{"id":519,"date":"2021-07-28T20:35:30","date_gmt":"2021-07-28T12:35:30","guid":{"rendered":"https:\/\/egonlin.com\/?p=519"},"modified":"2025-06-12T15:24:05","modified_gmt":"2025-06-12T07:24:05","slug":"%e6%95%b0%e6%8d%ae%e5%ba%93%e8%af%bb%e7%8e%b0%e8%b1%a1","status":"publish","type":"post","link":"https:\/\/egonlin.com\/?p=519","title":{"rendered":"\u6570\u636e\u5e93\u8bfb\u73b0\u8c61"},"content":{"rendered":"

\u4e00 \u6570\u636e\u5e93\u8bfb\u73b0\u8c61<\/h1>\n

\u6570\u636e\u5e93\u7ba1\u7406\u8f6f\u4ef6\u7684\u201c\u8bfb\u73b0\u8c61\u201d\u6307\u7684\u662f\u5f53\u591a\u4e2a\u4e8b\u52a1\u5e76\u53d1\u6267\u884c\u65f6\uff0c\u5728\u8bfb\u53d6\u6570\u636e\u65b9\u9762\u53ef\u80fd\u78b0\u5230\u7684\u95ee\u9898\uff0c\u5305\u62ec\u6709\u810f\u8bfb\u3001\u4e0d\u53ef\u91cd\u590d\u8bfb\u548c\u5e7b\u8bfb\u3002<\/p>\n

ps\uff1a\u5bf9\u4e8e\u4e00\u4e9b\u6570\u636e\u5e93\u7ba1\u7406\u8f6f\u4ef6\u4f1a\u81ea\u5e26\u76f8\u5e94\u7684\u673a\u5236\u53bb\u89e3\u51b3\u810f\u8bfb\u3001\u4e0d\u53ef\u91cd\u590d\u8bfb\u3001\u5e7b\u8bfb\u7b49\u95ee\u9898\uff0c\u56e0\u4e3a\u8fd9\u4e9b\u81ea\u5e26\u7684\u673a\u5236\uff0c\u4e0b\u8ff0\u7684\u4e00\u4e9b\u5b9e\u9a8c\u73b0\u8c61\u53ef\u80fd\u5728\u67d0\u4e00\u6570\u636e\u5e93\u7ba1\u7406\u8f6f\u4ef6\u7684\u9ed8\u8ba4\u673a\u5236\u4e0b\u5e76\u4e0d\u6210\u7acb\uff0c\u5373\u6211\u4eec\u5e76\u4e0d\u80fd\u5728\u6240\u6709\u6570\u636e\u5e93\u7ba1\u7406\u8f6f\u4ef6\u4e2d\u770b\u5230\u6240\u6709\u7684\u8bfb\u73b0\u8c61\u3002\u6240\u4ee5\u6b64\u5904\u6211\u4eec\u6682\u4e14\u629b\u5f00\u5177\u4f53\u7684\u67d0\u4e2a\u6570\u636e\u5e93\u7ba1\u7406\u8f6f\u4ef6\u7684\u9ed8\u8ba4\u673a\u5236\u7684\u5e72\u6270\uff0c\u6682\u65f6\u5047\u8bbe\u6ca1\u6709\u9644\u52a0\u4efb\u4f55\u673a\u5236\u4e3a\u524d\u63d0\uff0c\u5355\u7eaf\u5730\u53bb\u7406\u89e3\u6570\u636e\u5e93\u7684\u8bfb\u73b0\u8c61\u3002<\/p>\n

<\/a><\/div>\n

1.1\u3001\u810f\u8bfb (dirty read)<\/h2>\n

\u4e8b\u52a1T2\u66f4\u65b0\u4e86\u4e00\u884c\u8bb0\u5f55\u7684\u5185\u5bb9\uff0c\u4f46\u662f\u5e76\u6ca1\u6709\u63d0\u4ea4\u6240\u505a\u7684\u4fee\u6539\u3002<\/p>\n

