{"id":2089,"date":"2023-04-01T21:56:52","date_gmt":"2023-04-01T13:56:52","guid":{"rendered":"https:\/\/www.appblog.cn\/?p=2089"},"modified":"2023-04-06T14:49:26","modified_gmt":"2023-04-06T06:49:26","slug":"mysql-locking-practice","status":"publish","type":"post","link":"https:\/\/www.appblog.cn\/index.php\/2023\/04\/01\/mysql-locking-practice\/","title":{"rendered":"MySQL\u52a0\u9501\u5b9e\u8df5"},"content":{"rendered":"

\u95f4\u9699\u9501\uff08Gap Lock\uff09<\/h2>\n

\u9996\u5148\u8c08\u8c08\u95f4\u9699\u9501\u662f\u4ec0\u4e48\u3002<\/p>\n

\u95f4\u9699\u9501\u662f\u4e13\u95e8\u7528\u4e8e\u89e3\u51b3\u5e7b\u8bfb\u8fd9\u79cd\u95ee\u9898\u7684\u9501\uff0c\u5b83\u9501\u7684\u4e86\u884c\u4e0e\u884c\u4e4b\u95f4\u7684\u95f4\u9699\uff0c\u80fd\u591f\u963b\u585e\u65b0\u63d2\u5165\u7684\u64cd\u4f5c\uff0c\u540c\u65f6\u95f4\u9699\u9501\u7684\u5f15\u5165\u4e5f\u5e26\u6765\u4e86\u4e00\u4e9b\u65b0\u7684\u95ee\u9898\uff0c\u6bd4\u5982\uff1a\u964d\u4f4e\u5e76\u53d1\u5ea6\uff0c\u53ef\u80fd\u5bfc\u81f4\u6b7b\u9501\u3002<\/p>\n

\u8fd9\u91cc\u7279\u522b\u8bb0\u5f55\u4e0b\u8bfb\u8bfb\u4e0d\u4e92\u65a5\uff0c\u8bfb\u5199\/\u5199\u8bfb\/\u5199\u5199\u662f\u4e92\u65a5\u7684\uff0c\u4f46\u662f\u95f4\u9699\u9501\u4e4b\u95f4\u662f\u4e0d\u51b2\u7a81\u7684\uff0c\u95f4\u9699\u9501\u4f1a\u963b\u585e\u63d2\u5165\u64cd\u4f5c\uff0c\u53e6\u5916\uff0c\u95f4\u9699\u9501\u5728\u53ef\u91cd\u590d\u8bfb\u7ea7\u522b\u4e0b\u624d\u662f\u6709\u6548\u7684\u3002<\/p>\n

<\/p>\n

\u52a0\u9501\u7684\u89c4\u5219<\/h2>\n

MySQL\u52a0\u9501\u603b\u7ed3\u4e0b\u6765\u5305\u62ec\u4ee5\u4e0b\u65b9\u9762\u5305\u62ec\u4e24\u4e2a\u539f\u5219\u3001\u4e24\u4e2a\u4f18\u5316\u3001\u4e00\u4e2abug\uff1a<\/p>\n

\u539f\u52191<\/strong>: \u52a0\u9501\u7684\u57fa\u672c\u5355\u4f4d\u662fnext-key lock\u3002next-key lock \u662f\u524d\u5f00\u540e\u95ed\u533a\u95f4\uff0cnext-key lock\u662f\u884c\u9501\u548c\u95f4\u9699\u9501\u7684\u7ec4\u5408<\/p>\n

\u539f\u52192<\/strong>: \u67e5\u627e\u8fc7\u7a0b\u4e2d\u8bbf\u95ee\u5230\u7684\u5bf9\u8c61\u624d\u4f1a\u52a0\u9501–\u5bf9\u4e8e\u672a\u547d\u4e2d\u7d22\u5f15\u7684\u67e5\u8be2\u8981\u8d70\u5168\u8868\u626b\u63cf\uff0c\u8fd9\u79cd\u5728\u626b\u63cf\u524d\u5c31\u7ed9\u5168\u8868\u52a0\u4e0a\u4e86next-key lock<\/p>\n

\u4f18\u53161<\/strong>: \u7d22\u5f15\u4e0a\u7684\u7b49\u503c\u67e5\u8be2\uff0c\u7ed9\u552f\u4e00\u7d22\u5f15\u4e0a\u52a0\u9501\u7684\u65f6\u5019\uff0cnext-key lock\u4f1a\u9000\u5316\u4e3a\u884c\u9501\uff0c\u662f\u5339\u914d\u4e0a\u7684\u65f6\u5019\uff0c\u5982\u679c\u6ca1\u6709\u5339\u914d\u4e0a\uff0c\u81ea\u7136\u4e5f\u5c31\u4e0d\u4f1a\u9000\u5316\u4e3a\u884c\u9501\u4e86\uff0c\u6b64\u65f6\u4f1a\u7528\u5230\u4f18\u53162\uff0c\u4ece\u800c\u9000\u5316\u6210\u95f4\u9699\u9501<\/p>\n

