{"id":1779,"date":"2019-01-22T23:26:42","date_gmt":"2019-01-22T15:26:42","guid":{"rendered":"https:\/\/coderbee.net\/?p=1779"},"modified":"2019-04-05T18:34:12","modified_gmt":"2019-04-05T10:34:12","slug":"%e3%80%8amysql-%e5%ae%9e%e6%88%9845%e8%ae%b2%e3%80%8b-%e7%ac%94%e8%ae%b0-%e9%94%81","status":"publish","type":"post","link":"https:\/\/coderbee.net\/index.php\/db\/20190122\/1779","title":{"rendered":"\u300aMySQL \u5b9e\u621845\u8bb2\u300b&#8211;\u7b14\u8bb0&#8211;\u9501"},"content":{"rendered":"<h1>\u9501<\/h1>\n<p>\u6839\u636e\u52a0\u9501\u7684\u8303\u56f4\uff0cMySQL \u91cc\u9762\u7684\u9501\u5927\u81f4\u53ef\u4ee5\u5206\u6210\u5168\u5c40\u9501\u3001\u8868\u7ea7\u9501\u548c\u884c\u9501\u4e09\u7c7b\u3002<\/p>\n<h2>\u5168\u5c40\u9501<\/h2>\n<p>\u5168\u5c40\u9501\u662f\u5bf9\u6574\u4e2a\u6570\u636e\u5e93\u5b9e\u4f8b\u52a0\u9501\u3002MySQL \u63d0\u4f9b\u7684\u4e00\u4e2a\u52a0\u5168\u5c40\u9501\u7684\u547d\u4ee4\uff1a <code>Flush tables with read lock<\/code> (FTWRL)\uff0c\u8ba9\u6574\u4e2a\u5e93\u5904\u4e8e\u53ea\u8bfb\u72b6\u6001\u3002<\/p>\n<p>\u5168\u5c40\u9501\u7684\u5178\u578b\u4f7f\u7528\u573a\u666f\u662f\u505a\u5168\u5e93\u903b\u8f91\u5907\u4efd\u3002<\/p>\n<p>\u903b\u8f91\u5907\u4efd\u5de5\u5177 mysqldump \u4f7f\u7528\u53c2\u6570 -single-transaction \u7684\u65f6\u5019\u5728\u5bfc\u6570\u636e\u4e4b\u524d\u5c31\u4f1a\u542f\u52a8\u4e00\u4e2a\u4e8b\u52a1\uff0c\u6765\u786e\u4fdd\u62ff\u5230\u4e00\u81f4\u6027\u89c6\u56fe\u3002<\/p>\n<p>\u4e00\u81f4\u6027\u8bfb\u7684\u524d\u63d0\u662f\u5f15\u64ce\u8981\u652f\u6301\u8fd9\u4e2a\u9694\u79bb\u7ea7\u522b\u7684\u4e8b\u52a1\u3002<\/p>\n<p><code>set global readonly=true<\/code> \u4e5f\u53ef\u4ee5\u8ba9\u5168\u5e93\u8fdb\u5165\u53ea\u8bfb\u72b6\u6001\u3002\u4f46\u5b58\u5728\u4e24\u4e2a\u98ce\u9669\uff1a readonly \u7684\u503c\u53ef\u80fd\u88ab\u7528\u6765\u505a\u5176\u4ed6\u903b\u8f91\uff0c\u6bd4\u5982\u5224\u7b49\u4e00\u4e2a\u5e93\u662f\u4e3b\u5e93\u8fd8\u662f\u5907\u5e93\uff1b\u8bbe\u7f6e readonly \u4e4b\u540e\uff0c\u5982\u679c\u5ba2\u6237\u7aef\u53d1\u751f\u5f02\u5e38\uff0c\u5219\u6570\u636e\u5e93\u4f1a\u4e00\u76f4\u4fdd\u6301 readonly \u72b6\u6001\u3002<\/p>\n<p>\u5728 slave \u4e0a\uff0c\u5982\u679c\u7528\u6237\u6709\u8d85\u7ea7\u6743\u9650\u7684\u8bdd\uff0c\u5168\u5e93\u53ea\u8bfb <code>readonly=true<\/code> \u662f\u5931\u6548\u7684\u3002<\/p>\n<p>FTWRL \u6267\u884c\u5b8c\u540e\u5982\u679c\u5ba2\u6237\u7aef\u5f02\u5e38\u65ad\u5f00\uff0cMySQL \u4f1a\u81ea\u52a8\u91ca\u653e\u8fd9\u4e2a\u5168\u5c40\u9501\uff0c\u6574\u4e2a\u5e93\u56de\u5230\u53ef\u4ee5\u6b63\u5e38\u66f4\u65b0\u7684\u72b6\u6001\u3002<\/p>\n<p><!