\u4e2a\u4e8b\u52a1\uff0c\u4e4b\u540eid\u4e3a3\u7684\u4e8b\u52a1\u63d0\u4ea4\u4e86\u3002\u90a3\u4e48\u4e00\u4e2a\u65b0\u7684\u8bfb\u4e8b\u52a1\u5728\u751f\u6210ReadView\u65f6\uff0ctrx_ids\u5c31\u5305\u62ec1\u548c2\uff0cup_limit_id\u7684\u503c\u5c31\u662f1\uff0clow_limit_id\u7684\u503c\u5c31\u662f4\u3002<\/p>\n<\/blockquote>\n\n\n\n
        \u4e3e\u4f8b:<\/strong><\/p>\n\n\n\n
        trx_ids\u4e3atr2\u3001tr3\u3001tr5\u548ctrx8\u7684\u96c6\u5408\uff0c\u7cfb\u7edf\u7684\u6700\u5927\u4e8b\u52a1ID (low_limit_id)\u4e3atrx8+1(\u5982\u679c\u4e4b\u524d\u6ca1\u6709\u5176\u4ed6\u7684\u65b0\u589e\u4e8b\u52a1)\uff0c\u6d3b\u8dc3\u7684\u6700\u5c0f\u4e8b\u52a1ID (up_limit_id)\u4e3atrx2\u3002<\/p>\n\n\n\n
        \"\"<\/p>\n\n\n\n
        4.3 ReadView\u7684\u89c4\u5219<\/h3>\n\n\n\n
        \u6709\u4e86\u8fd9\u4e2aReadView\uff0c\u8fd9\u6837\u5728\u8bbf\u95ee\u67d0\u6761\u8bb0\u5f55\u65f6\uff0c\u53ea\u9700\u8981\u6309\u7167\u4e0b\u8fb9\u7684\u6b65\u9aa4\u5224\u65ad\u8bb0\u5f55\u7684\u67d0\u4e2a\u7248\u672c\u662f\u5426\u53ef\u89c1\u3002<\/p>\n\n\n\n
          \n
        • \u5982\u679c\u88ab\u8bbf\u95ee\u7248\u672c\u7684trx_id\u5c5e\u6027\u503c\u4e0eReadView\u4e2d\u7684creator_trx_id<\/code>\u503c\u76f8\u540c\uff0c\u610f\u5473\u7740\u5f53\u524d\u4e8b\u52a1\u5728\u8bbf\u95ee\u5b83\u81ea\u5df1\u4fee\u6539\u8fc7\u7684\u8bb0\u5f55\uff0c\u6240\u4ee5\u8be5\u7248\u672c\u53ef\u4ee5\u88ab\u5f53\u524d\u4e8b\u52a1\u8bbf\u95ee\u3002<\/li>\n\n\n\n
        • \u5982\u679c\u88ab\u8bbf\u95ee\u7248\u672c\u7684trx_id\u5c5e\u6027\u503c\u5c0f\u4e8eReadView\u4e2d\u7684up_limit_id<\/code>\u503c\uff0c\u8868\u660e\u751f\u6210\u8be5\u7248\u672c\u7684\u4e8b\u52a1\u5728\u5f53\u524d\u4e8b\u52a1\u751f\u6210ReadView\u524d\u5df2\u7ecf\u63d0\u4ea4\uff0c\u6240\u4ee5\u8be5\u7248\u672c\u53ef\u4ee5\u88ab\u5f53\u524d\u4e8b\u52a1\u8bbf\u95ee\u3002<\/li>\n\n\n\n
        • \u5982\u679c\u88ab\u8bbf\u95ee\u7248\u672c\u7684trx_id\u5c5e\u6027\u503c\u5927\u4e8e\u6216\u7b49\u4e8eReadView\u4e2d\u7684low_limit_id<\/code>\u503c\uff0c\u8868\u660e\u751f\u6210\u8be5\u7248\u672c\u7684\u4e8b\u52a1\u5728\u5f53\u524d\u4e8b\u52a1\u751f\u6210ReadView\u540e\u624d\u5f00\u542f\uff0c\u6240\u4ee5\u8be5\u7248\u672c\u4e0d\u53ef\u4ee5\u88ab\u5f53\u524d\u4e8b\u52a1\u8bbf\u95ee\u3002<\/li>\n\n\n\n
        • \u5982\u679c\u88ab\u8bbf\u95ee\u7248\u672c\u7684trx_id\u5c5e\u6027\u503c\u5728ReadView\u7684up_limit_id<\/code>\u548clow_limit_id<\/code>\u4e4b\u95f4\uff0c\u90a3\u5c31\u9700\u8981\u5224\u65ad\u4e00\u4e0btrx_id\u5c5e\u6027\u503c\u662f\u4e0d\u662f\u5728trx_ids\u5217\u8868\u4e2d\u3002\n
            \n
          • \u5982\u679c\u5728\uff0c\u8bf4\u660e\u521b\u5efaReadView\u65f6\u751f\u6210\u8be5\u7248\u672c\u7684\u4e8b\u52a1\u8fd8\u662f\u6d3b\u8dc3\u7684\uff0c\u8be5\u7248\u672c\u4e0d\u53ef\u4ee5\u88ab\u8bbf\u95ee\u3002<\/li>\n\n\n\n
          • \u5982\u679c\u4e0d\u5728\uff0c\u8bf4\u660e\u521b\u5efaReadView\u65f6\u751f\u6210\u8be5\u7248\u672c\u7684\u4e8b\u52a1\u5df2\u7ecf\u88ab\u63d0\u4ea4\uff0c\u8be5\u7248\u672c\u53ef\u4ee5\u88ab\u8bbf\u95ee\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n
            4.4 MVCC\u6574\u4f53\u64cd\u4f5c\u6d41\u7a0b<\/h3>\n\n\n\n
            \u4e86\u89e3\u4e86\u8fd9\u4e9b\u6982\u5ff5\u4e4b\u540e\uff0c\u6211\u4eec\u6765\u770b\u4e0b\u5f53\u67e5\u8be2\u4e00\u6761\u8bb0\u5f55\u7684\u65f6\u5019\uff0c\u7cfb\u7edf\u5982\u4f55\u901a\u8fc7MVCC\u627e\u5230\u5b83\uff1a<\/p>\n\n\n\n
              \n
            1. \u9996\u5148\u83b7\u53d6\u4e8b\u52a1\u81ea\u5df1\u7684\u7248\u672c\u53f7\uff0c\u4e5f\u5c31\u662f\u4e8b\u52a1ID\uff1b<\/li>\n\n\n\n
            2. \u83b7\u53d6 ReadView\uff1b<\/li>\n\n\n\n
            3. \u67e5\u8be2\u5f97\u5230\u7684\u6570\u636e\uff0c\u7136\u540e\u4e0e ReadView \u4e2d\u7684\u4e8b\u52a1\u7248\u672c\u53f7\u8fdb\u884c\u6bd4\u8f83\uff1b<\/li>\n\n\n\n
            4. \u5982\u679c\u4e0d\u7b26\u5408 ReadView \u89c4\u5219\uff0c\u5c31\u9700\u8981\u4ece Undo Log \u4e2d\u83b7\u53d6\u5386\u53f2\u5feb\u7167\uff1b<\/li>\n\n\n\n
            5. \u6700\u540e\u8fd4\u56de\u7b26\u5408\u89c4\u5219\u7684\u6570\u636e\u3002<\/li>\n<\/ol>\n\n\n\n