\u4f18\u53162<\/strong>: \u7d22\u5f15\u4e0a\u7684\u7b49\u503c\u67e5\u8be2\uff0c\u5411\u53f3\u904d\u5386\u65f6\u4e14\u6700\u540e\u4e00\u4e2a\u503c\u4e0d\u6ee1\u8db3\u7b49\u503c\u6761\u4ef6\u7684\u65f6\u5019\uff0cnext-key lock\u4f1a\u9000\u5316\u4e3a\u95f4\u9699\u9501<\/p>\n

\u4e00\u4e2abug<\/strong>\uff1a\u552f\u4e00\u7d22\u5f15\u4e0a\u7684\u8303\u56f4\u67e5\u8be2\u4f1a\u8bbf\u95ee\u5230\u4e0d\u6ee1\u8db3\u6761\u4ef6\u7684\u7b2c\u4e00\u4e2a\u503c\u4e3a\u6b62\uff08\u552f\u4e00\u7d22\u5f15\u8303\u56f4\u9501\u7684bug\u5728\u6700\u65b0\u76848.0.18\u5df2\u7ecf\u4fee\u590d\uff09<\/p>\n

\u5728\u540e\u9762\u7684\u81ea\u5df1\u5b9e\u8df5\u8fc7\u7a0b\u4e2d\u7262\u8bb0MySQL\u52a0\u9501\u7684\u89c4\u5219\u624d\u80fd\u66f4\u597d\u7684\u8fdb\u884c\u7406\u89e3\u3002<\/p>\n