--more--><\/p>\n<h2>\u8868\u7ea7\u9501<\/h2>\n<p>MySQL \u8868\u7ea7\u9501\u6709\u4e24\u79cd\uff1a\u8868\u9501\u548c\u5143\u6570\u636e\u9501\uff08meta data lock, MDL\uff09\u3002<\/p>\n<p>\u8868\u9501\u7684\u8bed\u6cd5\u662f\uff1a <code>lock tables t1 read, t2 write;<\/code> \uff0c\u53ef\u4ee5\u7528 <code>unlock tables<\/code> \u4e3b\u52a8\u91ca\u653e\u9501\uff0c\u4e5f\u53ef\u4ee5\u5728\u5ba2\u6237\u7aef\u65ad\u5f00\u7684\u65f6\u5019\u81ea\u52a8\u91ca\u653e\u3002lock tables \u8bed\u6cd5\u9664\u4e86\u9650\u5236\u5176\u4ed6\u7ebf\u7a0b\u7684\u8bfb\u5199\u5916\uff0c\u4e5f\u9650\u5b9a\u4e86\u672c\u7ebf\u7a0b\u63a5\u4e0b\u6765\u7684\u64cd\u4f5c\u5bf9\u8c61\uff0c\u4f8b\u5982\u524d\u9762\u7684\u8bed\u53e5\u9650\u5b9a\u4e86\u5bf9 t1 \u53ea\u80fd\u8fdb\u884c\u8bfb\u3001 t2 \u53ef\u4ee5\u8bfb\u5199\uff0c\u4e5f\u4e0d\u80fd\u8bbf\u95ee\u5176\u4ed6\u8868\u3002<\/p>\n<p>\u5143\u6570\u636e\u9501 MDL \u662f\u81ea\u52a8\u52a0\u9501\u3001\u91ca\u653e\u9501\u7684\uff0c\u5f53\u5bf9\u4e00\u4e2a\u8868\u505a \u589e\u5220\u6539\u67e5 \u64cd\u4f5c\u7684\u65f6\u5019\u52a0 MDL \u8bfb\u9501\uff0c\u5f53\u5bf9\u8868\u7ed3\u6784\u505a\u53d8\u66f4\u64cd\u4f5c\u7684\u65f6\u5019\uff0c\u52a0 MDL \u5199\u9501\u3002<\/p>\n<p>\u4e8b\u52a1\u4e2d\u7684 MDL \u9501\uff0c\u5728\u8bed\u53e5\u6267\u884c\u5f00\u59cb\u65f6\u7533\u8bf7\uff0c\u4f46\u662f\u8bed\u53e5\u7ed3\u675f\u540e\u5e76\u4e0d\u4f1a\u9a6c\u4e0a\u91ca\u653e\uff0c\u800c\u4f1a\u7b49\u5230\u6574\u4e2a\u4e8b\u52a1\u63d0\u4ea4\u540e\u518d\u91ca\u653e\u3002<\/p>\n<p>MySQL online DDL \u7684\u8fc7\u7a0b\uff1a<br \/>\n1. \u83b7\u53d6 MDL \u5199\u9501<br \/>\n2. \u964d\u7ea7\u6210 MDL \u8bfb\u9501<br \/>\n3. \u771f\u6b63\u505a DDL<br \/>\n4. \u5347\u7ea7\u6210 MDL \u5199\u9501<br \/>\n5. \u91ca\u653e MDL \u5199\u9501<\/p>\n<p>\u7b2c3\u6b65\u5360\u4e86 DDL \u7edd\u5927\u90e8\u5206\u65f6\u95f4\uff0c\u5728\u8fd9\u671f\u95f4\u8fd9\u4e2a\u8868\u53ef\u4ee5\u6b63\u5e38\u8bfb\u5199\u6570\u636e\uff0c\u56e0\u6b64\u79f0\u4e3a online \u3002<\/p>\n<p>\u4e0a\u9762\u6b65\u9aa4 1\u4e0e2\u30014\u4e0e5 \u4e4b\u6240\u4ee5\u9700\u8981\u662f\u56e0\u4e3a \u8bfb\u9501\u4e0e\u5199\u9501\u3001 \u5199\u9501\u4e0e\u5199\u9501 \u90fd\u662f\u4e92\u65a5\u7684\uff0c\u4e3a\u4e86\u9632\u6b62\u540c\u4e00\u65f6\u95f4\u6709\u4e24\u4e2a DDL \u540c\u65f6\u8fdb\u884c\u6240\u5fc5\u987b\u7684\u3002<br \/>\n\u628a\u5199\u9501\u964d\u7ea7\u4e3a\u8bfb\u9501\u662f\u4e3a\u4e86\u8ba9\u589e\u5220\u6539\u67e5\u53ef\u4ee5\u540c\u65f6\u8fdb\u884c\u30024\u4e0e5\u662f\u56e0\u4e3a\u8fd8\u8981\u505a\u4e00\u4e9b\u8868\u7ed3\u6784\u4fee\u6539\u3002<\/p>\n<h2>\u884c\u9501<\/h2>\n<p>\u4e24\u9636\u6bb5\u9501\u534f\u8bae\uff1a\u5728 InnoDB \u4e8b\u52a1\u4e2d\uff0c\u884c\u9501\u662f\u5728\u9700\u8981\u7684\u65f6\u5019\u624d\u52a0\u4e0a\u53bb\u7684\uff0c\u76f4\u5230\u4e8b\u52a1\u7ed3\u675f\uff08\u63d0\u4ea4\u6216\u56de\u6eda\uff09\u624d\u91ca\u653e\u3002<\/p>\n<p>\u5982\u679c\u4e8b\u52a1\u4e2d\u9700\u8981\u9501\u591a\u4e2a\u884c\uff0c\u628a\u6700\u53ef\u80fd\u9020\u6210\u9501\u51b2\u7a81\u3001\u5f71\u54cd\u5e76\u53d1\u5ea6\u7684\u9501\u5c3d\u91cf\u5f80\u540e\u653e\u3002\uff08\u8d8a\u5f80\u540e\uff0c\u79bb\u91ca\u653e\u9501\u7684\u65f6\u95f4\u5c31\u8d8a\u77ed\uff0c\u8fd9\u6837\u5c31\u7f29\u77ed\u4e86\u6301\u6709\u5173\u952e\u9501\u7684\u65f6\u95f4\u957f\u5ea6\u3002\uff09<\/p>\n<p>\u51fa\u73b0\u6b7b\u9501\u4ee5\u540e\uff0c\u6709\u4e24\u79cd\u7b56\u7565\uff1a<\/p>\n<ul>\n<li>\n<ol>\n<li>\u76f4\u63a5\u8fdb\u5165\u7b49\u5f85\u76f4\u5230\u8d85\u65f6\u3002\u8d85\u65f6\u65f6\u95f4\u53ef\u4ee5\u901a\u8fc7\u53c2\u6570 <code>innodb_lock_wait_timeout<\/code> \u6765\u8bbe\u7f6e\uff0cInnoDB \u9ed8\u8ba4\u503c\u662f 50 \u79d2\u3002<\/li>\n<\/ol>\n<\/li>\n<li>\n<ol>\n<li>\u53d1\u8d77\u6b7b\u9501\u68c0\u6d4b\uff0c\u53d1\u73b0\u6b7b\u9501\u540e\uff0c\u4e3b\u52a8\u56de\u6eda\u6b7b\u9501\u94fe\u6761\u4e2d\u7684\u67d0\u4e00\u4e2a\u4e8b\u52a1\uff0c\u8ba9\u5176\u4ed6\u4e8b\u52a1\u5f97\u4ee5\u7ee7\u7eed\u8fdb\u884c\u3002\u53c2\u6570 <code>innodb_deadlock_detect=on<\/code> \u8868\u793a\u5f00\u542f\u8fd9\u4e2a\u903b\u8f91\u3002<\/li>\n<\/ol>\n<\/li>\n<\/ul>\n<p>\u6b7b\u9501\u68c0\u6d4b\u7684\u590d\u6742\u5ea6\uff1a\u6bcf\u4e2a\u65b0\u6765\u7684\u88ab\u5835\u4f4f\u7684\u7ebf\u7a0b\uff0c\u90fd\u8981\u5224\u7b49\u4f1a\u4e0d\u4f1a\u7531\u4e8e\u81ea\u5df1\u7684\u52a0\u5165\u5bfc\u81f4\u4e86\u6b7b\u9501\uff0c\u8fd9\u4e2a\u65f6\u95f4\u590d\u6742\u5ea6\u662f