              \u5982\u679c\u67d0\u4e2a\u7248\u672c\u7684\u6570\u636e\u5bf9\u5f53\u524d\u4e8b\u52a1\u4e0d\u53ef\u89c1\u7684\u8bdd\uff0c\u90a3\u5c31\u987a\u7740\u7248\u672c\u94fe\u627e\u5230\u4e0b\u4e00\u4e2a\u7248\u672c\u7684\u6570\u636e\uff0c\u7ee7\u7eed\u6309\u7167\u4e0a\u8fb9\u7684\u6b65\u9aa4\u5224\u65ad\u53ef\u89c1\u6027\uff0c\u4f9d\u6b64\u7c7b\u63a8\uff0c\u76f4\u5230\u7248\u672c\u94fe\u4e2d\u7684\u6700\u540e\u4e00\u4e2a\u7248\u672c\u3002\u5982\u679c\u6700\u540e\u4e00\u4e2a\u7248\u672c\u4e5f\u4e0d\u53ef\u89c1\u7684\u8bdd\uff0c\u90a3\u4e48\u5c31\u610f\u5473\u7740\u8be5\u6761\u8bb0\u5f55\u5bf9\u8be5\u4e8b\u52a1\u5b8c\u5168\u4e0d\u53ef\u89c1\uff0c\u67e5\u8be2\u7ed3\u679c\u5c31\u4e0d\u5305\u542b\u8be5\u8bb0\u5f55\u3002<\/p>\n\n\n\n
              \n
              InnoDB\u4e2d\uff0cMVCC\u662f\u901a\u8fc7Undo Log + Read View\u8fdb\u884c\u6570\u636e\u8bfb\u53d6\uff0cUndo Log\u4fdd\u5b58\u4e86\u5386\u53f2\u5feb\u7167\uff0c\u800cRead View\u89c4\u5219\u5e2e\u6211\u4eec\u5224\u65ad\u5f53\u524d\u7248\u672c\u7684\u6570\u636e\u662f\u5426\u53ef\u89c1\u3002<\/p>\n<\/blockquote>\n\n\n\n
              \u5728\u9694\u79bb\u7ea7\u522b\u4e3a\u8bfb\u5df2\u63d0\u4ea4\uff08Read Committed\uff09\u65f6\uff0c\u4e00\u4e2a\u4e8b\u52a1\u4e2d\u7684\u6bcf\u4e00\u6b21 SELECT \u67e5\u8be2\u90fd\u4f1a\u91cd\u65b0\u83b7\u53d6\u4e00\u6b21Read View\u3002<\/p>\n\n\n\n
              \u5982\u8868\u6240\u793a\uff1a<\/p>\n\n\n\n
              \u4e8b\u52a1<\/th>\u8bf4\u660e<\/th><\/tr><\/thead>
              begin;<\/td><\/td><\/tr>
              select * from student where id >2;<\/td>\u83b7\u53d6\u4e00\u6b21Read View<\/td><\/tr>
              .........<\/td><\/td><\/tr>
              select * from student where id >2;<\/td>\u83b7\u53d6\u4e00\u6b21Read View<\/td><\/tr>
              commit;<\/td><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
              \n
              \u6ce8\u610f\uff0c\u6b64\u65f6\u540c\u6837\u7684\u67e5\u8be2\u8bed\u53e5\u90fd\u4f1a\u91cd\u65b0\u83b7\u53d6\u4e00\u6b21 Read View\uff0c\u8fd9\u65f6\u5982\u679c Read View \u4e0d\u540c\uff0c\u5c31\u53ef\u80fd\u4ea7\u751f\u4e0d\u53ef\u91cd\u590d\u8bfb\u6216\u8005\u5e7b\u8bfb\u7684\u60c5\u51b5\u3002<\/p>\n<\/blockquote>\n\n\n\n
              \u5f53\u9694\u79bb\u7ea7\u522b\u4e3a\u53ef\u91cd\u590d\u8bfb\u7684\u65f6\u5019\uff0c\u5c31\u907f\u514d\u4e86\u4e0d\u53ef\u91cd\u590d\u8bfb\uff0c\u8fd9\u662f\u56e0\u4e3a\u4e00\u4e2a\u4e8b\u52a1\u53ea\u5728\u7b2c\u4e00\u6b21SELECT\u7684\u65f6\u5019\u4f1a\u83b7\u53d6\u4e00\u6b21 Read View\uff0c\u800c\u540e\u9762\u6240\u6709\u7684 SELECT \u90fd\u4f1a\u590d\u7528\u8fd9\u4e2a Read View\uff0c\u5982\u4e0b\u8868\u6240\u793a\uff1a<\/p>\n\n\n\n
              \u4e8b\u52a1<\/th>\u8bf4\u660e<\/th><\/tr><\/thead>
              begin;<\/td><\/td><\/tr>
              select * from student where id >2;<\/td>\u53ea\u5728\u7b2c\u4e00\u6b21 SELECT \u7684\u65f6\u5019
              \u83b7\u53d6\u4e00\u6b21Read View<\/td><\/tr>
              .........<\/td><\/td><\/tr>
              select * from student where id >2;<\/td><\/td><\/tr>
              commit;<\/td><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
              5. \u4e3e\u4f8b\u8bf4\u660e<\/h2>\n\n\n\n
              \u5047\u8bbe\u73b0\u5728student\u8868\u4e2d\u53ea\u6709\u4e00\u6761\u7531\u4e8b\u52a1id\u4e3a8\u7684\u4e8b\u52a1\u63d2\u5165\u7684\u4e00\u6761\u8bb0\u5f55:<\/p>\n\n\n\n
              mysql> select *from student;\n+----+--------+--------+\n| id | name   | class  |\n+----+--------+--------+\n|  1 | \u5f20\u4e09   | \u4e00\u73ed    |\n+----+--------+--------+\n<\/code><\/pre>\n\n\n\n
              MVCC\u53ea\u80fd\u5728READ COMMITTED\u548cREPEATABLE READ\u4e24\u4e2a\u9694\u79bb\u7ea7\u522b\u4e0b\u5de5\u4f5c\u3002\u63a5\u4e0b\u6765\u770b\u4e00\u4e0bREAD COMMITTED<\/code>\u548cREPEATABLE READ<\/code>\u6240\u8c13\u7684\u751f\u6210ReadView\u7684\u65f6\u673a\u4e0d\u540c\u5230\u5e95\u4e0d\u540c\u5728\u54ea\u91cc\u3002<\/p>\n\n\n\n
              5.1 READ COMMITTED\u9694\u79bb\u7ea7\u522b\u4e0b<\/h3>\n\n\n\n
              READ COMMITTED<\/strong> \uff1a\u6bcf\u6b21\u8bfb\u53d6\u6570\u636e\u524d\u90fd\u751f\u6210\u4e00\u4e2aReadView<\/strong>\u3002<\/p>\n\n\n\n
              \u73b0\u5728\u6709\u4e24\u4e2a\u4e8b\u52a1id\u5206\u522b\u4e3a10<\/code>\u300120<\/code>\u7684\u4e8b\u52a1\u5728\u6267\u884c\uff1a<\/p>\n\n\n\n
              # Transaction 10\nBEGIN;\nUPDATE student SET name=\"\u674e\u56db\" WHERE id= 1 ;\nUPDATE student SET name=\"\u738b\u4e94\" WHERE id= 1 ;\n\n# Transaction 20\nBEGIN;\n# \u66f4\u65b0\u4e86\u4e00\u4e9b\u522b\u7684\u8868\u7684\u8bb0\u5f55\n...\n<\/code><\/pre>\n\n\n\n
