问题描述：
数据库从库停止同步。
问题分析：
show slave statusG;（也可使用show full processlist）
显示 某个update语句出错，Lock wait timeout exceeded; try restarting transaction;
原因是这条语句提交的时候超时堵塞。原因在于另外的一个操作开启了事务，锁定了相应的数据，导致这条操作相同数据的sql出错。
示例，在sql中
（1）开启事务，锁定数据
终端A：
mysql> begin; (开启事务，开启事务会锁定相关数据)
Query OK, 0 rows affected (0.00 sec)
mysql> update pet set sex="m" where name="Fluffy";（修改）
Query OK, 1 row affected (0.03 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from pet;
+--------+--------+---------+------+------------+------------+
| name | owner | species | sex | birth | death |
+--------+--------+---------+------+------------+------------+
| Bowser | Diane | dog | m | 1979-08-31 | 1995-07-29 |
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
| Claws | Gwen | cat | m | 1994-03-17 | NULL |
| Fang | Benny | dog | m | 2013-02-05 | NULL |
| Fluffy | Harold | cat | m | 2012-09-30 | NULL |
+--------+--------+---------+------+------------+------------+
5 rows in set (0.00 sec)
终端B：
mysql> select * from pet;
+--------+--------+---------+------+------------+------------+
| name | owner | species | sex | birth | death |
+--------+--------+---------+------+------------+------------+
| Bowser | Diane | dog | m | 1979-08-31 | 1995-07-29 |
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
| Claws | Gwen | cat | m | 1994-03-17 | NULL |
| Fang | Benny | dog | m | 2013-02-05 | NULL |
| Fluffy | Harold | cat | NULL | 2012-09-30 | NULL |
+--------+--------+---------+------+------------+------------+
5 rows in set (0.01 sec)
因为没有提交，所以实际上没有改变。但是会锁定Fluffy这一条数据。导致如下的错误。
终端B：
mysql> update pet set sex="m" where name="Fluffy";
ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction
（2）提交事务，解锁数据
终端A：
mysql> commit;
Query OK, 0 rows affected (0.10 sec)
终端B：
mysql> select * from pet;
+--------+--------+---------+------+------------+------------+
| name | owner | species | sex | birth | death |
+--------+--------+---------+------+------------+------------+
| Bowser | Diane | dog | m | 1979-08-31 | 1995-07-29 |
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
| Claws | Gwen | cat | m | 1994-03-17 | NULL |
| Fang | Benny | dog | m | 2013-02-05 | NULL |
| Fluffy | Harold | cat | m | 2012-09-30 | NULL |
+--------+--------+---------+------+------------+------------+
5 rows in set (0.00 sec)
mysql> update pet set sex="f" where name="Fluffy";
Query OK, 1 row affected (0.08 sec)
Rows matched: 1 Changed: 1 Warnings: 0
（3）如果where中的条件是索引字段，那么只会锁定索引对应的条目；如果不是索引字段，那么会锁定整张表。
终端A：
mysql> update pet set sex="f" where death="1995-07-29";
Query OK, 1 row affected (0.03 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from pet;
+--------+--------+---------+------+------------+------------+
| name | owner | species | sex | birth | death |
+--------+--------+---------+------+------------+------------+
| Bowser | Diane | dog | f | 1979-08-31 | 1995-07-29 |
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
| Claws | Gwen | cat | m | 1994-03-17 | NULL |
| Fang | Benny | dog | m | 2013-02-05 | NULL |
| Fluffy | Harold | cat | f | 2012-09-30 | NULL |
+--------+--------+---------+------+------------+------------+
5 rows in set (0.00 sec)
终端B：
mysql> select * from pet;
+--------+--------+---------+------+------------+------------+
| name | owner | species | sex | birth | death |
+--------+--------+---------+------+------------+------------+
| Bowser | Diane | dog | m | 1979-08-31 | 1995-07-29 |
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
| Claws | Gwen | cat | m | 1994-03-17 | NULL |
| Fang | Benny | dog | m | 2013-02-05 | NULL |
| Fluffy | Harold | cat | f | 2012-09-30 | NULL |
+--------+--------+---------+------+------------+------------+
5 rows in set (0.00 sec)
mysql> update pet set death="2013-07-00" where birth="2013-02-05";
ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction
解决办法
（1） stop slave; start slave
(2)网上分析说
Mysql 'Lock wait timeout exceeded; try restarting transaction' 解决方案
ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction
Temporary error: 266: Time-out in NDB, probably caused by deadlock 解决方法：在管理节点的[ndbd default]
区加：
TransactionDeadLockDetectionTimeOut=10000（设置为10秒）默认是1200（1.2秒）按照顺序重新启动各个节点就不会出现问题了。