\u52a8\u624b\u5b9e\u8df5<\/h2>\n

\u51c6\u5907<\/h3>\n
mysql> CREATE TABLE `t` (\n\u00a0 \u00a0 ->\u00a0 `id` int(11) NOT NULL,\n\u00a0 \u00a0 ->\u00a0 `c` int(11) DEFAULT NULL,\n\u00a0 \u00a0 ->\u00a0 `d` int(11) DEFAULT NULL,\n\u00a0 \u00a0 ->\u00a0 PRIMARY KEY (`id`),\n\u00a0 \u00a0 ->\u00a0 KEY `c` (`c`)\n\u00a0 \u00a0 -> ) ENGINE=InnoDB;\nQuery OK, 0 rows affected (0.02 sec)\nmysql>\nmysql> insert into t values(0,0,0),(5,5,5),\n\u00a0 \u00a0 -> (10,10,10),(15,15,15),(20,20,20),(25,25,25);\nQuery OK, 6 rows affected (0.00 sec)\nRecords: 6\u00a0 Duplicates: 0\u00a0 Warnings: 0\nmysql> select * from t;\n+----+------+------+\n| id | c    | d    |\n+----+------+------+\n|  0 |    0 |    0 |\n|  5 |    5 |    5 |\n| 10 |   10 |   10 |\n| 15 |   15 |   15 |\n| 20 |   20 |   20 |\n| 25 |   25 |   25 |\n+----+------+------+\n6 rows in set (0.00 sec)<\/code><\/pre>\n
\u7b49\u503c\u67e5\u8be2\u95f4\u9699\u9501<\/h3>\n
session1\uff08\u7b2c\u4e00\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> begin;\nQuery OK, 0 rows affected (0.00 sec)\n\nmysql> update t set d=d+1 where id=7;\nQuery OK, 0 rows affected (0.00 sec)\nRows matched: 0  Changed: 0  Warnings: 0<\/code><\/pre>\n
session2\uff08\u7b2c\u4e8c\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> insert into t values(8,8,8);\n(blocked)\nERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction<\/code><\/pre>\n
session3\uff08\u7b2c\u4e09\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> update t set d=d+1 where id=10;\nQuery OK, 1 row affected (0.00 sec)\nRows matched: 1  Changed: 1  Warnings: 0<\/code><\/pre>\n
\u5206\u6790\uff1a<\/p>\n
\u8868t\u4e2d\u65e0id=7<\/code>\u7684\u8bb0\u5f55<\/p>\n
1\u3001\u6839\u636enext-key lock\u539f\u5219\uff0c\u5de6\u5f00\u53f3\u95edsession1\u52a0\u9501\u8303\u56f4(5, 10]<\/code>
\n2\u3001\u7d22\u5f15\u4e0a\u7684\u7b49\u503c\u67e5\u8be2\uff0c\u5411\u53f3\u904d\u5386\u65f6\u4e14\u6700\u540e\u4e00\u4e2a\u503cid=10<\/code>\u65f6\u4e0d\u6ee1\u8db3\u7b49\u503c\u6761\u4ef6\u7684\u65f6\u5019\uff0cnext-key lock\u4f1a\u9000\u5316\u4e3a\u95f4\u9699\u9501\uff0c\u56e0\u6b64\u52a0\u9501\u8303\u56f4\u4e3a(5, 10)<\/code><\/p>\n
\u7ed3\u8bba\uff1asession 2 \u8981\u5f80\u8fd9\u4e2a\u95f4\u9699\u91cc\u9762\u63d2\u5165id=8<\/code>\u7684\u8bb0\u5f55\u4f1a\u88ab\u9501\u4f4f\uff0c\u4f46\u662f session 3 \u4fee\u6539id=10<\/code>\u8fd9\u884c\u662f\u53ef\u4ee5\u7684\u3002<\/p>\n
\u975e\u552f\u4e00\u7d22\u5f15\u7b49\u503c\u9501<\/h3>\n
session1\uff08\u7b2c\u4e00\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> begin;\nQuery OK, 0 rows affected (0.00 sec)\n\nmysql> select id from t where c=5 lock in share mode;\n+----+\n| id |\n+----+\n|  5 |\n+----+\n1 row in set (0.00 sec)<\/code><\/pre>\n
session2\uff08\u7b2c\u4e8c\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> update t set d=d+1 where id=5;\nQuery OK, 1 row affected (0.01 sec)\nRows matched: 1  Changed: 1  Warnings: 0<\/code><\/pre>\n
session3\uff08\u7b2c\u4e09\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> insert into t values(7,7,7);\n(blocked)\nERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction<\/code><\/pre>\n
\u5206\u6790\uff1asession 1 \u8981\u7ed9\u7d22\u5f15 c\u4e0ac=5<\/code>\u7684\u8fd9\u4e00\u884c\u52a0\u4e0a\u8bfb\u9501<\/p>\n