\u4e8b\u52a1T1\u8bfb\u53d6\u66f4\u65b0\u540e\u7684\u884c\uff0c\u7136\u540eT1\u6267\u884c\u56de\u6eda\u64cd\u4f5c\uff0c\u53d6\u6d88\u4e86\u521a\u624d\u6240\u505a\u7684\u4fee\u6539\u3002\u6b64\u65f6T1\u6240\u8bfb\u53d6\u7684\u884c\u5c31\u65e0\u6548\u4e86\uff0c\u79f0\u4e4b\u4e3a\u810f\u6570\u636e\u3002<\/p>\n

\u4e3e\u4f8b<\/p>\n

\n\n\n\n\n\n\n\n
\u4e8b\u52a1\u4e00<\/th>\n\u4e8b\u52a1\u4e8c<\/th>\n<\/tr>\n
\/* Query 1 *\/<\/code>
\n
\nSELECT age FROM users WHERE id = 1;
\n<\/code>
\n\/* will read 20 *\/<\/code><\/td>\n		<\/td>\n<\/tr>\n
<\/td>\n
\n\/* Query 2 *\/<\/code>
\nUPDATE users SET age = 21 WHERE id = 1;<\/code>
\n
\n\/* No commit here *\/<\/code><\/td>\n<\/tr>\n

\n\/* Query 1 *\/<\/code>
\nSELECT age FROM users WHERE id = 1;<\/code>
\n\/* will read 21 *\/<\/code><\/td>\n		<\/td>\n<\/tr>\n
<\/td>\n
\nROLLBACK;<\/code>
\n\/* lock-based DIRTY READ *\/<\/code><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u4e8b\u52a12\u56de\u6eda\u540e\u5c31\u6ca1\u6709id\u662f1\uff0cage\u662f21\u7684\u6570\u636e\u4e86\u3002\u6240\u4ee5\uff0c\u4e8b\u52a1\u4e00\u8bfb\u5230\u4e86\u4e00\u6761\u810f\u6570\u636e\u3002<\/p>\n

<\/a><\/div>\n

1.2\u3001\u4e0d\u53ef\u91cd\u590d\u8bfb\u53d6 (nonrepeatable read)<\/h2>\n

\u4e8b\u52a1T1\u8bfb\u53d6\u4e00\u884c\u8bb0\u5f55\uff0c\u7d27\u63a5\u7740\u4e8b\u52a1T2\u4fee\u6539\u4e86T1\u521a\u624d\u8bfb\u53d6\u7684\u90a3\u4e00\u884c\u8bb0\u5f55\u5e76\u4e14\u63d0\u4ea4\u4e86\u3002<\/p>\n

\u7136\u540eT1\u53c8\u518d\u6b21\u8bfb\u53d6\u8fd9\u884c\u8bb0\u5f55\uff0c\u53d1\u73b0\u4e0e\u521a\u624d\u8bfb\u53d6\u7684\u7ed3\u679c\u4e0d\u540c\u3002\u8fd9\u5c31\u79f0\u4e3a\u201c\u4e0d\u53ef\u91cd\u590d\u201d\u8bfb\uff0c\u56e0\u4e3aT1\u539f\u6765\u8bfb\u53d6\u7684\u90a3\u884c\u8bb0\u5f55\u5df2\u7ecf\u53d1\u751f\u4e86\u53d8\u5316\u3002<\/p>\n

\u4e3e\u4f8b<\/p>\n

\u5728\u57fa\u4e8e\u9501\u7684\u5e76\u53d1\u63a7\u5236\u4e2d\u201c\u4e0d\u53ef\u91cd\u590d\u8bfb(non-repeatable read)\u201d\u73b0\u8c61\u53d1\u751f\u5728\u5f53\u6267\u884cSELECT \u64cd\u4f5c\u65f6\u6ca1\u6709\u83b7\u5f97\u8bfb\u9501(read locks)\u6216\u8005SELECT\u64cd\u4f5c\u6267\u884c\u5b8c\u540e\u9a6c\u4e0a\u91ca\u653e\u4e86\u8bfb\u9501\uff1b \u591a\u7248\u672c\u5e76\u53d1\u63a7\u5236\u4e2d\u5f53\u6ca1\u6709\u8981\u6c42\u4e00\u4e2a\u63d0\u4ea4\u51b2\u7a81\u7684\u4e8b\u52a1\u56de\u6eda\u4e5f\u4f1a\u53d1\u751f\u201c\u4e0d\u53ef\u91cd\u590d\u8bfb(non-repeatable read)\u201d\u73b0\u8c61\u3002<\/p>\n

