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如何理解MYSQL RC模式insert update可能死锁的情况

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本篇文章给大家分享的是有关如何理解MYSQL RC模式insert update可能死锁的情况，小编觉得挺实用的，因此分享给大家学习，希望大家阅读完这篇文章后可以有所收获，话不多说，跟着小编一起来看看吧。

涉及的语句为
RC模式下
update根据主键更新和insert
其实这样的问题在RC模式下，要么是简单update问题，要么是insert造成的主键和唯一键检查唯一性时出现问题。
下面以主键问题为列子进行分析一下可能出现的情况。

update  where条件更新为主键，锁结构出现在单行主键上，辅助索引包含隐含锁结构，当前读RC非唯一索引模式没有GAP锁，
insert  插入印象锁，主键和辅助索引上会出现隐含锁结构，

但是在RC模式下没有GAP所以插入印象锁一般不会成为问题

表结构：
+———+———————————————————————————————————————————————————————————–+
| Table   | Create Table                                                                                                                                                                      |
+———+———————————————————————————————————————————————————————————–+
| testlll | CREATE TABLE `testlll` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(20) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=24 DEFAULT CHARSET=latin1 |
+———+———————————————————————————————————————————————————————————–+

情况1
insert
update

TX1：                                                                  TX2：
insert into testlll(name) values('gaopeng');
                                                                          insert into testlll(name) values('gaopeng');
update testlll set name='gaopeng1' where id=25;(堵塞)
                                                                           update testlll set name='gaopeng1' where id=24;(堵塞)
                                               
死锁

锁结构：

点击(此处)折叠或打开

  1. —TRANSACTION 322809, ACTIVE 30 sec starting index read

  2. mysql tables in use 1, locked 1

  3. 3 lock struct(s), heap size 1160, 2 row lock(s), undo log entries 1

  4. MySQL thread id 3, OS thread handle 140734663714560, query id 409 localhost root updating

  5. update testlll set name='gaopeng1' where id=24

  6. —lock strcut(1):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx

  7. TABLE LOCK table `test`.`testlll` trx id 322809 lock mode IX

  8. —lock strcut(2):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx

  9. RECORD LOCKS space id 434 page no 3 n bits 96 index PRIMARY of table `test`.`testlll` trx id 322809 lock_mode X(LOCK_X) locks rec but not gap(LOCK_REC_NOT_GAP)

  10. Record lock, heap no 25 PHYSICAL RECORD: n_fields 4; compact format; info bits 0

  11.  0: len 4; hex 80000019; asc ;;

  12.  1: len 6; hex 00000004ecf9; asc ;;

  13.  2: len 7; hex f0000001f90110; asc ;;

  14.  3: len 7; hex 67616f70656e67; asc gaopeng;;

  15. —lock strcut(3):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx

  16. RECORD LOCKS space id 434 page no 3 n bits 96 index PRIMARY of table `test`.`testlll` trx id 322809 lock_mode X(LOCK_X) locks rec but not gap(LOCK_REC_NOT_GAP) waiting(LOCK_WAIT)

  17. Record lock, heap no 20 PHYSICAL RECORD: n_fields 4; compact format; info bits 0

  18.  0: len 4; hex 80000018; asc ;;

  19.  1: len 6; hex 00000004ecf8; asc ;;

  20.  2: len 7; hex ef000001f80110; asc ;;

  21.  3: len 7; hex 67616f70656e67; asc gaopeng;;

  22. —TRANSACTION 322808, ACTIVE 43 sec starting index read

  23. mysql tables in use 1, locked 1

  24. LOCK WAIT 3 lock struct(s), heap size 1160, 2 row lock(s), undo log entries 1

  25. MySQL thread id 2, OS thread handle 140734663980800, query id 408 localhost root updating

  26. update testlll set name='gaopeng1' where id=25

  27. ——- TRX HAS BEEN WAITING 5 SEC FOR THIS LOCK TO BE GRANTED:

  28. RECORD LOCKS space id 434 page no 3 n bits 96 index PRIMARY of table `test`.`testlll` trx id 322808 lock_mode X(LOCK_X) locks rec but not gap(LOCK_REC_NOT_GAP) waiting(LOCK_WAIT)

  29. Record lock, heap no 25 PHYSICAL RECORD: n_fields 4; compact format; info bits 0

  30.  0: len 4; hex 80000019; asc ;;

  31.  1: len 6; hex 00000004ecf9; asc ;;

  32.  2: len 7; hex f0000001f90110; asc ;;

  33.  3: len 7; hex 67616f70656e67; asc gaopeng;;

    ——————

  34. —lock strcut(1):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx

  35. TABLE LOCK table `test`.`testlll` trx id 322808 lock mode IX

  36. —lock strcut(2):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx

  37. RECORD LOCKS space id 434 page no 3 n bits 96 index PRIMARY of table `test`.`testlll` trx id 322808 lock_mode X(LOCK_X) locks rec but not gap(LOCK_REC_NOT_GAP) waiting(LOCK_WAIT)

  38. Record lock, heap no 25 PHYSICAL RECORD: n_fields 4; compact format; info bits 0

  39.  0: len 4; hex 80000019; asc ;;

  40.  1: len 6; hex 00000004ecf9; asc ;;

  41.  2: len 7; hex f0000001f90110; asc ;;

  42.  3: len 7; hex 67616f70656e67; asc gaopeng;;

  43. —lock strcut(3):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx

  44. RECORD LOCKS space id 434 page no 3 n bits 96 index PRIMARY of table `test`.`testlll` trx id 322808 lock_mode X(LOCK_X) locks rec but not gap(LOCK_REC_NOT_GAP)

  45. Record lock, heap no 20 PHYSICAL RECORD: n_fields 4; compact format; info bits 0

  46.  0: len 4; hex 80000018; asc ;;

  47.  1: len 6; hex 00000004ecf8; asc ;;

  48.  2: len 7; hex ef000001f80110; asc ;;

  49.  3: len 7; hex 67616f70656e67; asc gaopeng;;

情况2
update
update

TX1：                                                                    TX2：
update testlll set name='gaopeng1' where id=22;
                                                                            update testlll set name='gaopeng1' where id=25;
update testlll set name='gaopeng1' where id=25;(堵塞)
                                                                             update testlll set name='gaopeng1' where id=22;(堵塞)
死锁

这种情况比较简单不打印出锁结构

情况3
insert
insert

TX1：                                                      TX2:
insert into testlll values(26,'gaopeng');
                                                             insert into testlll values(27,'gaopeng');
nsert into testlll values(27,'gaopeng');(堵塞)
                                                             insert into testlll values(26,'gaopeng');(堵塞)

死锁

锁结构:

点击(此处)折叠或打开

  1. —TRANSACTION 422212176315800, not started

  2. 0 lock struct(s), heap size 1160, 0 row lock(s)

  3. —TRANSACTION 323284, ACTIVE 10 sec inserting

  4. mysql tables in use 1, locked 1

  5. 3 lock struct(s), heap size 1160, 2 row lock(s), undo log entries 1

  6. MySQL thread id 2, OS thread handle 140734663980800, query id 369 localhost root update

  7. insert into testlll values(26,'gaopeng')

  8. —lock strcut(1):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx

  9. TABLE LOCK table `test`.`testlll` trx id 323284 lock mode IX

  10. —lock strcut(2):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx

  11. RECORD LOCKS space id 434 page no 3 n bits 96 index PRIMARY of table `test`.`testlll` trx id 323284 lock_mode X(LOCK_X) locks rec but not gap(LOCK_REC_NOT_GAP)

  12. Record lock, heap no 27 PHYSICAL RECORD: n_fields 4; compact format; info bits 0

  13.  0: len 4; hex 8000001b; asc ;;