1\u3001\u9996\u5148\u6839\u636enext-key lock \u539f\u5219\uff0c\u5de6\u5f00\u53f3\u95ed \u7ed9c\u7d22\u5f15\u4e3a(0, 5]<\/code>\u52a0\u9501\u3002<\/p>\n
2\u3001\u56e0\u4e3ac\u4e3a\u666e\u901a\u7d22\u5f15\uff08\u975e\u552f\u4e00\u7d22\u5f15\uff09\uff0c\u7d22\u5f15\u4e0a\u7684\u7b49\u503c\u67e5\u8be2\uff0c\u5411\u53f3\u904d\u5386\u65f6\u4e14\u6700\u540e\u4e00\u4e2a\u503c\u4e0d\u6ee1\u8db3c=10<\/code>\u7684\u7b49\u503c\u6761\u4ef6\u7684\u65f6\u5019\uff0cnext-key lock\u4f1a\u9000\u5316\u4e3a\u95f4\u9699\u9501\uff0c\u6b64\u65f6\u8bbf\u95ee\u5230\u7684\u5bf9\u8c61\u90fd\u52a0\u9501\uff0c\u5373\u7ed9c\u4e3a(5, 10]<\/code>\u90fd\u8981\u52a0next-key lock \u9501<\/p>\n
3\u3001\u6839\u636e\u4f18\u53162\uff0c\u5411\u53f3\u904d\u5386\u6700\u540e\u4e00\u4e2a\u4e0d\u6ee1\u8db3\u7684\u503c\u65f6\uff0c\u9000\u5316\u4e3a\u95f4\u9699\u9501\uff0c(5, 10)<\/code>\uff1b\u6ce8\u610f\u524d\u9762\u5206\u6790\u7684(0, 5]<\/code>\u95f4\u9699\u9501\u8fd8\u662f\u5b58\u5728\u7684\uff0c\u6b64\u65f6\u52a0\u9501\u7684\u8303\u56f4\u4e3ac\u7d22\u5f15\u4e0a(0, 5]<\/code>\u548c(5, 10)<\/code>\u7684\u95f4\u9699\u9501\u3002<\/p>\n
4\u3001\u6839\u636e\u539f\u52192\uff0c\u8bbf\u95ee\u5230\u7684\u5bf9\u8c61\uff08\u8fd9\u91cc\u6307c=5<\/code>\u7d22\u5f15\u8fd9\u4e00\u5217\uff09\u624d\u4f1a\u52a0\u9501\u3002\u8fd9\u4e2a\u67e5\u8be2\u4f7f\u7528\u7684\u662f\u8986\u76d6\u7d22\u5f15\uff0c\u56e0\u6b64\u5e76\u4e0d\u9700\u8981\u8bbf\u95ee\u4e3b\u952e\u7d22\u5f15\uff0c\u6240\u4ee5session2\u53ef\u4ee5\u6267\u884c\u6210\u529f\uff0c\u8fd9\u6837\u4e5f\u9a8c\u8bc1\u4e86\u8bbf\u95ee\u5230\u7684\u5bf9\u8c61\u624d\u4f1a\u52a0\u9501\uff08\u8bbf\u95ee\u5230\u7684\u5bf9\u8c61\u624d\u4f1a\u52a0\u9501\uff0c\u8fd9\u4e2a\u201c\u5bf9\u8c61\u201d\u6307\u7684\u662fc\u5217\uff0c\u4e0d\u662f \u8bb0\u5f55\u884c\u3002\u8865\u5145\u4e00\u4e0b\uff1a\u52a0\u9501\uff0c\u662f\u52a0\u5728\u7d22\u5f15\u4e0a\u7684\u3002\u5217\u4e0a\uff0c\u6709\u7d22\u5f15\uff0c\u5c31\u52a0\u5728\u7d22\u5f15\u4e0a\uff0c\u5217\u4e0a\uff0c\u6ca1\u6709\u7d22\u5f15\uff0c\u5c31\u52a0\u5728\u4e3b\u952e\u4e0a\uff09<\/p>\n
\u8fd9\u91cc\u8981\u7279\u6b8a\u8bf4\u660e\u4e0b lock in share mode \u53ea\u9501\u8986\u76d6\u7d22\u5f15\uff0c\u4f46\u662f\u5982\u679c\u662f for update \u5c31\u4e0d\u4e00\u6837\u4e86\u3002\u6267\u884c for update \u65f6\uff0c\u7cfb\u7edf\u4f1a\u8ba4\u4e3a\u4f60\u63a5\u4e0b\u6765\u8981\u66f4\u65b0\u6570\u636e\uff0c\u56e0\u6b64\u4f1a\u987a\u4fbf\u7ed9\u4e3b\u952e\u7d22\u5f15\u4e0a\u6ee1\u8db3\u6761\u4ef6\u7684\u884c\u52a0\u4e0a\u884c\u9501\u3002<\/p>\n
\u6570\u636e\u884c\u52a0\u8bfb\u9501\uff0c\u5982\u679c\u67e5\u8be2\u5b57\u6bb5\u4f7f\u7528\u4e86\u8986\u76d6\u7d22\u5f15\uff0c\u8bbf\u95ee\u5230\u7684\u5bf9\u8c61\u53ea\u6709\u666e\u901a\u7d22\u5f15\uff0c\u5e76\u6ca1\u6709\u8bbf\u95ee\u5230\u4e3b\u952e\u7d22\u5f15\uff0c\u5219\u4e0d\u4f1a\u9501\u4e3b\u952e\u7d22\u5f15\u3002\u5982\u679c\u6ca1\u6709\u4f7f\u7528\u8986\u76d6\u7d22\u5f15\uff0c\u5219\u4f1a\u56de\u8868\u67e5\u8be2\uff0c\u8bbf\u95ee\u5230\u4e3b\u952e\u7d22\u5f15\uff0c\u8fd9\u6837\u4e3b\u952e\u7d22\u5f15\u4e5f\u4f1a\u52a0\u9501\u3002<\/p>\n
\u4e3b\u952e\u7d22\u5f15\u8303\u56f4\u9501<\/h3>\n
session1\uff08\u7b2c\u4e00\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> begin;\nQuery OK, 0 rows affected (0.00 sec)\n\nmysql> select * from t where id>=10 and id<11 for update;\n+----+------+------+\n| id | c    | d    |\n+----+------+------+\n| 10 |   10 |   11 |\n+----+------+------+\n1 row in set (0.00 sec)<\/code><\/pre>\n