              \n
              \u8bf4\u660e:\u4e8b\u52a1\u6267\u884c\u8fc7\u7a0b\u4e2d\uff0c\u53ea\u6709\u5728\u7b2c\u4e00\u6b21\u771f\u6b63\u4fee\u6539\u8bb0\u5f55\u65f6\uff08\u6bd4\u5982\u4f7f\u7528INSERT\u3001DELETE\u3001UPDATE\u8bed\u53e5)\uff0c\u624d\u4f1a\u88ab\u5206\u914d\u4e00\u4e2a\u5355\u72ec\u7684\u4e8b\u52a1id\uff0c\u8fd9\u4e2a\u4e8b\u52a1id\u662f\u9012\u589e\u7684\u3002\u6240\u4ee5\u6211\u4eec\u624d\u5728\u4e8b\u52a12\u4e2d\u66f4\u65b0\u4e9b\u522b\u7684\u8868\u7684\u8bb0\u5f55\uff0c\u76ee\u7684\u662f\u8ba9\u5b83\u5206
              \u914d\u4e8b\u52a1id\u3002<\/p>\n<\/blockquote>\n\n\n\n
              \u6b64\u523b\uff0c\u8868student \u4e2did\u4e3a1\u7684\u8bb0\u5f55<\/code>\u5f97\u5230\u7684\u7248\u672c\u94fe\u8868\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n\n\n\n
              \"\"<\/figure>\n\n\n\n
              \u5047\u8bbe\u73b0\u5728\u6709\u4e00\u4e2a\u4f7f\u7528READ COMMITTED\u9694\u79bb\u7ea7\u522b\u7684\u4e8b\u52a1\u5f00\u59cb\u6267\u884c\uff1a<\/p>\n\n\n\n
              # \u4f7f\u7528READ COMMITTED\u9694\u79bb\u7ea7\u522b\u7684\u4e8b\u52a1\nBEGIN;\n\n# SELECT1\uff1aTransaction 10\u3001 20 \u672a\u63d0\u4ea4\nSELECT * FROM student WHERE id = 1 ; # \u5f97\u5230\u7684\u5217name\u7684\u503c\u4e3a'\u5f20\u4e09'\n<\/code><\/pre>\n\n\n\n
              \u8fd9\u4e2aSELECT1<\/code>\u7684\u6267\u884c\u8fc7\u7a0b\u5982\u4e0b:<\/p>\n\n\n\n
              \u6b65\u9aa41: \u5728\u6267\u884cSELECT\u8bed\u53e5\u65f6\u4f1a\u5148\u751f\u6210\u4e00\u4e2aReadView<\/code>, ReadView\u7684trx_ids<\/code>\u5217\u8868\u7684\u5185\u5bb9\u5c31\u662f[10\uff0c20]<\/code>\uff0cup_limit_id<\/code>\u4e3a10, low_limit_id<\/code>\u4e3a21, creator_trx_id<\/code>\u4e3a0\u3002<\/p>\n\n\n\n
              \u6b65\u9aa42:\u4ece\u7248\u672c\u94fe\u4e2d\u6311\u9009\u53ef\u89c1\u7684\u8bb0\u5f55\uff0c\u4ece\u56fe\u4e2d\u770b\u51fa\uff0c\u6700\u65b0\u7248\u672c\u7684\u5217name<\/code>\u7684\u5185\u5bb9\u662f'\u738b\u4e94<\/code>'\uff0c\u8be5\u7248\u672c\u7684trx_id<\/code>\u503c\u4e3a10<\/code>\uff0c\u5728trx_ids<\/code>\u5217\u8868\u5185\uff0c\u6240\u4ee5\u4e0d\u7b26\u5408\u53ef\u89c1\u6027\u8981\u6c42\uff0c\u6839\u636eroll_pointer\u8df3\u5230\u4e0b\u4e00\u4e2a\u7248\u672c\u3002<\/p>\n\n\n\n
              \u6b65\u9aa43:\u4e0b\u4e00\u4e2a\u7248\u672c\u7684\u5217name<\/code>\u7684\u5185\u5bb9\u662f'\u674e\u56db<\/code>'\uff0c\u8be5\u7248\u672c\u7684trx_id<\/code>\u503c\u4e5f\u4e3a10<\/code>\uff0c\u4e5f\u5728trx_ids<\/code>\u5217\u8868\u5185\uff0c\u6240\u4ee5\u4e5f\u4e0d\u7b26\u5408\u8981\u6c42\uff0c\u7ee7\u7eed\u8df3\u5230\u4e0b\u4e00\u4e2a\u7248\u672c\u3002<\/p>\n\n\n\n
              \u6b65\u9aa44:\u4e0b\u4e00\u4e2a\u7248\u672c\u7684\u5217name<\/code>\u7684\u5185\u5bb9\u662f'\u5f20\u4e09<\/code>'\uff0c\u8be5\u7248\u672c\u7684trx_id<\/code>\u503c\u4e3a8\uff0c\u5c0f\u4e8eReadView\u4e2d\u7684up_limit_id<\/code>\u503c10<\/code>\uff0c\u6240\u4ee5\u8fd9\u4e2a\u7248\u672c\u662f\u7b26\u5408\u8981\u6c42\u7684\uff0c\u6700\u540e\u8fd4\u56de\u7ed9\u7528\u6237\u7684\u7248\u672c\u5c31\u662f\u8fd9\u6761\u5217name<\/code>\u4e3a\u2018\u5f20\u4e09<\/code>'\u7684\u8bb0\u5f55\u3002<\/p>\n\n\n\n
              \u4e4b\u540e\uff0c\u6211\u4eec\u628a\u4e8b\u52a1id<\/code>\u4e3a 10<\/code> \u7684\u4e8b\u52a1\u63d0\u4ea4\u4e00\u4e0b\uff1a<\/p>\n\n\n\n
              # Transaction 10\nBEGIN;\n\nUPDATE student SET name=\"\u674e\u56db\" WHERE id= 1 ;\nUPDATE student SET name=\"\u738b\u4e94\" WHERE id= 1 ;\n\nCOMMIT;\n<\/code><\/pre>\n\n\n\n
              \u7136\u540e\u518d\u5230\u4e8b\u52a1id\u4e3a 20 \u7684\u4e8b\u52a1\u4e2d\u66f4\u65b0\u4e00\u4e0b\u8868student\u4e2did\u4e3a 1 \u7684\u8bb0\u5f55\uff1a<\/p>\n\n\n\n
              # Transaction 20\nBEGIN;\n\n# \u66f4\u65b0\u4e86\u4e00\u4e9b\u522b\u7684\u8868\u7684\u8bb0\u5f55\n...\nUPDATE student SET name=\"\u94b1\u4e03\" WHERE id= 1 ;\nUPDATE student SET name=\"\u5b8b\u516b\" WHERE id= 1 ;\n<\/code><\/pre>\n\n\n\n
              \u6b64\u523b\uff0c\u8868student\u4e2did\u4e3a 1 \u7684\u8bb0\u5f55\u7684\u7248\u672c\u94fe\u5c31\u957f\u8fd9\u6837\uff1a<\/p>\n\n\n\n
              \"\"<\/figure>\n\n\n\n