\n\n\n\n\n\n\n
\u4e8b\u52a1\u4e00<\/th>\n\u4e8b\u52a1\u4e8c<\/th>\n<\/tr>\n
\/* Query 1 *\/<\/code>
\n
\nSELECT * FROM users WHERE id = 1;
\n<\/code><\/td>\n		<\/td>\n<\/tr>\n
<\/td>\n
\n\/* Query 2 *\/<\/code>
\nUPDATE users SET age = 21 WHERE id = 1;<\/code>
\n
\nCOMMIT;<\/code>
\n
\n\/* in multiversion concurrency
\ncontrol, or lock-based READ COMMITTED *\/
\n<\/code><\/td>\n<\/tr>\n

\n\/* Query 1 *\/<\/code>
\nSELECT * FROM users WHERE id = 1;<\/code>
\n
\nCOMMIT;<\/code>
\n\/*lock-based REPEATABLE READ *\/<\/code><\/td>\n		<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u4e8b\u52a12\u63d0\u4ea4\u6210\u529f\uff0c\u56e0\u6b64\u4ed6\u5bf9id\u4e3a1\u7684\u884c\u7684\u4fee\u6539\u5c31\u5bf9\u5176\u4ed6\u4e8b\u52a1\u53ef\u89c1\u4e86\u3002\u4f46\u662f\u4e8b\u52a11\u5728\u6b64\u524d\u5df2\u7ecf\u4ece\u8fd9\u884c\u8bfb\u5230\u4e86\u53e6\u5916\u4e00\u4e2a\u201cage\u201d\u7684\u503c\u3002<\/p>\n

<\/a><\/div>\n

1.3\u3001\u5e7b\u50cf\u8bfb\u53d6 (phantom read)<\/h2>\n
\n

\u5e7b\u8bfb(phantom read)\u201d\u662f\u4e0d\u53ef\u91cd\u590d\u8bfb(Non-repeatable reads)\u7684\u4e00\u79cd\u7279\u6b8a\u573a\u666f:
\n\u5f53\u4e8b\u52a1\u6ca1\u6709\u83b7\u53d6\u8303\u56f4\u9501\u7684\u60c5\u51b5\u4e0b\u6267\u884cSELECT \u2026 WHERE\u64cd\u4f5c\u6709\u53ef\u80fd\u4f1a\u53d1\u751f\u201c\u5e7b\u5f71\u8bfb(phantom read)\u201d\u3002<\/p>\n<\/div>\n

\u4e8b\u52a1T1\u8bfb\u53d6\u6216\u4fee\u6539\u4e86\u6307\u5b9a\u7684WHERE\u5b50\u53e5\u6240\u8fd4\u56de\u7684\u7ed3\u679c\u96c6\u3002<\/p>\n

\u7136\u540e\u4e8b\u52a1T2\u65b0\u63d2\u5165\u4e00\u884c\u8bb0\u5f55\uff0c\u8fd9\u884c\u8bb0\u5f55\u6070\u597d\u53ef\u4ee5\u6ee1\u8db3T1\u6240\u4f7f\u7528\u7684\u67e5\u8be2\u6761\u4ef6\u4e2d\u7684WHERE \u5b50\u53e5\u7684\u6761\u4ef6\u3002<\/p>\n