session2\uff08\u7b2c\u4e8c\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> insert into t values(13,13,13);\n(blocked)\nERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction<\/code><\/pre>\n
session3\uff08\u7b2c\u4e09\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> update t set d=d+1 where id=15;\n(blocked)\nERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction<\/code><\/pre>\n
\u5206\u6790\uff1a<\/p>\n
1\u3001\u5f00\u59cb\u6267\u884c \u8bbf\u95eeid=10<\/code>\u52a0\u9501\u8303\u56f4id\u7d22\u5f15\u4e0a(5, 10]<\/code> next-key lock \u7531\u4e8eid\u552f\u4e00\u7d22\u5f15\u9000\u5316\u4e3a\u884c\u9501id=10<\/code><\/p>\n
2\u3001\u8303\u56f4\u67e5\u8be2\u5411\u540e\u67e5\u627e \u7b2c\u4e00\u4e2a\u4e0d\u6ee1\u8db3\u6761\u4ef6\u7684\u503cid=15<\/code>\u52a0\u9501\u8303\u56f4(10, 15]<\/code><\/p>\n
\u7ed3\u8bba\uff1asession2\u3001session3 \u963b\u585e<\/p>\n
\u975e\u552f\u4e00\u7d22\u5f15\u8303\u56f4\u9501<\/h3>\n
session1\uff08\u7b2c\u4e00\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> begin;\nQuery OK, 0 rows affected (0.00 sec)\n\nmysql> select * from t where c>=10 and c<11 for update;\n+----+------+------+\n| id | c    | d    |\n+----+------+------+\n| 10 |   10 |   11 |\n+----+------+------+\n1 row in set (0.00 sec)<\/code><\/pre>\n
session2\uff08\u7b2c\u4e8c\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> insert into t values(8,8,8);\n(blocked)\nERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction<\/code><\/pre>\n
session3\uff08\u7b2c\u4e09\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> update t set d=d+1 where c=15;\n(blocked)\nERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction<\/code><\/pre>\n
\u5206\u6790\uff1a\u5bf9c\u5b57\u6bb5\u52a0\u9501\uff08\u975e\u552f\u4e00\u7d22\u5f15\uff09<\/p>\n
\u5728\u7b2c\u4e00\u6b21\u7528c=10<\/code>\u5b9a\u4f4d\u8bb0\u5f55\u7684\u65f6\u5019\uff0c\u7d22\u5f15 c \u4e0a\u52a0\u4e86(5, 10]<\/code>\u8fd9\u4e2a next-key lock \u540e\uff0c\u7531\u4e8e\u7d22\u5f15 c \u662f\u975e\u552f\u4e00\u7d22\u5f15\uff0c\u6ca1\u6709\u4f18\u5316\u89c4\u5219\uff0c\u4e5f\u5c31\u662f\u8bf4\u4e0d\u4f1a\u8715\u53d8\u4e3a\u884c\u9501\uff0c\u56e0\u6b64\u6700\u7ec8 sesion A \u52a0\u7684\u9501\u662f\uff0c\u7d22\u5f15 c \u4e0a\u7684(5, 10]<\/code>\u548c(10, 15]<\/code>\u8fd9\u4e24\u4e2a next-key lock\u3002<\/p>\n
\u552f\u4e00\u7d22\u5f15\u8303\u56f4\u9501 bug<\/h3>\n
session1\uff08\u7b2c\u4e00\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> begin;\nQuery OK, 0 rows affected (0.00 sec)\n\nmysql> select * from t where id>10 and id<=15 for update;\n+----+------+------+\n| id | c    | d    |\n+----+------+------+\n| 15 |   15 |   15 |\n+----+------+------+\n1 row in set (0.00 sec)<\/code><\/pre>\n
session2\uff08\u7b2c\u4e8c\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> update t set d=d+1 where id=20;\n(blocked)\nERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction<\/code><\/pre>\n
session3\uff08\u7b2c\u4e09\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> insert into t values(16,16,16);\n(blocked)\nERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction<\/code><\/pre>\n
\u5206\u6790\uff1a<\/p>\n