              \u7136\u540e\u518d\u5230\u521a\u624d\u4f7f\u7528READ COMMITTED<\/code>\u9694\u79bb\u7ea7\u522b\u7684\u4e8b\u52a1\u4e2d\u7ee7\u7eed\u67e5\u627e\u8fd9\u4e2aid\u4e3a 1 \u7684\u8bb0\u5f55\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n
              # \u4f7f\u7528READ COMMITTED\u9694\u79bb\u7ea7\u522b\u7684\u4e8b\u52a1\nBEGIN;\n\n# SELECT1\uff1aTransaction 10\u3001 20 \u5747\u672a\u63d0\u4ea4\nSELECT * FROM student WHERE id = 1 ; # \u5f97\u5230\u7684\u5217name\u7684\u503c\u4e3a'\u5f20\u4e09'\n\n# SELECT2\uff1aTransaction 10\u63d0\u4ea4\uff0cTransaction 20\u672a\u63d0\u4ea4\nSELECT * FROM student WHERE id = 1 ; # \u5f97\u5230\u7684\u5217name\u7684\u503c\u4e3a'\u738b\u4e94'\n<\/code><\/pre>\n\n\n\n
              \u8fd9\u4e2aSELECT2<\/code>\u7684\u6267\u884c\u8fc7\u7a0b\u5982\u4e0b:<\/p>\n\n\n\n
              \u6b65\u9aa41:\u5728\u6267\u884cSELECT<\/code>\u8bed\u53e5\u65f6\u4f1a\u53c8\u4f1a\u5355\u72ec\u751f\u6210\u4e00\u4e2aReadView<\/code>\uff0c\u8be5ReadView\u7684trx_ids\u5217\u8868\u7684\u5185\u5bb9\u5c31\u662f[20<\/code>],up_limitid<\/code>\u4e3a20,low_limit_id<\/code>\u4e3a21, creator_trx_id<\/code>\u4e3a0<\/code>\u3002<\/p>\n\n\n\n
              \u6b65\u9aa42:\u4ece\u7248\u672c\u94fe\u4e2d\u6311\u9009\u53ef\u89c1\u7684\u8bb0\u5f55\uff0c\u4ece\u56fe\u4e2d\u770b\u51fa\uff0c\u6700\u65b0\u7248\u672c\u7684\u5217name<\/code>\u7684\u5185\u5bb9\u662f\u2018\u5b8b\u516b<\/code>\u2018\uff0c\u8be5\u7248\u672c\u7684trx_id<\/code>\u503c\u4e3a20\uff0c\u5728trx_ids<\/code>\u5217\u8868\u5185\uff0c\u6240\u4ee5\u4e0d\u7b26\u5408\u53ef\u89c1\u6027\u8981\u6c42\uff0c\u6839\u636eroll_pointer<\/code>\u8df3\u5230\u4e0b\u4e00\u4e2a\u7248\u672c\u3002<\/p>\n\n\n\n
              \u6b65\u9aa43:\u4e0b\u4e00\u4e2a\u7248\u672c\u7684\u5217name<\/code>\u7684\u5185\u5bb9\u662f\u2018\u94b1\u4e03<\/code>'\uff0c\u8be5\u7248\u672c\u7684trx_id<\/code>\u503c\u4e3a20<\/code>\uff0c\u4e5f\u5728trx_ids<\/code>\u5217\u8868\u5185\uff0c\u6240\u4ee5\u4e5f\u4e0d\u7b26\u5408\u8981\u6c42\uff0c\u7ee7\u7eed\u8df3\u5230\u4e0b\u4e00\u4e2a\u7248\u672c\u3002<\/p>\n\n\n\n
              \u6b65\u9aa44:\u4e0b\u4e00\u4e2a\u7248\u672c\u7684\u5217name<\/code>\u7684\u5185\u5bb9\u662f'\u738b\u4e94<\/code>'\uff0c\u8be5\u7248\u672c\u7684trx_id<\/code>\u503c\u4e3a10\uff0c\u5c0f\u4e8eReadView<\/code>\u4e2d\u7684up_limit_id<\/code>\u503c20\uff0c\u6240\u4ee5\u8fd9\u4e2a\u7248\u672c\u662f\u7b26\u5408\u8981\u6c42\u7684\uff0c\u6700\u540e\u8fd4\u56de\u7ed9\u7528\u6237\u7684\u7248\u672c\u5c31\u662f\u8fd9\u6761\u5217name<\/code>\u4e3a\u2018\u738b\u4e94<\/code>\u2018\u7684\u8bb0\u5f55\u3002<\/p>\n\n\n\n
              \u4ee5\u6b64\u7c7b\u63a8\uff0c\u5982\u679c\u4e4b\u540e\u4e8b\u52a1id\u4e3a20\u7684\u8bb0\u5f55\u4e5f\u63d0\u4ea4\u4e86\uff0c\u518d\u6b21\u5728\u4f7f\u7528READ COMMITTED\u9694\u79bb\u7ea7\u522b\u7684\u4e8b\u52a1\u4e2d\u67e5\u8be2\u8868student\u4e2did\u503c\u4e3a1\u7684\u8bb0\u5f55\u65f6\uff0c\u5f97\u5230\u7684\u7ed3\u679c\u5c31\u662f\u2018\u5b8b\u516b'\u4e86\uff0c\u5177\u4f53\u6d41\u7a0b\u6211\u4eec\u5c31\u4e0d\u5206\u6790\u4e86\u3002<\/p>\n\n\n\n
              \n
              \u5f3a\u8c03: \u4f7f\u7528READ COMMITTED\u9694\u79bb\u7ea7\u522b\u7684\u4e8b\u52a1\u5728\u6bcf\u6b21\u67e5\u8be2\u5f00\u59cb\u65f6\u90fd\u4f1a\u751f\u6210\u4e00\u4e2a\u72ec\u7acb\u7684ReadView\u3002<\/p>\n<\/blockquote>\n\n\n\n
              5.2 REPEATABLE READ\u9694\u79bb\u7ea7\u522b\u4e0b<\/h3>\n\n\n\n
              \u4f7f\u7528REPEATABLE READ<\/code>\u9694\u79bb\u7ea7\u522b\u7684\u4e8b\u52a1\u6765\u8bf4\uff0c\u53ea\u4f1a\u5728\u7b2c\u4e00\u6b21\u6267\u884c\u67e5\u8be2\u8bed\u53e5\u65f6\u751f\u6210\u4e00\u4e2a ReadView<\/code> \uff0c\u4e4b\u540e\u7684\u67e5\u8be2\u5c31\u4e0d\u4f1a\u91cd\u590d\u751f\u6210\u4e86\u3002<\/p>\n\n\n\n
              \u6bd4\u5982\uff0c\u7cfb\u7edf\u91cc\u6709\u4e24\u4e2a\u4e8b\u52a1id\u5206\u522b\u4e3a 10 \u3001 20 \u7684\u4e8b\u52a1\u5728\u6267\u884c\uff1a<\/p>\n\n\n\n
              # \u5f00\u59cb\u8bb0\u5f55\nmysql> select *from student;\n+----+--------+--------+\n| id | name   | class  |\n+----+--------+--------+\n|  1 | \u5f20\u4e09    | \u4e00\u73ed   |\n+----+--------+--------+\n<\/code><\/pre>\n\n\n\n
              # Transaction 10\nBEGIN;\nUPDATE student SET name=\"\u674e\u56db\" WHERE id= 1 ;\nUPDATE student SET name=\"\u738b\u4e94\" WHERE id= 1 ;\n\n# Transaction 20\nBEGIN;\n# \u66f4\u65b0\u4e86\u4e00\u4e9b\u522b\u7684\u8868\u7684\u8bb0\u5f55\n...\n<\/code><\/pre>\n\n\n\n