\u7136\u540eT1\u53c8\u4f7f\u7528\u76f8\u540c\u7684\u67e5\u8be2\u518d\u6b21\u5bf9\u8868\u8fdb\u884c\u68c0\u7d22\uff0c\u4f46\u662f\u6b64\u65f6\u5374\u770b\u5230\u4e86\u4e8b\u52a1T2\u521a\u624d\u63d2\u5165\u7684\u65b0\u884c\u6216\u8005\u53d1\u73b0\u4e86\u5904\u4e8eWHRE\u5b50\u53e5\u8303\u56f4\u5185\uff0c\u4f46\u5374\u672a\u66fe\u4fee\u6539\u8fc7\u7684\u8bb0\u5f55\u3002\u5c31\u597d\u50cf\u201c\u5e7b\u89c9\u201d\u4e00\u6837\uff0c\u56e0\u4e3a\u5bf9T1\u6765\u8bf4\u8fd9\u4e00\u884c\u5c31\u50cf\u7a81\u7136\u51fa\u73b0\u7684\u4e00\u6837\u3002<\/p>\n

\u4e00\u822c\u89e3\u51b3\u5e7b\u8bfb\u7684\u65b9\u6cd5\u662f\u589e\u52a0\u8303\u56f4\u9501RangeS\uff0c\u9501\u5b9a\u68c0\u9501\u8303\u56f4\u4e3a\u53ea\u8bfb\uff0c\u8fd9\u6837\u5c31\u907f\u514d\u4e86\u5e7b\u8bfb\u3002<\/p>\n

\u4e3e\u4f8b<\/p>\n

\u5f53\u4e8b\u52a11\u4e24\u6b21\u6267\u884cSELECT \u2026 WHERE\u68c0\u7d22\u4e00\u5b9a\u8303\u56f4\u5185\u6570\u636e\u7684\u64cd\u4f5c\u4e2d\u95f4\uff0c\u4e8b\u52a12\u5728\u8fd9\u4e2a\u8868\u4e2d\u521b\u5efa\u4e86(\u5982INSERT)\u4e86\u4e00\u884c\u65b0\u6570\u636e\uff0c\u8fd9\u6761\u65b0\u6570\u636e\u6b63\u597d\u6ee1\u8db3\u4e8b\u52a11\u7684\u201cWHERE\u201d\u5b50\u53e5\u3002<\/p>\n

\n\n\n\n\n\n\n
\u4e8b\u52a1\u4e00<\/th>\n\u4e8b\u52a1\u4e8c<\/th>\n<\/tr>\n
\/* Query 1 *\/<\/code>
\n
\nSELECT * FROM users
\nWHERE age BETWEEN 10 AND 30;
\n<\/code><\/td>\n		<\/td>\n<\/tr>\n
<\/td>\n
\n\/* Query 2 *\/<\/code>
\nINSERT INTO users VALUES ( 3, 'Bob', 27 );<\/code>
\n
\nCOMMIT;<\/code><\/td>\n<\/tr>\n

\n\/* Query 1 *\/<\/code>
\nSELECT * FROM users
\nWHERE age BETWEEN 10 AND 30;<\/code><\/td>\n		<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u4e8b\u52a1\u4e00\u6267\u884c\u4e86\u4e24\u6b21\u76f8\u540c\u7684\u67e5\u8be2\u64cd\u4f5c\u3002\u4f46\u662f\u4e24\u6b21\u64cd\u4f5c\u4e2d\u95f4\u4e8b\u52a1\u4e8c\u5411\u6570\u636e\u5e93\u4e2d\u589e\u52a0\u4e86\u4e00\u6761\u7b26\u5408\u4e8b\u52a1\u4e00\u7684\u67e5\u8be2\u6761\u4ef6\u7684\u6570\u636e\uff0c\u5bfc\u81f4\u5e7b\u8bfb\u3002<\/p>\n

