Mysql 死锁问题（一）

show engine innodb status\G

*** (1) TRANSACTION:
TRANSACTION 8631FDC, ACTIVE 0 sec inserting
mysql tables in use 2, locked 2
LOCK WAIT 7 lock struct(s), heap size 1248, 107 row lock(s)
MySQL thread id 28162, OS thread handle 0x7f4ab3073700, query id 210340529 tc-demo-dev3.dfengg.com 172.16.2.173 root
INSERT INTO Text****(BusinessId,Type,Template,CreatedUserId,LastModifiedUserId,Delivery,DeliveryWindow,BusinessCalendar) SELECT 124001698, 205, '[CustomerFirstName], your next appointment with [Business] is [AppointmentDateTime]. We look forward to seeing you at your upcoming appointment.', 0, 0, IFNULL(96, Delivery),DeliveryWindow,BusinessCalendar FROM Text**** WHERE BusinessId=0 AND Type=205
*** (1) WAITING FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 794567 page no 6 n bits 88 index `PRIMARY` of table `df1`.`Text****` trx id 8631FDC lock_mode X insert intention waiting
Record lock, heap no 1 PHYSICAL RECORD: n_fields 1; compact format; info bits 0
 0: len 8; hex 73757072656d756d; asc supremum;;

*** (2) TRANSACTION:
TRANSACTION 8631FDB, ACTIVE 0 sec setting auto-inc lock
mysql tables in use 2, locked 2
5 lock struct(s), heap size 1248, 106 row lock(s)
MySQL thread id 28158, OS thread handle 0x7f4a48cd0700, query id 210340528 tc-demo-dev3.dfengg.com 172.16.2.173 root
INSERT INTO Text****(BusinessId,Type,Template,CreatedUserId,LastModifiedUserId,Delivery,DeliveryWindow,BusinessCalendar) SELECT 124001699, 406, 'Dear [CustomerFirstName],\n\nYou have an upcoming appointment with [BusinessName]. Please take a minute to review the details of your appointment scheduled for:\n\n[AppointmentDateTime]\n\nIf you are unable to make this appointment, it is important that you call us at [BusinessPhone] as soon as possible so we can make other arrangements.\n\nWe look forward to seeing you at your upcoming appointment.\n\nSincerely,\n\n[BusinessName]\n[BusinessPhone]\n[BusinessEmail]\n[BusinessWebsite]\n\n-----\nThis email provided by Demandforce, Inc. To unsubscribe, please click this link:\n\n[UnsubscribeLink]\n\n', 0, 0, IFNULL(504, Delivery),DeliveryWindow,BusinessCalendar FROM Text**** WHERE BusinessId=0 AND Type=406
*** (2) HOLDS THE LOCK(S):
RECORD LOCKS space id 794567 page no 6 n bits 88 index `PRIMARY` of table `df1`.`Text****` trx id 8631FDB lock mode S
Record lock, heap no 1 PHYSICAL RECORD: n_fields 1; compact format; info bits 0

.................................

*** (2) WAITING FOR THIS LOCK TO BE GRANTED:
TABLE LOCK table `df1`.`Text****` trx id 8631FDB lock mode AUTO-INC waiting
*** WE ROLL BACK TRANSACTION (2)

分析：

1）insert .... select ...语句，在MYSQL里，会对select ...涉及的所有记录进行锁定，这是特殊的select加X锁的情况，原因是为保证数据的一致性（M-S环境），假设不锁定，在执行过程中，select包含的表一直在做插入操作，那么M端select出来的记录数就会比S端少，数据就会不一致。

 

2）查看select的执行计划

mysql> explain SELECT 124001698, 205, '[CustomerFirstName], your next appointment with [Business] is [AppointmentDateTime]. We look forward to seeing you at your upcoming appointment.', 0, 0, IFNULL(96, Delivery),DeliveryWindow,BusinessCalendar FROM Text**** WHERE BusinessId=0 AND Type=205;
+----+-------------+---------------------+------+---------------+------+---------+------+------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+---------------------+------+---------------+------+---------+------+------+-------------+
| 1 | SIMPLE | Text**** | ALL | NULL | NULL | NULL | NULL | 6108 | Using where |
+----+-------------+---------------------+------+---------------+------+---------+------+------+-------------+
1 row in set (0.00 sec)

key=null,rows=6108

全表扫描，没有可用的索引。

 

解决办法：

在BusinessId,Type字段建复合索引。

 

通过索引1）可以更快的定位数据2）锁定更少的行。