              \u6b64\u523b\uff0c\u8868student \u4e2did\u4e3a 1 \u7684\u8bb0\u5f55\u5f97\u5230\u7684\u7248\u672c\u94fe\u8868\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n\n\n\n
              \"\"<\/figure>\n\n\n\n
              \u5047\u8bbe\u73b0\u5728\u6709\u4e00\u4e2a\u4f7f\u7528REPEATABLE READ<\/code>\u9694\u79bb\u7ea7\u522b\u7684\u4e8b\u52a1\u5f00\u59cb\u6267\u884c\uff1a<\/p>\n\n\n\n
              # \u4f7f\u7528REPEATABLE READ\u9694\u79bb\u7ea7\u522b\u7684\u4e8b\u52a1\nBEGIN;\n\n# SELECT1\uff1aTransaction 10\u3001 20 \u672a\u63d0\u4ea4\nSELECT * FROM student WHERE id = 1 ; # \u5f97\u5230\u7684\u5217name\u7684\u503c\u4e3a'\u5f20\u4e09'\n<\/code><\/pre>\n\n\n\n
              \u8fd9\u4e2aSELECT1\u7684\u6267\u884c\u8fc7\u7a0b\u5982\u4e0b\uff08\u7b2c\u4e00\u4e2aReadView\u548c\u8bfb\u5df2\u63d0\u4ea4\u662f\u4e00\u6837\u7684)<\/code>:<\/p>\n\n\n\n
              \u6b65\u9aa41: \u5728\u6267\u884cSELECT\u8bed\u53e5\u65f6\u4f1a\u5148\u751f\u6210\u4e00\u4e2aReadView<\/code> , ReadView\u7684 trx_ids<\/code>\u5217\u8868\u7684\u5185\u5bb9\u5c31\u662f[10\uff0c20]<\/code>\uff0cup_limit_id<\/code>\u4e3a10, low_limit_id<\/code>\u4e3a21, creator_trx_id<\/code>\u4e3a0\u3002<\/p>\n\n\n\n
              \u6b65\u9aa42:\u4ece\u7248\u672c\u94fe\u4e2d\u6311\u9009\u53ef\u89c1\u7684\u8bb0\u5f55\uff0c\u4ece\u56fe\u4e2d\u770b\u51fa\uff0c\u6700\u65b0\u7248\u672c\u7684\u5217name<\/code>\u7684\u5185\u5bb9\u662f'\u738b\u4e94<\/code>'\uff0c\u8be5\u7248\u672c\u7684trx_id<\/code>\u503c\u4e3a10<\/code>\uff0c\u5728trx_ids<\/code>\u5217\u8868\u5185\uff0c\u6240\u4ee5\u4e0d\u7b26\u5408\u53ef\u89c1\u6027\u8981\u6c42\uff0c\u6839\u636eroll_pointer\u8df3\u5230\u4e0b\u4e00\u4e2a\u7248\u672c\u3002<\/p>\n\n\n\n
              \u6b65\u9aa43:\u4e0b\u4e00\u4e2a\u7248\u672c\u7684\u5217name<\/code>\u7684\u5185\u5bb9\u662f'\u674e\u56db<\/code>'\uff0c\u8be5\u7248\u672c\u7684trx_id<\/code>\u503c\u4e5f\u4e3a10<\/code>\uff0c\u4e5f\u5728trx_ids<\/code>\u5217\u8868\u5185\uff0c\u6240\u4ee5\u4e5f\u4e0d\u7b26\u5408\u8981\u6c42\uff0c\u7ee7\u7eed\u8df3\u5230\u4e0b\u4e00\u4e2a\u7248\u672c\u3002<\/p>\n\n\n\n
              \u6b65\u9aa44:\u4e0b\u4e00\u4e2a\u7248\u672c\u7684\u5217name<\/code>\u7684\u5185\u5bb9\u662f'\u5f20\u4e09<\/code>'\uff0c\u8be5\u7248\u672c\u7684trx_id<\/code>\u503c\u4e3a8\uff0c\u5c0f\u4e8eReadView\u4e2d\u7684up_limit_id<\/code>\u503c10<\/code>\uff0c\u6240\u4ee5\u8fd9\u4e2a\u7248\u672c\u662f\u7b26\u5408\u8981\u6c42\u7684\uff0c\u6700\u540e\u8fd4\u56de\u7ed9\u7528\u6237\u7684\u7248\u672c\u5c31\u662f\u8fd9\u6761\u5217name<\/code>\u4e3a\u2018\u5f20\u4e09<\/code>'\u7684\u8bb0\u5f55\u3002<\/p>\n\n\n\n
              \u4e4b\u540e\uff0c\u6211\u4eec\u628a\u4e8b\u52a1id<\/code>\u4e3a10<\/code>\u7684\u4e8b\u52a1\u63d0\u4ea4\u4e00\u4e0b\uff1a<\/p>\n\n\n\n
              # Transaction 10\nBEGIN;\n\nUPDATE student SET name=\"\u674e\u56db\" WHERE id= 1 ;\nUPDATE student SET name=\"\u738b\u4e94\" WHERE id= 1 ;\n\nCOMMIT;\n<\/code><\/pre>\n\n\n\n
              \u7136\u540e\u518d\u5230\u4e8b\u52a1id\u4e3a 20 \u7684\u4e8b\u52a1\u4e2d\u66f4\u65b0\u4e00\u4e0b\u8868student\u4e2did\u4e3a 1 \u7684\u8bb0\u5f55\uff1a<\/p>\n\n\n\n
              # Transaction 20\nBEGIN;\n\n# \u66f4\u65b0\u4e86\u4e00\u4e9b\u522b\u7684\u8868\u7684\u8bb0\u5f55\n...\nUPDATE student SET name=\"\u94b1\u4e03\" WHERE id= 1 ;\nUPDATE student SET name=\"\u5b8b\u516b\" WHERE id= 1 ;\n<\/code><\/pre>\n\n\n\n
              \u6b64\u523b\uff0c\u8868student \u4e2did\u4e3a 1 \u7684\u8bb0\u5f55\u7684\u7248\u672c\u94fe\u957f\u8fd9\u6837\uff1a<\/p>\n\n\n\n
              \"\"<\/figure>\n\n\n\n
              \u7136\u540e\u518d\u5230\u521a\u624d\u4f7f\u7528REPEATABLE READ<\/code>\u9694\u79bb\u7ea7\u522b\u7684\u4e8b\u52a1\u4e2d\u7ee7\u7eed\u67e5\u627e\u8fd9\u4e2aid\u4e3a 1 \u7684\u8bb0\u5f55\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n
              # \u4f7f\u7528REPEATABLE READ\u9694\u79bb\u7ea7\u522b\u7684\u4e8b\u52a1\nBEGIN;\n\n# SELECT1\uff1aTransaction 10\u3001 20 \u5747\u672a\u63d0\u4ea4\nSELECT * FROM student WHERE id = 1 ; # \u5f97\u5230\u7684\u5217name\u7684\u503c\u4e3a'\u5f20\u4e09'\n\n# SELECT2\uff1aTransaction 10\u63d0\u4ea4\uff0cTransaction 20\u672a\u63d0\u4ea4\nSELECT * FROM student WHERE id = 1 ; # \u5f97\u5230\u7684\u5217name\u7684\u503c\u4ecd\u4e3a'\u5f20\u4e09'\n<\/code><\/pre>\n\n\n\n