<\/a><\/div>\n

\u4e8c \u89e3\u51b3\u65b9\u6848<\/h1>\n

\u5176\u5b9e\uff0c\u810f\u5199\u3001\u810f\u8bfb\u3001\u4e0d\u53ef\u91cd\u590d\u8bfb\u3001\u5e7b\u8bfb\uff0c\u90fd\u662f\u56e0\u4e3a\u4e1a\u52a1\u7cfb\u7edf\u4f1a\u591a\u7ebf\u7a0b\u5e76\u53d1\u6267\u884c\uff0c\u6bcf\u4e2a\u7ebf\u7a0b\u53ef\u80fd\u90fd\u4f1a\u5f00\u542f\u4e00\u4e2a\u4e8b\u52a1\uff0c\u6bcf\u4e2a\u4e8b\u52a1\u90fd\u4f1a\u6267\u884c\u589e\u5220\u6539\u67e5\u64cd\u4f5c\u3002\u7136\u540e\u6570\u636e\u5e93\u4f1a\u5e76\u53d1\u6267\u884c\u591a\u4e2a\u4e8b\u52a1\uff0c\u591a\u4e2a\u4e8b\u52a1\u53ef\u80fd\u4f1a\u5e76\u53d1\u5730\u5bf9\u7f13\u5b58\u9875\u91cc\u7684\u540c\u4e00\u6279\u6570\u636e\u8fdb\u884c\u589e\u5220\u6539\u67e5\u64cd\u4f5c\uff0c\u4e8e\u662f\u8fd9\u4e2a\u5e76\u53d1\u589e\u5220\u6539\u67e5\u540c\u4e00\u6279\u6570\u636e\u7684\u95ee\u9898\uff0c\u53ef\u80fd\u5c31\u4f1a\u5bfc\u81f4\u6211\u4eec\u8bf4\u7684\u810f\u5199\u3001\u810f\u8bfb\u3001\u4e0d\u53ef\u91cd\u590d\u8bfb\u3001\u5e7b\u8bfb\u8fd9\u4e9b\u95ee\u9898\u3002<\/p>\n

\u6240\u4ee5\u8fd9\u4e9b\u95ee\u9898\u7684\u672c\u8d28\uff0c\u90fd\u662f\u6570\u636e\u5e93\u7684\u591a\u4e8b\u52a1\u5e76\u53d1\u95ee\u9898\uff0c\u90a3\u4e48\u4e3a\u4e86\u89e3\u51b3\u591a\u4e8b\u52a1\u5e76\u53d1\u5e26\u6765\u7684\u810f\u8bfb\u3001\u4e0d\u53ef\u91cd\u590d\u8bfb\u3001\u5e7b\u8bfb\u7b49\u8bfb\u7b49\u95ee\u9898\uff0c\u6570\u636e\u5e93\u624d\u8bbe\u8ba1\u4e86\u9501\u673a\u5236<\/a>\u3001\u4e8b\u52a1\u9694\u79bb\u673a\u5236<\/a>\u3001MVCC \u591a\u7248\u672c\u9694\u79bb\u673a\u5236\uff0c\u7528\u4e00\u6574\u5957\u673a\u5236\u6765\u89e3\u51b3\u591a\u4e8b\u52a1\u5e76\u53d1\u95ee\u9898\uff0c\u4e0b\u9762\u6211\u4eec\u6765\u5206\u522b\u4ecb\u7ecd\u4e00\u4e0b\u5b83\u4eec<\/p>\n","protected":false},"excerpt":{"rendered":"

\u4e00 \u6570\u636e\u5e93\u8bfb\u73b0\u8c61 \u6570\u636e\u5e93\u7ba1\u7406\u8f6f\u4ef6\u7684\u201c\u8bfb\u73b0\u8c61\u201d\u6307\u7684\u662f\u5f53\u591a\u4e2a\u4e8b\u52a1\u5e76\u53d1\u6267\u884c\u65f6\uff0c\u5728\u8bfb\u53d6\u6570\u636e\u65b9\u9762\u53ef\u80fd\u78b0\u5230\u7684\u95ee\u9898\uff0c\u5305\u62ec\u6709\u810f […]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[86],"tags":[21,19,99,22,100,20],"_links":{"self":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts\/519"}],"collection":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=519"}],"version-history":[{"count":1,"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts\/519\/revisions"}],"predecessor-version":[{"id":11507,"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts\/519\/revisions\/11507"}],"wp:attachment":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=519"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=519"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=519"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}