1\u3001session A \u662f\u4e00\u4e2a\u8303\u56f4\u67e5\u8be2\uff0c\u6309\u7167\u539f\u5219 1 \u7684\u8bdd\uff0c\u5e94\u8be5\u662f\u7d22\u5f15 id \u4e0a\u53ea\u52a0(10, 15]<\/code>\u8fd9\u4e2a next-key lock\uff0c\u5e76\u4e14\u56e0\u4e3a id \u662f\u552f\u4e00\u952e\uff0c\u6240\u4ee5\u5faa\u73af\u5224\u65ad\u5230id=15<\/code>\u8fd9\u4e00\u884c\u5c31\u5e94\u8be5\u505c\u6b62\u4e86\u3002<\/p>\n
2\u3001\u4f46\u662f\u5b9e\u73b0\u4e0a\uff0cInnoDB \u4f1a\u5f80\u524d\u626b\u63cf\u5230\u7b2c\u4e00\u4e2a\u4e0d\u6ee1\u8db3\u6761\u4ef6\u7684\u884c\u4e3a\u6b62\uff0c\u4e5f\u5c31\u662fid=20<\/code>\u3002\u800c\u4e14\u7531\u4e8e\u8fd9\u662f\u4e2a\u8303\u56f4\u626b\u63cf\uff0c\u56e0\u6b64\u7d22\u5f15 id \u4e0a\u7684(15, 20]<\/code>\u8fd9\u4e2a next-key lock \u4e5f\u4f1a\u88ab\u9501\u4e0a\u3002<\/p>\n
\u6240\u4ee5\u4f60\u770b\u5230\u4e86\uff0csession B \u8981\u66f4\u65b0id=20<\/code>\u8fd9\u4e00\u884c\uff0c\u662f\u4f1a\u88ab\u9501\u4f4f\u7684\u3002\u540c\u6837\u5730\uff0csession C \u8981\u63d2\u5165id=16<\/code>\u7684\u4e00\u884c\uff0c\u4e5f\u4f1a\u88ab\u9501\u4f4f\u3002<\/p>\n
\u7167\u7406\u8bf4\uff0c\u8fd9\u91cc\u9501\u4f4fid=20<\/code>\u8fd9\u4e00\u884c\u7684\u884c\u4e3a\uff0c\u5176\u5b9e\u662f\u6ca1\u6709\u5fc5\u8981\u7684\u3002\u56e0\u4e3a\u626b\u63cf\u5230id=15<\/code>\uff0c\u5c31\u53ef\u4ee5\u786e\u5b9a\u4e0d\u7528\u5f80\u540e\u518d\u627e\u4e86\u3002\u4f46\u5b9e\u73b0\u4e0a\u8fd8\u662f\u8fd9\u4e48\u505a\u4e86\u3002<\/p>\n
\u975e\u552f\u4e00\u7d22\u5f15\u4e0a\u5b58\u5728"\u7b49\u503c"\u7684\u4f8b\u5b50<\/h3>\n
\u63d2\u5165\u4e00\u884c\u6570\u636e<\/strong><\/p>\n
mysql> insert into t values(30,10,30);<\/code><\/pre>\n
\"MySQL\u52a0\u9501\u5b9e\u8df5-\u7d22\u5f15C\"<\/p>\n
session1\uff08\u7b2c\u4e00\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> begin;\nQuery OK, 0 rows affected (0.00 sec)\n\nmysql> delete from t where c=10;\nQuery OK, 2 rows affected (0.00 sec)<\/code><\/pre>\n
session2\uff08\u7b2c\u4e8c\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> insert into t values(12,12,12);\n(blocked)\nERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction<\/code><\/pre>\n
session3\uff08\u7b2c\u4e09\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> update t set d=d+1 where id=15;\nQuery OK, 1 row affected (0.00 sec)\nRows matched: 1  Changed: 1  Warnings: 0<\/code><\/pre>\n
\u5206\u6790\uff1a<\/p>\n
1\u3001session1 \u5728\u904d\u5386\u7684\u65f6\u5019\u9996\u5148\u8bbf\u95ee\u7b2c\u4e00\u4e2ac=10<\/code>\u7684\u8bb0\u5f55 \uff0c\u5bf9(c=5,id=5)<\/code>\u5230(c=10,id=10)<\/code>\u5de6\u5f00\u53f3\u95ed \u533a\u57df\u8bb0\u5f55\u52a0 next-key lock\u3002<\/p>\n
2\u3001session1 \u5411\u53f3\u67e5\u8be2\u7b2c\u4e8c\u4e2ac=10<\/code>\u7684\u8bb0\u5f55\uff0c\u627e\u5230(c=10,id=30)<\/code>\u8bb0\u5f55\u4e4b\u540e\u7ee7\u7eed\u5411\u53f3\u67e5\u627e\u76f4\u5230\u627e\u5230(c=15,id=15)<\/code>\u8fd9\u4e00\u884c\uff0c\u6839\u636e\u7b49\u503c\u67e5\u8be2\u4f18\u5316\uff0c\u627e\u5230\u7b2c\u4e00\u4e2a\u4e0d\u7b49\u503c\u7684\u8bb0\u5f55\u65f6\u9000\u5316\u4e3a(c=10,id=30)<\/code>\u5230(c=15,id=15)<\/code>\u5de6\u5f00\u53f3\u5f00\u95f4\u9699\u9501\uff0c(c=15,id=15)<\/code>\u8bb0\u5f55\u4e0d\u5305\u62ec\u533a\u57df\u8bb0\u5f55\u52a0 next-key lock\u3002<\/p>\n
\u52a0\u9501\u533a\u57df<\/strong><\/p>\n