              \u8fd9\u4e2aSELECT2<\/code>\u7684\u6267\u884c\u8fc7\u7a0b\u5982\u4e0b:<\/p>\n\n\n\n
              \u6b65\u9aa41:\u56e0\u4e3a\u5f53\u524d\u4e8b\u52a1\u7684\u9694\u79bb\u7ea7\u522b\u662fREPEATABLE READ<\/code>\uff0c\u800c\u4e4b\u524d\u5728\u6267\u884cSELECT1<\/code>\u65f6\u5df2\u7ecf\u751f\u6210\u8fc7ReadView\u4e86\uff0c\u6240\u4ee5\u6b64\u65f6\u4f1a\u76f4\u63a5\u590d\u7528\u4e4b\u524d\u7684ReadView<\/code>\uff0c\u4e4b\u524d\u7684ReadView\u7684trx_ids\u5217\u8868\u7684\u5185\u5bb9\u662f[10\uff0c20]\uff0cup_limit_id<\/code>\u4e3a10, low_limit_id<\/code>\u4e3a21, creator_trx_id<\/code>\u4e3a0\u3002<\/p>\n\n\n\n
              \u6b65\u9aa42:\u7136\u540e\u4ece\u7248\u672c\u94fe\u4e2d\u6311\u9009\u53ef\u89c1\u7684\u8bb0\u5f55\uff0c\u4ece\u56fe\u4e2d\u53ef\u4ee5\u770b\u51fa\uff0c\u6700\u65b0\u7248\u672c\u7684\u5217name\u7684\u5185\u5bb9\u662f'\u5b8b\u516b'\uff0c\u8be5\u7248\u672c\u7684trx_id\u503c\u4e3a20\uff0c\u5728trx_ids\u5217\u8868\u5185\uff0c\u6240\u4ee5\u4e0d\u7b26\u5408\u53ef\u89c1\u6027\u8981\u6c42\uff0c\u6839\u636eroll_pointer\u8df3\u5230\u4e0b\u4e00\u4e2a\u7248\u672c\u3002<\/p>\n\n\n\n
              \u6b65\u9aa43:\u4e0b\u4e00\u4e2a\u7248\u672c\u7684\u5217name\u7684\u5185\u5bb9\u662f'\u94b1\u4e03'\uff0c\u8be5\u7248\u672c\u7684trx_id\u503c\u4e3a20\uff0c\u4e5f\u5728trx_ids\u5217\u8868\u5185\uff0c\u6240\u4ee5\u4e5f\u4e0d\u7b26\u5408\u8981\u6c42\uff0c\u7ee7\u7eed\u8df3\u5230\u4e0b\u4e00\u4e2a\u7248\u672c\u3002<\/p>\n\n\n\n
              \u6b65\u9aa44\u2236\u4e0b\u4e00\u4e2a\u7248\u672c\u7684\u5217name\u7684\u5185\u5bb9\u662f'\u738b\u4e94'\uff0c\u8be5\u7248\u672c\u7684trx_id\u503c\u4e3a10\uff0c\u800ctrx_ids\u5217\u8868\u4e2d\u662f\u5305\u542b\u503c\u4e3a10\u7684\u4e8b\u52a1id\u7684\uff0c\u6240\u4ee5\u8be5\u7248\u672c\u4e5f\u4e0d\u7b26\u5408\u8981\u6c42\uff0c\u540c\u7406\u4e0b\u4e00\u4e2a\u5217name\u7684\u5185\u5bb9\u662f'\u674e\u56db\u2019\u7684\u7248\u672c\u4e5f\u4e0d\u7b26\u5408\u8981\u6c42\u3002\u7ee7\u7eed\u8df3\u5230\u4e0b\u4e00\u4e2a\u7248\u672c\u3002<\/p>\n\n\n\n
              \u6b65\u9aa45\u2236\u4e0b\u4e00\u4e2a\u7248\u672c\u7684\u5217name\u7684\u5185\u5bb9\u662f\u2018\u5f20\u4e09'\uff0c\u8be5\u7248\u672c\u7684trx_id\u503c\u4e3a80\uff0c\u5c0f\u4e8eReadView\u4e2d\u7684up_limit_id\u503c10\uff0c\u6240\u4ee5\u8fd9\u4e2a\u7248\u672c\u662f\u7b26\u5408\u8981\u6c42\u7684\uff0c\u6700\u540e\u8fd4\u56de\u7ed9\u7528\u6237\u7684\u7248\u672c\u5c31\u662f\u8fd9\u6761\u5217c\u4e3a'\u5f20\u4e09'\u7684\u8bb0\u5f55\u3002<\/p>\n\n\n\n
              \u4e24\u6b21SELECT\u67e5\u8be2\u5f97\u5230\u7684\u7ed3\u679c\u662f\u91cd\u590d\u7684\uff0c\u8bb0\u5f55\u7684\u5217c\u503c\u90fd\u662f'\u5f20\u4e09'\uff0c\u8fd9\u5c31\u662f\u53ef\u91cd\u590d\u8bfb\u7684\u542b\u4e49\u3002\u5982\u679c\u6211\u4eec\u4e4b\u540e\u518d\u628a\u4e8b\u52a1id\u4e3a20\u7684\u8bb0\u5f55\u63d0\u4ea4\u4e86\uff0c\u7136\u540e\u518d\u5230\u521a\u624d\u4f7f\u7528REPEATABLE READ\u9694\u79bb\u7ea7\u522b\u7684\u4e8b\u52a1\u4e2d\u7ee7\u7eed\u67e5\u627e\u8fd9\u4e2aid\u4e3a1\u7684\u8bb0\u5f55\uff0c\u5f97\u5230\u7684\u7ed3\u679c\u8fd8\u662f\u2018\u5f20\u4e09'\uff0c\u5177\u4f53\u6267\u884c\u8fc7\u7a0b\u5927\u5bb6\u53ef\u4ee5\u81ea\u5df1\u5206\u6790\u4e00\u4e0b\u3002<\/p>\n\n\n\n
              5.3 \u5982\u4f55\u89e3\u51b3\u5e7b\u8bfb<\/h3>\n\n\n\n
              \u63a5\u4e0b\u6765\u8bf4\u660eInnoDB\u662f\u5982\u4f55\u89e3\u51b3\u5e7b\u8bfb\u7684\u3002<\/p>\n\n\n\n
              \u5047\u8bbe\u73b0\u5728\u8868 student \u4e2d\u53ea\u6709\u4e00\u6761\u6570\u636e\uff0c\u6570\u636e\u5185\u5bb9\u4e2d\uff0c\u4e3b\u952e id=1\uff0c\u9690\u85cf\u7684 trx_id=10\uff0c\u5b83\u7684 undo log \u5982\u4e0b\u56fe\u6240\u793a\u3002<\/p>\n\n\n\n
              \"\"<\/p>\n\n\n\n
              \u5047\u8bbe\u73b0\u5728\u6709\u4e8b\u52a1 A \u548c\u4e8b\u52a1 B \u5e76\u53d1\u6267\u884c\uff0c\u4e8b\u52a1 A<\/code>\u7684\u4e8b\u52a1 id \u4e3a20<\/code>\uff0c\u4e8b\u52a1 B<\/code>\u7684\u4e8b\u52a1 id \u4e3a30<\/code>\u3002<\/p>\n\n\n\n
              \u6b65\u9aa41\uff1a\u4e8b\u52a1 A \u5f00\u59cb\u7b2c\u4e00\u6b21\u67e5\u8be2\u6570\u636e\uff0c\u67e5\u8be2\u7684 SQL \u8bed\u53e5\u5982\u4e0b\u3002<\/p>\n\n\n\n
              select * from student where id >= 1;\n<\/code><\/pre>\n\n\n\n