  14.  1: len 6; hex 00000004eed4; asc ;;

  15.  2: len 7; hex d3000002a10110; asc ;;

  16.  3: len 7; hex 67616f70656e67; asc gaopeng;;

  17. —lock strcut(3):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx

  18. RECORD LOCKS space id 434 page no 3 n bits 96 index PRIMARY of table `test`.`testlll` trx id 323284 lock mode S(LOCK_S) locks rec but not gap(LOCK_REC_NOT_GAP) waiting(LOCK_WAIT)

  19. Record lock, heap no 26 PHYSICAL RECORD: n_fields 4; compact format; info bits 0

  20.  0: len 4; hex 8000001a; asc ;;

  21.  1: len 6; hex 00000004eed3; asc ;;

  22.  2: len 7; hex d2000002330110; asc 3 ;;

  23.  3: len 7; hex 67616f70656e67; asc gaopeng;;

  24. —TRANSACTION 323283, ACTIVE 14 sec inserting

  25. mysql tables in use 1, locked 1

  26. LOCK WAIT 3 lock struct(s), heap size 1160, 2 row lock(s), undo log entries 1

  27. MySQL thread id 3, OS thread handle 140734663714560, query id 368 localhost root update

  28. insert into testlll values(27,'gaopeng')

  29. ——- TRX HAS BEEN WAITING 5 SEC FOR THIS LOCK TO BE GRANTED:

  30. RECORD LOCKS space id 434 page no 3 n bits 96 index PRIMARY of table `test`.`testlll` trx id 323283 lock mode S(LOCK_S) locks rec but not gap(LOCK_REC_NOT_GAP) waiting(LOCK_WAIT)

  31. Record lock, heap no 27 PHYSICAL RECORD: n_fields 4; compact format; info bits 0

  32.  0: len 4; hex 8000001b; asc ;;

  33.  1: len 6; hex 00000004eed4; asc ;;

  34.  2: len 7; hex d3000002a10110; asc ;;

  35.  3: len 7; hex 67616f70656e67; asc gaopeng;;

    ——————

  36. —lock strcut(1):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx

  37. TABLE LOCK table `test`.`testlll` trx id 323283 lock mode IX

  38. —lock strcut(2):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx

  39. RECORD LOCKS space id 434 page no 3 n bits 96 index PRIMARY of table `test`.`testlll` trx id 323283 lock mode S(LOCK_S) locks rec but not gap(LOCK_REC_NOT_GAP) waiting(LOCK_WAIT)

  40. Record lock, heap no 27 PHYSICAL RECORD: n_fields 4; compact format; info bits 0

  41.  0: len 4; hex 8000001b; asc ;;

  42.  1: len 6; hex 00000004eed4; asc ;;

  43.  2: len 7; hex d3000002a10110; asc ;;

  44.  3: len 7; hex 67616f70656e67; asc gaopeng;;

  45. —lock strcut(3):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx

  46. RECORD LOCKS space id 434 page no 3 n bits 96 index PRIMARY of table `test`.`testlll` trx id 323283 lock_mode X(LOCK_X) locks rec but not gap(LOCK_REC_NOT_GAP)

  47. Record lock, heap no 26 PHYSICAL RECORD: n_fields 4; compact format; info bits 0

  48.  0: len 4; hex 8000001a; asc ;;

  49.  1: len 6; hex 00000004eed3; asc ;;

  50.  2: len 7; hex d2000002330110; asc 3 ;;

  51.  3: len 7; hex 67616f70656e67; asc gaopeng;;

以上就是如何理解MYSQL RC模式insert update可能死锁的情况，小编相信有部分知识点可能是我们日常工作会见到或用到的。希望你能通过这篇文章学到更多知识。更多详情敬请关注亿速云行业资讯频道。

原创文章，作者：kirin，如若转载，请注明出处：https://blog.ytso.com/204251.html

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