标签：ack 申请 b16 type 会同 互斥 engine 一个 l数据库
CREATE TABLE `test` ( `id` bigint(11) NOT NULL , `name` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL , `type` tinyint(4) NULL DEFAULT NULL , `uid` int(11) NULL DEFAULT NULL , PRIMARY KEY (`id`), UNIQUE INDEX `uniq_type_name` (`type`, `name`) USING BTREE ) ENGINE=InnoDB DEFAULT CHARACTER SET=utf8 COLLATE=utf8_general_ci ROW_FORMAT=COMPACT ;
insert into test(id, name, type, uid) values(1, "DT590", 3, 1001); insert into test(id, name, type, uid) values(2, "DT589", 3, 1001); insert into test(id, name, type, uid) values(3, "DT588", 3, 1001);
------------------------ LATEST DETECTED DEADLOCK ------------------------ 2018-06-21 10:51:03 2b16deb03700 *** (1) TRANSACTION: TRANSACTION 1905650677, ACTIVE 0.001 sec inserting mysql tables in use 1, locked 1 LOCK WAIT 2 lock struct(s), heap size 360, 1 row lock(s), undo log entries 1 LOCK BLOCKING MySQL thread id: 16983306 block 34208692 MySQL thread id 34208692, OS thread handle 0x2b2203b0b700, query id 9093982364 172.24.18.106 app_redcliffc update INSERT INTO `test` (id, name, type, uid) VALUES (4, ‘DT590‘, 3, 1001) *** (1) WAITING FOR THIS LOCK TO BE GRANTED: RECORD LOCKS space id 138 page no 16492 n bits 408 index `uniq_type_name` of table `db`.`test` trx id 1905650677 lock mode S waiting Record lock, heap no 341 PHYSICAL RECORD: n_fields 3; compact format; info bits 0 0: len 4; hex 80000048; asc H;; 1: len 10; hex 44543631393230363835; asc DT61920685;; 2: len 8; hex 0461116807c09a00; asc a h ;; *** (2) TRANSACTION: TRANSACTION 1905650675, ACTIVE 0.004 sec inserting mysql tables in use 1, locked 1 3 lock struct(s), heap size 1184, 2 row lock(s), undo log entries 2 MySQL thread id 16983306, OS thread handle 0x2b16deb03700, query id 9093982366 172.24.18.105 app_redcliffc update INSERT INTO `test` (id, name, type, uid) VALUES (2, ‘DT589‘, 3, 1001) *** (2) HOLDS THE LOCK(S): RECORD LOCKS space id 138 page no 16492 n bits 408 index `uniq_type_name` of table `db`.`test` trx id 1905650675 lock_mode X locks rec but not gap Record lock, heap no 341 PHYSICAL RECORD: n_fields 3; compact format; info bits 0 0: len 4; hex 80000048; asc H;; 1: len 10; hex 44543631393230363835; asc DT61920685;; 2: len 8; hex 0461116807c09a00; asc a h ;; *** (2) WAITING FOR THIS LOCK TO BE GRANTED: RECORD LOCKS space id 138 page no 16492 n bits 408 index `uniq_type_name` of table `db`.`test` trx id 1905650675 lock_mode X locks gap before rec insert intention waiting Record lock, heap no 341 PHYSICAL RECORD: n_fields 3; compact format; info bits 0 0: len 4; hex 80000048; asc H;; 1: len 10; hex 44543631393230363835; asc DT61920685;; 2: len 8; hex 0461116807c09a00; asc a h ;; *** WE ROLL BACK TRANSACTION (1)
| session1 | session2 | |
| insert into test(id, name, type, uid) values(1, "DT590", 3, 1001); | 事务一先到，先插入第一条记录DT590，成功 | |
| insert into test(id, name, type, uid) values(2, "DT589", 3, 1001); |
事务一继续插入第二天DT589记录，这个时候事务二请求到了，开始
插入第一条记录DT590，然后就报出死锁，事务二回滚，事务一成功执行
|
insert into test(id, name, type, uid) values(1, "DT590", 3, 1001); |
| session1 | 持锁 | session2 | 持锁 |
| insert into test(id, name, type, uid) values(1, "DT590", 3, 1001); | 插入一条数据库中没有的记录，对DT590这条记录加了一个x锁 | ||
| insert into test(id, name, type, uid) values(2, "DT589", 3, 1001); |
这时事务一插入DT589时候，发现这条记录已经有了一个gap lock（DT589这条记录刚好被事务二插DT590时候申请的gap lock包含了），会先申请一个insert intention waiting插入意向锁，这个锁和事务二持有gap lock互斥，发生死锁。
事务一在等事务二释放这条记录gap lock， 事务二在等事务一释放DT590 X锁
|
insert into test(id, name, type, uid) values(1, "DT590", 3, 1001); | 事务二插入有唯一索引DT590这条记录，发现这条记录上已经有了x锁，所以会申请一个该条记录的s锁和gap lock |
标签：ack 申请 b16 type 会同 互斥 engine 一个 l数据库
原文地址：https://www.cnblogs.com/lylife/p/9231818.html