              \u5728\u5f00\u59cb\u67e5\u8be2\u4e4b\u524d\uff0cMySQL \u4f1a\u4e3a\u4e8b\u52a1 A \u4ea7\u751f\u4e00\u4e2a ReadView\uff0c\u6b64\u65f6 ReadView \u7684\u5185\u5bb9\u5982\u4e0b\uff1atrx_ids= [20,30]<\/code>\uff0cup_limit_id=20<\/code>\uff0clow_limit_id=31<\/code>\uff0ccreator_trx_id=20<\/code>\u3002<\/p>\n\n\n\n
              \u7531\u4e8e\u6b64\u65f6\u8868 student \u4e2d\u53ea\u6709\u4e00\u6761\u6570\u636e\uff0c\u4e14\u7b26\u5408 where id>=1 \u6761\u4ef6\uff0c\u56e0\u6b64\u4f1a\u67e5\u8be2\u51fa\u6765\u3002\u7136\u540e\u6839\u636eReadView\u673a\u5236\uff0c\u53d1\u73b0\u8be5\u884c\u6570\u636e\u7684trx_id=10\uff0c\u5c0f\u4e8e\u4e8b\u52a1 A \u7684 ReadView \u91cc up_limit_id\uff0c\u8fd9\u8868\u793a\u8fd9\u6761\u6570\u636e\u662f\u4e8b\u52a1 A \u5f00\u542f\u4e4b\u524d\uff0c\u5176\u4ed6\u4e8b\u52a1\u5c31\u5df2\u7ecf\u63d0\u4ea4\u4e86\u7684\u6570\u636e\uff0c\u56e0\u6b64\u4e8b\u52a1 A \u53ef\u4ee5\u8bfb\u53d6\u5230\u3002<\/p>\n\n\n\n
              \u7ed3\u8bba\uff1a\u4e8b\u52a1 A \u7684\u7b2c\u4e00\u6b21\u67e5\u8be2\uff0c\u80fd\u8bfb\u53d6\u5230\u4e00\u6761\u6570\u636e\uff0cid=1\u3002<\/p>\n\n\n\n
              \u6b65\u9aa42\uff1a\u63a5\u7740\u4e8b\u52a1 B(trx_id=30)\uff0c\u5f80\u8868 student \u4e2d\u65b0\u63d2\u5165\u4e24\u6761\u6570\u636e\uff0c\u5e76\u63d0\u4ea4\u4e8b\u52a1\u3002<\/p>\n\n\n\n
              insert into student(id,name) values(2,'\u674e\u56db'); \ninsert into student(id,name) values(3,'\u738b\u4e94');\n<\/code><\/pre>\n\n\n\n
              \u6b64\u65f6\u8868student \u4e2d\u5c31\u6709\u4e09\u6761\u6570\u636e\u4e86\uff0c\u5bf9\u5e94\u7684 undo \u5982\u4e0b\u56fe\u6240\u793a\uff1a<\/p>\n\n\n\n
              \"\"<\/p>\n\n\n\n
              \u6b65\u9aa43\uff1a\u63a5\u7740\u4e8b\u52a1A \u5f00\u542f\u7b2c\u4e8c\u6b21\u67e5\u8be2\uff0c\u6839\u636e\u53ef\u91cd\u590d\u8bfb\u9694\u79bb\u7ea7\u522b\u7684\u89c4\u5219\uff0c\u6b64\u65f6\u4e8b\u52a1A \u5e76\u4e0d\u4f1a\u518d\u91cd\u65b0\u751f\u6210ReadView\u3002\u6b64\u65f6\u8868 student \u4e2d\u7684 3 \u6761\u6570\u636e\u90fd\u6ee1\u8db3 where id>=1 \u7684\u6761\u4ef6\uff0c\u56e0\u6b64\u4f1a\u5148\u67e5\u51fa\u6765\u3002\u7136\u540e\u6839\u636eReadView \u673a\u5236\uff0c\u5224\u65ad\u6bcf\u6761\u6570\u636e\u662f\u4e0d\u662f\u90fd\u53ef\u4ee5\u88ab\u4e8b\u52a1 A \u770b\u5230\u3002<\/p>\n\n\n\n
              1\uff09\u9996\u5148 id=1 \u7684\u8fd9\u6761\u6570\u636e\uff0c\u524d\u9762\u5df2\u7ecf\u8bf4\u8fc7\u4e86\uff0c\u53ef\u4ee5\u88ab\u4e8b\u52a1 A \u770b\u5230\u3002<\/p>\n\n\n\n
              2\uff09\u7136\u540e\u662f id=2 \u7684\u6570\u636e\uff0c\u5b83\u7684 trx_id=30\uff0c\u6b64\u65f6\u4e8b\u52a1 A \u53d1\u73b0\uff0c\u8fd9\u4e2a\u503c\u5904\u4e8e up_limit_id \u548c low_limit_id \u4e4b\u95f4\uff0c\u56e0\u6b64\u8fd8\u9700\u8981\u518d\u5224\u65ad 30 \u662f\u5426\u5904\u4e8e trx_ids \u6570\u7ec4\u5185\u3002\u7531\u4e8e\u4e8b\u52a1 A \u7684 trx_ids=[20,30]\uff0c\u56e0\u6b64\u5728\u6570\u7ec4\u5185\uff0c\u8fd9\u8868\u793a id=2 \u7684\u8fd9\u6761\u6570\u636e\u662f\u4e0e\u4e8b\u52a1 A \u5728\u540c\u4e00\u65f6\u523b\u542f\u52a8\u7684\u5176\u4ed6\u4e8b\u52a1\u63d0\u4ea4\u7684\uff0c\u6240\u4ee5\u8fd9\u6761\u6570\u636e\u4e0d\u80fd\u8ba9\u4e8b\u52a1 A \u770b\u5230\u3002<\/p>\n\n\n\n
              3\uff09\u540c\u7406\uff0cid=3 \u7684\u8fd9\u6761\u6570\u636e\uff0ctrx_id \u4e5f\u4e3a 30\uff0c\u56e0\u6b64\u4e5f\u4e0d\u80fd\u88ab\u4e8b\u52a1 A \u770b\u89c1\u3002<\/p>\n\n\n\n
              \"\"<\/p>\n\n\n\n
              \u7ed3\u8bba\uff1a\u6700\u7ec8\u4e8b\u52a1 A \u7684\u7b2c\u4e8c\u6b21\u67e5\u8be2\uff0c\u53ea\u80fd\u67e5\u8be2\u51fa id=1 \u7684\u8fd9\u6761\u6570\u636e\u3002\u8fd9\u548c\u4e8b\u52a1 A \u7684\u7b2c\u4e00\u6b21\u67e5\u8be2\u7684\u7ed3\u679c\u662f\u4e00\u6837\u7684\uff0c\u56e0\u6b64\u6ca1\u6709\u51fa\u73b0\u5e7b\u8bfb\u73b0\u8c61\uff0c\u6240\u4ee5\u8bf4\u5728 MySQL \u7684\u53ef\u91cd\u590d\u8bfb\u9694\u79bb\u7ea7\u522b\u4e0b\uff0c\u4e0d\u5b58\u5728\u5e7b\u8bfb\u95ee\u9898\u3002<\/p>\n\n\n\n
              6. \u603b\u7ed3<\/h2>\n\n\n\n
              \u8fd9\u91cc\u4ecb\u7ecd\u4e86MVCC<\/code>\u5728READ COMMITTD<\/code>\u3001REPEATABLE READ<\/code>\u8fd9\u4e24\u79cd\u9694\u79bb\u7ea7\u522b\u7684\u4e8b\u52a1\u5728\u6267\u884c\u5feb\u7167\u8bfb\u64cd\u4f5c\u65f6\u8bbf\u95ee\u8bb0\u5f55\u7684\u7248\u672c\u94fe\u7684\u8fc7\u7a0b\u3002\u8fd9\u6837\u4f7f\u4e0d\u540c\u4e8b\u52a1\u7684\u8bfb-\u5199<\/code>\u3001\u5199-\u8bfb<\/code>\u64cd\u4f5c\u5e76\u53d1\u6267\u884c\uff0c\u4ece\u800c\u63d0\u5347\u7cfb\u7edf\u6027\u80fd\u3002<\/p>\n\n\n\n