O(n) \u3002<\/p>\n<p>\u907f\u514d\u6b7b\u9501\u68c0\u6d4b\u7684\u601d\u8def\uff1a<\/p>\n<ol>\n<li>\u4e34\u65f6\u5173\u95ed\u6b7b\u9501\u68c0\u6d4b\uff1b<\/li>\n<li>\u63a7\u5236\u5e76\u53d1\u5ea6\uff1a\u53ef\u4ee5\u628a\u5bf9\u540c\u4e00\u4e2a\u884c\u9501\u7684\u8bbf\u95ee\u9650\u5236\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u5e76\u53d1\u5ea6\uff0c\u4ece\u800c\u4f7f\u68c0\u6d4b\u6210\u672c\u5f88\u4f4e\u3002\n<ul>\n<li>\u5ba2\u6237\u7aef\u63a7\u5236\uff1a\u5982\u679c\u6709\u591a\u4e2a\u5ba2\u6237\u7aef\uff0c\u6548\u679c\u4e0d\u597d\uff1b<\/li>\n<li>\u5728\u4e2d\u95f4\u4ef6\u5b9e\u73b0\uff1b<\/li>\n<li>\u5728 MySQL \u91cc\u9762\u5b9e\u73b0\uff0c\u5bf9\u4e8e\u76f8\u540c\u884c\u7684\u66f4\u65b0\uff0c\u5728\u8fdb\u5165\u5f15\u64ce\u4e4b\u524d\u6392\u961f\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\u5728\u4e1a\u52a1\u903b\u8f91\u4e0a\u5c06\u4e00\u884c\u6539\u6210\u591a\u884c\u6765\u51cf\u5c11\u9501\u51b2\u7a81\u3002\u6bd4\u5982 JDK \u7684\u7d2f\u52a0\u5668 LongAddr \uff0c\u5185\u90e8\u7ef4\u62a4\u4e86\u591a\u4e2a\u69fd\u4f5c\u4e3a\u8ba1\u6570\u5668\u3002<\/li>\n<\/ol>\n<p>InnoDB \u7684\u884c\u7ea7\u9501\u662f\u901a\u8fc7\u7d22\u5f15\u52a0\u8f7d\u7684\uff0c\u5373\u884c\u9501\u662f\u52a0\u5728\u7d22\u5f15\u54cd\u5e94\u7684\u884c\u4e0a\u7684\uff0c\u5982\u679c\u5bf9\u5e94\u7684 update \u8bed\u53e5\u6ca1\u6709\u8d70\u7d22\u5f15\uff0c\u5219\u4f1a\u52a0\u8868\u9501\u3002<br \/>\n\u5bf9\u7d22\u5f15\u626b\u63cf\u5f97\u5230\u7684\u6bcf\u4e00\u884c\u52a0\u9501\uff0c\u5728\u4e8b\u52a1\u7ed3\u675f\u65f6\u91ca\u653e\u3002<\/p>\n<pre><code class=\"sql\">CREATE TABLE `geek` (\n  `a` int(11) NOT NULL,\n  `b` int(11) NOT NULL,\n  `c` int(11) NOT NULL,\n  `d` int(11) NOT NULL,\n  PRIMARY KEY (`a`,`b`),\n  KEY `c` (`c`),\n  KEY `ca` (`c`,`a`),\n  KEY `cb` (`c`,`b`)\n) ENGINE=InnoDB;\n\ninsert into geek (a, b, c, d) values (0, 1, 2, 3);\ninsert into geek (a, b, c, d) values (1, 2, 3, 4);\n<\/code><\/pre>\n<p>\u5206\u522b\u5f00\u4e24\u4e2a\u547d\u4ee4\u884c\u5ba2\u6237\u7aef\uff0c\u5728\u7b2c\u4e00\u4e2a\u5ba2\u6237\u7aef\u6267\u884c\u4e0b\u9762\u5230 <code>for update<\/code> \u8bed\u53e5\uff0c<\/p>\n<pre><code>begin;\nselect * from geek where a = 0 and b = 1 for update;\n<\/code><\/pre>\n<p>\u7136\u540e\u5728\u7b2c2\u4e2a\u5ba2\u6237\u7aef\u6267\u884c<\/p>\n<pre><code class=\"sql\">select * from geek where a = 1 and b = 2 