\"MySQL\u52a0\u9501\u5b9e\u8df5-\u7d22\u5f15C\u52a0\u9501\u533a\u57df\"<\/p>\n
limit \u8bed\u53e5\u52a0\u9501<\/h3>\n
\u540c\u6837\u63d2\u5165\u4e00\u884c\u6570\u636e<\/strong><\/p>\n
mysql> insert into t values(30,10,30);\nQuery OK, 1 row affected (0.00 sec)<\/code><\/pre>\n
session1\uff08\u7b2c\u4e00\u4e2a\u4f1a\u8bdd\u4e0d\u52a0limit\uff09<\/strong><\/p>\n
mysql> begin;\nQuery OK, 0 rows affected (0.00 sec)\n\nmysql> delete from t where c=10;\nQuery OK, 2 row affected (0.00 sec)<\/code><\/pre>\n
session2\uff08\u7b2c\u4e8c\u4e2a\u4f1a\u8bdd\u4e0d\u52a0limit\uff09<\/strong><\/p>\n
mysql> insert into t values(12,12,12);\n(blocked)\nERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction<\/code><\/pre>\n
session1\uff08\u7b2c\u4e00\u4e2a\u4f1a\u8bdd\u52a0limit\uff09<\/strong><\/p>\n
mysql> begin;\nQuery OK, 0 rows affected (0.00 sec)\n\nmysql> delete from t where c=10 limit 2;\nQuery OK, 2 rows affected (0.00 sec)<\/code><\/pre>\n
session2\uff08\u7b2c\u4e8c\u4e2a\u4f1a\u8bdd\u52a0limit\uff09<\/strong><\/p>\n
mysql> insert into t values(12,12,12);\nQuery OK, 1 row affected (0.01 sec)<\/code><\/pre>\n
\"MySQL\u52a0\u9501\u5b9e\u8df5-\u52a0limit\u540e\u7d22\u5f15C\u52a0\u9501\u533a\u57df\"<\/p>\n
\u5206\u6790\uff1a<\/p>\n
1\u3001session 1 \u7684 delete \u8bed\u53e5\u52a0\u4e86limit 2<\/code>\u3002\u4f60\u77e5\u9053\u8868 t \u91ccc=10<\/code>\u7684\u8bb0\u5f55\u5176\u5b9e\u53ea\u6709\u4e24\u6761\uff0c\u56e0\u6b64\u52a0\u4e0d\u52a0limit 2<\/code>\uff0c\u5220\u9664\u7684\u6548\u679c\u90fd\u662f\u4e00\u6837\u7684\uff0c\u4f46\u662f\u52a0\u9501\u7684\u6548\u679c\u5374\u4e0d\u540c\u3002\u53ef\u4ee5\u770b\u5230\uff0csession 2 \u7684 insert \u8bed\u53e5\u6267\u884c\u901a\u8fc7\u4e86\u3002<\/p>\n
2\u3001delete \u8bed\u53e5\u660e\u786e\u52a0\u4e86limit 2<\/code>\u7684\u9650\u5236\uff0c\u56e0\u6b64\u5728\u904d\u5386\u5230(c=10,id=30)<\/code>\u8fd9\u4e00\u884c\u4e4b\u540e\uff0c\u6ee1\u8db3\u6761\u4ef6\u7684\u8bed\u53e5\u5df2\u7ecf\u6709\u4e24\u6761\uff0c\u5faa\u73af\u5c31\u7ed3\u675f\u4e86\u3002\u56e0\u6b64\uff0c\u7d22\u5f15 c \u4e0a\u7684\u52a0\u9501\u8303\u56f4\u5c31\u53d8\u6210\u4e86\u4ece(c=5,id=5)<\/code>\u5230(c=10,id=30)<\/code>\u8fd9\u4e2a\u524d\u5f00\u540e\u95ed\u533a\u95f4<\/p>\n
\u5728\u5220\u9664\u6570\u636e\u7684\u65f6\u5019\u5c3d\u91cf\u52a0 limit\u3002\u8fd9\u6837\u4e0d\u4ec5\u53ef\u4ee5\u63a7\u5236\u5220\u9664\u6570\u636e\u7684\u6761\u6570\uff0c\u8ba9\u64cd\u4f5c\u66f4\u5b89\u5168\uff0c\u8fd8\u53ef\u4ee5\u51cf\u5c0f\u52a0\u9501\u7684\u8303\u56f4<\/p>\n
\u4e00\u4e2a\u6b7b\u9501\u7684\u4f8b\u5b50<\/h3>\n
session1\uff08\u7b2c\u4e00\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> begin;\nQuery OK, 0 rows affected (0.00 sec)\n\nmysql> select id from t where c=10 lock in share mode;\n+----+\n| id |\n+----+\n| 10 |\n| 30 |\n+----+\n2 rows in set (0.00 sec)<\/code><\/pre>\n
session2\uff08\u7b2c\u4e8c\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> update t set d=d+1 where c=10;\n(blocked)<\/code><\/pre>\n
session1\uff08\u7b2c\u4e00\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
mysql> insert into t values(8,8,8);\nQuery OK, 1 row affected (0.00 sec)<\/code><\/pre>\n
session2\uff08\u7b2c\u4e8c\u4e2a\u4f1a\u8bdd\uff09<\/strong><\/p>\n
ERROR 1213 (40001): Deadlock found when trying to get lock; try restarting transaction<\/code><\/pre>\n