              \u6838\u5fc3\u70b9\u5728\u4e8e ReadView \u7684\u539f\u7406\uff0cREAD COMMITTD<\/code>\u3001REPEATABLE READ<\/code>\u8fd9\u4e24\u4e2a\u9694\u79bb\u7ea7\u522b\u7684\u4e00\u4e2a\u5f88\u5927\u4e0d\u540c\u5c31\u662f\u751f\u6210ReadView\u7684\u65f6\u673a\u4e0d\u540c\uff1a<\/p>\n\n\n\n
                \n
              • READ COMMITTD<\/code>\u5728\u6bcf\u4e00\u6b21\u8fdb\u884c\u666e\u901aSELECT\u64cd\u4f5c\u524d\u90fd\u4f1a\u751f\u6210\u4e00\u4e2aReadView<\/li>\n\n\n\n
              • REPEATABLE READ<\/code>\u53ea\u5728\u7b2c\u4e00\u6b21\u8fdb\u884c\u666e\u901aSELECT\u64cd\u4f5c\u524d\u751f\u6210\u4e00\u4e2aReadView\uff0c\u4e4b\u540e\u7684\u67e5\u8be2\u64cd\u4f5c\u90fd\u91cd\u590d\u4f7f\u7528\u8fd9\u4e2aReadView\u3002<\/li>\n<\/ul>\n\n\n\n
                \n
                \u8bf4\u660e: \u6211\u4eec\u4e4b\u524d\u8bf4\u6267\u884cDELETE\u8bed\u53e5\u6216\u8005\u66f4\u65b0\u4e3b\u952e\u7684UPDATE\u8bed\u53e5\u5e76\u4e0d\u4f1a\u7acb\u5373\u628a\u5bf9\u5e94\u7684\u8bb0\u5f55\u5b8c\u5168\u4ece\u9875\u9762\u4e2d\u5220\u9664,\u800c\u662f\u6267\u884c\u4e00\u4e2a\u6240\u8c13\u7684delete mark\u64cd\u4f5c\uff0c\u76f8\u5f53\u4e8e\u53ea\u662f\u5bf9\u8bb0\u5f55\u6253\u4e0a\u4e86\u4e00\u4e2a\u5220\u9664\u6807\u5fd7\u4f4d\uff0c\u8fd9\u4e3b\u8981\u5c31\u662f\u4e3aMVCC\u670d\u52a1\u7684\u3002<\/p>\n<\/blockquote>\n\n\n\n
                \u901a\u8fc7MVCC\u6211\u4eec\u53ef\u4ee5\u89e3\u51b3:<\/p>\n\n\n\n
                  \n
                1. \u8bfb\u5199\u4e4b\u95f4\u963b\u585e\u7684\u95ee\u9898<\/code>\u3002\u901a\u8fc7MVCC\u53ef\u4ee5\u8ba9\u8bfb\u5199\u4e92\u76f8\u4e0d\u963b\u585e\uff0c\u5373\u8bfb\u4e0d\u963b\u585e\u5199\uff0c\u5199\u4e0d\u963b\u585e\u8bfb\uff0c\u8fd9\u6837\u5c31\u53ef\u4ee5\u63d0\u5347\u4e8b
                  \u52a1\u5e76\u53d1\u5904\u7406\u80fd\u529b\u3002<\/li>\n\n\n\n
                2. \u964d\u4f4e\u4e86\u6b7b\u9501\u7684\u6982\u7387<\/code>\u3002\u8fd9\u662f\u56e0\u4e3aMVCC\u91c7\u7528\u4e86\u4e50\u89c2\u9501\u7684\u65b9\u5f0f\uff0c\u8bfb\u53d6\u6570\u636e\u65f6\u5e76\u4e0d\u9700\u8981\u52a0\u9501\uff0c\u5bf9\u4e8e\u5199\u64cd\u4f5c\uff0c\u4e5f\u53ea\u9501
                  \u5b9a\u5fc5\u8981\u7684\u884c\u3002<\/li>\n\n\n\n
                3. \u89e3\u51b3\u5feb\u7167\u8bfb\u7684\u95ee\u9898<\/code>\u3002\u5f53\u6211\u4eec\u67e5\u8be2\u6570\u636e\u5e93\u5728\u67d0\u4e2a\u65f6\u95f4\u70b9\u7684\u5feb\u7167\u65f6\uff0c\u53ea\u80fd\u770b\u5230\u8fd9\u4e2a\u65f6\u95f4\u70b9\u4e4b\u524d\u4e8b\u52a1\u63d0\u4ea4\u66f4\u65b0\u7684\u7ed3
                  \u679c\uff0c\u800c\u4e0d\u80fd\u770b\u5230\u8fd9\u4e2a\u65f6\u95f4\u70b9\u4e4b\u540e\u4e8b\u52a1\u63d0\u4ea4\u7684\u66f4\u65b0\u7ed3\u679c\u3002<\/li>\n<\/ol>\n\n\n\n
                  \u200b<\/p>\n\n\n\n
                  <\/p>\n","protected":false},"excerpt":{"rendered":"
                  \u7b2c16\u7ae0 \u591a\u7248\u672c\u5e76\u53d1\u63a7\u5236 1. \u4ec0\u4e48\u662fMVCC MVCC\uff08Multiversion Concurrency Control\uff09\u591a\u7248\u672c …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"emotion":"","emotion_color":"","title_style":"","license":"","footnotes":""},"categories":[2],"tags":[16],"class_list":["post-936","post","type-post","status-publish","format-standard","hentry","category-2","tag-sql"],"_links":{"self":[{"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/posts\/936","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/eve2333.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=936"}],"version-history":[{"count":1,"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/posts\/936\/revisions"}],"predecessor-version":[{"id":944,"href":"https:\/\/eve2333.top\/index.php?rest_route=\/wp\/v2\/posts\/936\/revisions\/944"}],"wp:attachment":[{"href":"https:\/\/eve2333.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=936"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/eve2333.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=936"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/eve2333.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=936"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}