for update;\n<\/code><\/pre>\n<p>\u4f1a\u53d1\u73b0\u7acb\u5373\u5c31\u6267\u884c\u5b8c\u4e86\uff0c\u8bf4\u660e\u4e3b\u952e\u4e3a (1, 2) \u7684\u8bb0\u5f55\u5e76\u6ca1\u6709\u88ab\u7b2c\u4e00\u4e2a\u5ba2\u6237\u7aef\u9501\u4f4f\u3002<\/p>\n<p>\u5728\u7b2c\u4e8c\u4e2a\u5ba2\u6237\u7aef\u7ee7\u7eed\u6267\u884csql<\/p>\n<pre><code class=\"sql\">select * from geek where a = 0 and b = 1 for update;\n<\/code><\/pre>\n<p>\u4f1a\u53d1\u73b0\u88ab\u963b\u585e\uff0c<br \/>\n<img loading=\"lazy\" decoding=\"async\" width=\"1138\" height=\"269\" src=\"https:\/\/coderbee.net\/wp-content\/uploads\/2019\/01\/two-phase-lock.png\" alt=\"\" class=\"alignnone size-full wp-image-1782\" \/><\/p>\n<p>\u5728\u7b2c\u4e00\u4e2a\u5ba2\u6237\u7aef\u6267\u884c commit \u540e\u4f1a\u770b\u5230\u7b2c\u4e8c\u4e2a\u5ba2\u6237\u7aef\u4e5f\u9a6c\u4e0a\u6267\u884c\u5b8c\u6210\uff0c\u8bf4\u660e\u7b2c\u4e00\u4e2a\u5ba2\u6237\u7aef\u9501\u4f4f\u7684\u8bb0\u5f55\u662f\u5728\u4e8b\u52a1\u63d0\u4ea4\u7684\u65f6\u5019\u91ca\u653e\u7684\u3002<\/p>\n<p>\u5bf9\u4e8e\u5168\u8868\u67e5\u8be2\uff0c\u5373\u4f7f\u8868\u4e2d\u53ea\u6709\u5f88\u5c11\u7684\u8bb0\u5f55\uff0c\u4e5f\u4f1a\u52a0\u8868\u9501\uff0c\u4f1a\u5bfc\u81f4\u63d2\u5165\u3001\u66f4\u65b0\u64cd\u4f5c\u963b\u585e\uff0c\u5982\u4e0b\uff1a<br \/>\n<img loading=\"lazy\" decoding=\"async\" width=\"1121\" height=\"187\" src=\"https:\/\/coderbee.net\/wp-content\/uploads\/2019\/01\/tow-phase-lock-block-insert.png\" alt=\"\" class=\"alignnone size-full wp-image-1780\" \/><\/p>\n<p>\u867d\u7136\u53ea\u66f4\u65b0\u4e00\u6761\u8bb0\u5f55\uff0c\u4ecd\u7136\u4f1a\u52a0\u8868\u9501\uff0c\u5bfc\u81f4\u5176\u4ed6\u66f4\u65b0\u963b\u585e\u6216\u8d85\u65f6\uff1a<br \/>\n<img loading=\"lazy\" decoding=\"async\" width=\"1132\" height=\"168\" src=\"https:\/\/coderbee.net\/wp-content\/uploads\/2019\/01\/tow-phase-lock-block-update.png\" alt=\"\" class=\"alignnone size-full wp-image-1781\" \/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u9501 \u6839\u636e\u52a0\u9501\u7684\u8303\u56f4\uff0cMySQL \u91cc\u9762\u7684\u9501\u5927\u81f4\u53ef\u4ee5\u5206\u6210\u5168\u5c40\u9501\u3001\u8868\u7ea7\u9501\u548c\u884c\u9501\u4e09\u7c7b\u3002  &hellip; <a href=\"https:\/\/coderbee.net\/index.php\/db\/20190122\/1779\">\u7ee7\u7eed\u9605\u8bfb <span 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