\u5206\u6790\uff1a<\/p>\n
1\u3001session A \u542f\u52a8\u4e8b\u52a1\u540e\u6267\u884c\u67e5\u8be2\u8bed\u53e5\u52a0 lock in share mode\uff0c\u5728\u7d22\u5f15 c \u4e0a\u52a0\u4e86 next-key lock (5, 10]<\/code>\u548c\u95f4\u9699\u9501(10, 15)<\/code><\/p>\n
2\u3001session B \u7684 update \u8bed\u53e5\u4e5f\u8981\u5728\u7d22\u5f15 c \u4e0a\u52a0 next-key lock (5, 10]<\/code>\uff0c\u8fdb\u5165\u9501\u7b49\u5f85<\/p>\n
3\u3001\u7136\u540e session A \u8981\u518d\u63d2\u5165(8,8,8)<\/code>\u8fd9\u4e00\u884c\uff0c\u88ab session B \u7684\u95f4\u9699\u9501\u9501\u4f4f\u3002\u7531\u4e8e\u51fa\u73b0\u4e86\u6b7b\u9501\uff0cInnoDB \u8ba9 session B \u56de\u6eda\u3002<\/p>\n
\u4f60\u53ef\u80fd\u4f1a\u95ee\uff0csession B \u7684 next-key lock \u4e0d\u662f\u8fd8\u6ca1\u7533\u8bf7\u6210\u529f\u5417\uff1f\u5176\u5b9e\u662f\u8fd9\u6837\u7684\uff0csession B \u7684\u201c\u52a0 next-key lock (5, 10] \u201d\u64cd\u4f5c\uff0c\u5b9e\u9645\u4e0a\u5206\u6210\u4e86\u4e24\u6b65\uff0c\u5148\u662f\u52a0(5, 10)<\/code>\u7684\u95f4\u9699\u9501\uff0c\u52a0\u9501\u6210\u529f\uff1b\u7136\u540e\u52a0c=10<\/code>\u7684\u884c\u9501\uff0c\u8fd9\u65f6\u5019\u624d\u88ab\u9501\u4f4f\u7684\u3002\u4e5f\u5c31\u662f\u8bf4\uff0c\u6211\u4eec\u5728\u5206\u6790\u52a0\u9501\u89c4\u5219\u7684\u65f6\u5019\u53ef\u4ee5\u7528 next-key lock \u6765\u5206\u6790\u3002\u4f46\u662f\u8981\u77e5\u9053\uff0c\u5177\u4f53\u6267\u884c\u7684\u65f6\u5019\uff0c\u662f\u8981\u5206\u6210\u95f4\u9699\u9501\u548c\u884c\u9501\u4e24\u6bb5\u6765\u6267\u884c\u7684\u3002<\/p>\n
\u603b\u7ed3\u4e0b\u6765\uff0c\u53ef\u91cd\u590d\u8bfb\u9694\u79bb\u7ea7\u522b\u9075\u5b88\u4e24\u9636\u6bb5\u534f\u8bae\uff0c\u6240\u6709\u7684\u9501\u90fd\u5728\u4e8b\u52a1\u63d0\u4ea4\u6216\u8005\u56de\u6eda\u624d\u91ca\u653e\uff1bread-commited<\/code>\u6ca1\u6709gap lock \uff0cread-commited<\/code>\u8bed\u53e5\u6267\u884c\u5b8c\u5c31\u91ca\u653e\u201c\u4e0d\u6ee1\u8db3\u6761\u4ef6\u7684\u884c\u201d\u7684\u884c\u9501\uff0c\u800c\u4e0d\u662f\u5728\u4e8b\u52a1\u7ed3\u675f\u7684\u65f6\u5019\u624d\u91ca\u653e\u3002\u603b\u7ed3\u6765\u8bf4\uff0c\u8bfb\u63d0\u4ea4\u9694\u79bb\u7ea7\u522b\u4e0b\uff0c\u9501\u7684\u8303\u56f4\u66f4\u5c0f\uff0c\u9501\u7684\u65f6\u95f4\u66f4\u77ed\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u95f4\u9699\u9501\uff08Gap Lock\uff09 \u9996\u5148\u8c08\u8c08\u95f4\u9699\u9501\u662f\u4ec0\u4e48\u3002 \u95f4\u9699\u9501\u662f\u4e13\u95e8\u7528\u4e8e\u89e3\u51b3\u5e7b\u8bfb\u8fd9\u79cd\u95ee\u9898\u7684\u9501\uff0c\u5b83\u9501\u7684\u4e86\u884c\u4e0e\u884c\u4e4b\u95f4\u7684 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[13],"tags":[],"class_list":["post-2089","post","type-post","status-publish","format-standard","hentry","category-mysql"],"_links":{"self":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/posts\/2089","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/comments?post=2089"}],"version-history":[{"count":0,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/posts\/2089\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/media?parent=2089"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/categories?post=2089"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.appblog.cn\/index.php\/wp-json\/wp\/v2\/tags?post=2089"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}