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如何理解MYSQL RC模式insert update可能死锁的情况

发表于：2024-11-19 作者：千家信息网编辑

千家信息网最后更新 2024年11月19日，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

千家信息网最后更新 2024年11月19日如何理解MYSQL RC模式insert update可能死锁的情况

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

---TRANSACTION 322809, ACTIVE 30 sec starting index read
mysql tables in use 1, locked 1
3 lock struct(s), heap size 1160, 2 row lock(s), undo log entries 1
MySQL thread id 3, OS thread handle 140734663714560, query id 409 localhost root updating
update testlll set name='gaopeng1' where id=24
---lock strcut(1):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx
TABLE LOCK table `test`.`testlll` trx id 322809 lock mode IX
---lock strcut(2):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx
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)
Record lock, heap no 25 PHYSICAL RECORD: n_fields 4; compact format; info bits 0
0: len 4; hex 80000019; asc ;;
1: len 6; hex 00000004ecf9; asc ;;
2: len 7; hex f0000001f90110; asc ;;
3: len 7; hex 67616f70656e67; asc gaopeng;;
---lock strcut(3):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx
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)
Record lock, heap no 20 PHYSICAL RECORD: n_fields 4; compact format; info bits 0
0: len 4; hex 80000018; asc ;;
1: len 6; hex 00000004ecf8; asc ;;
2: len 7; hex ef000001f80110; asc ;;
3: len 7; hex 67616f70656e67; asc gaopeng;;
---TRANSACTION 322808, ACTIVE 43 sec starting index read
mysql tables in use 1, locked 1
LOCK WAIT 3 lock struct(s), heap size 1160, 2 row lock(s), undo log entries 1
MySQL thread id 2, OS thread handle 140734663980800, query id 408 localhost root updating
update testlll set name='gaopeng1' where id=25
------- TRX HAS BEEN WAITING 5 SEC FOR THIS LOCK TO BE GRANTED:
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)
Record lock, heap no 25 PHYSICAL RECORD: n_fields 4; compact format; info bits 0
0: len 4; hex 80000019; asc ;;
1: len 6; hex 00000004ecf9; asc ;;
2: len 7; hex f0000001f90110; asc ;;
3: len 7; hex 67616f70656e67; asc gaopeng;;

------------------
---lock strcut(1):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx
TABLE LOCK table `test`.`testlll` trx id 322808 lock mode IX
---lock strcut(2):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx
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)
Record lock, heap no 25 PHYSICAL RECORD: n_fields 4; compact format; info bits 0
0: len 4; hex 80000019; asc ;;
1: len 6; hex 00000004ecf9; asc ;;
2: len 7; hex f0000001f90110; asc ;;
3: len 7; hex 67616f70656e67; asc gaopeng;;
---lock strcut(3):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx
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)
Record lock, heap no 20 PHYSICAL RECORD: n_fields 4; compact format; info bits 0
0: len 4; hex 80000018; asc ;;
1: len 6; hex 00000004ecf8; asc ;;
2: len 7; hex ef000001f80110; asc ;;
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

---TRANSACTION 422212176315800, not started
0 lock struct(s), heap size 1160, 0 row lock(s)
---TRANSACTION 323284, ACTIVE 10 sec inserting
mysql tables in use 1, locked 1
3 lock struct(s), heap size 1160, 2 row lock(s), undo log entries 1
MySQL thread id 2, OS thread handle 140734663980800, query id 369 localhost root update
insert into testlll values(26,'gaopeng')
---lock strcut(1):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx
TABLE LOCK table `test`.`testlll` trx id 323284 lock mode IX
---lock strcut(2):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx
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)
Record lock, heap no 27 PHYSICAL RECORD: n_fields 4; compact format; info bits 0
0: len 4; hex 8000001b; asc ;;
1: len 6; hex 00000004eed4; asc ;;
2: len 7; hex d3000002a10110; asc ;;
3: len 7; hex 67616f70656e67; asc gaopeng;;
---lock strcut(3):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx
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)
Record lock, heap no 26 PHYSICAL RECORD: n_fields 4; compact format; info bits 0
0: len 4; hex 8000001a; asc ;;
1: len 6; hex 00000004eed3; asc ;;
2: len 7; hex d2000002330110; asc 3 ;;
3: len 7; hex 67616f70656e67; asc gaopeng;;
---TRANSACTION 323283, ACTIVE 14 sec inserting
mysql tables in use 1, locked 1
LOCK WAIT 3 lock struct(s), heap size 1160, 2 row lock(s), undo log entries 1
MySQL thread id 3, OS thread handle 140734663714560, query id 368 localhost root update
insert into testlll values(27,'gaopeng')
------- TRX HAS BEEN WAITING 5 SEC FOR THIS LOCK TO BE GRANTED:
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)
Record lock, heap no 27 PHYSICAL RECORD: n_fields 4; compact format; info bits 0
0: len 4; hex 8000001b; asc ;;
1: len 6; hex 00000004eed4; asc ;;
2: len 7; hex d3000002a10110; asc ;;
3: len 7; hex 67616f70656e67; asc gaopeng;;
------------------
---lock strcut(1):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx
TABLE LOCK table `test`.`testlll` trx id 323283 lock mode IX
---lock strcut(2):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx
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)
Record lock, heap no 27 PHYSICAL RECORD: n_fields 4; compact format; info bits 0
0: len 4; hex 8000001b; asc ;;
1: len 6; hex 00000004eed4; asc ;;
2: len 7; hex d3000002a10110; asc ;;
3: len 7; hex 67616f70656e67; asc gaopeng;;
---lock strcut(3):(Add by gaopeng) In modify Version I force check all REC_LOCK/TAB_LOCK for this Trx
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)
Record lock, heap no 26 PHYSICAL RECORD: n_fields 4; compact format; info bits 0
0: len 4; hex 8000001a; asc ;;
1: len 6; hex 00000004eed3; asc ;;
2: len 7; hex d2000002330110; asc 3 ;;
3: len 7; hex 67616f70656e67; asc gaopeng;;