1205 - Lock wait timeout exceeded; try restarting transaction
解决：
select * from information_schema.innodb_trx; -- 找到了那个一直没有提交的只读事务 kill thread id; -- 对应的线程后
MySQL 5.5 – innodb_lock_wait 锁 等待
以前，当出现：ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction，
要解决是一件麻烦的事情 ；
特别是当一个SQL执行完了，但未COMMIT，后面的SQL想要执行就是被锁，超时结束；
DBA光从数据库无法着手找出源头是哪个SQL锁住了；
有时候看看
show engine innodb status, 并结合show full processlist;能暂时解决问题；但一直不能精确定位；
在5.5中，information_schema 库中增加了三个关于锁的表（MEMORY引擎）；
innodb_trx ## 当前运行的所有事务 innodb_locks ## 当前出现的锁 innodb_lock_waits ## 锁等待的对应关系
来看一下表结构
desc information_schema .innodb_locks; +-------------+---------------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------+---------------------+------+-----+---------+-------+ | lock_id | varchar(81) | NO | | | |#锁ID | lock_trx_id | varchar(18) | NO | | | |#拥有锁的事务ID | lock_mode | varchar(32) | NO | | | |#锁模式 | lock_type | varchar(32) | NO | | | |#锁类型 | lock_table | varchar(1024) | NO | | | |#被锁的表 | lock_index | varchar(1024) | YES | | NULL | |#被锁的索引 | lock_space | bigint(21) unsigned | YES | | NULL | |#被锁的表空间号 | lock_page | bigint(21) unsigned | YES | | NULL | |#被锁的页号 | lock_rec | bigint(21) unsigned | YES | | NULL | |#被锁的记录号 | lock_data | varchar(8192) | YES | | NULL | |#被锁的数据 +-------------+---------------------+------+-----+---------+-------+ desc information_schema .innodb_lock_waits; +-------------------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------------+-------------+------+-----+---------+-------+ | requesting_trx_id | varchar(18) | NO | | | |#请求锁的事务ID | requested_lock_id | varchar(81) | NO | | | |#请求锁的锁ID | blocking_trx_id | varchar(18) | NO | | | |#当前拥有锁的事务ID | blocking_lock_id | varchar(81) | NO | | | |#当前拥有锁的锁ID +-------------------+-------------+------+-----+---------+-------+ desc information_schema .innodb_trx ; +----------------------------+---------------------+------+-----+---------------------+-------+ | Field | Type | Null | Key | Default | Extra | +----------------------------+---------------------+------+-----+---------------------+-------+ | trx_id | varchar(18) | NO | | | |#事务ID | trx_state | varchar(13) | NO | | | |#事务状态： | trx_started | datetime | NO | | 0000-00-00 00:00:00 | |#事务开始时间； | trx_requested_lock_id | varchar(81) | YES | | NULL | |#innodb_locks.lock_id | trx_wait_started | datetime | YES | | NULL | |#事务开始等待的时间 | trx_weight | bigint(21) unsigned | NO | | 0 | |# | trx_mysql_thread_id | bigint(21) unsigned | NO | | 0 | |#事务线程ID | trx_query | varchar(1024) | YES | | NULL | |#具体SQL语句 | trx_operation_state | varchar(64) | YES | | NULL | |#事务当前操作状态 | trx_tables_in_use | bigint(21) unsigned | NO | | 0 | |#事务中有多少个表被使用 | trx_tables_locked | bigint(21) unsigned | NO | | 0 | |#事务拥有多少个锁 | trx_lock_structs | bigint(21) unsigned | NO | | 0 | |# | trx_lock_memory_bytes | bigint(21) unsigned | NO | | 0 | |#事务锁住的内存大小（B） | trx_rows_locked | bigint(21) unsigned | NO | | 0 | |#事务锁住的行数 | trx_rows_modified | bigint(21) unsigned | NO | | 0 | |#事务更改的行数 | trx_concurrency_tickets | bigint(21) unsigned | NO | | 0 | |#事务并发票数 | trx_isolation_level | varchar(16) | NO | | | |#事务隔离级别 | trx_unique_checks | int(1) | NO | | 0 | |#是否唯一性检查 | trx_foreign_key_checks | int(1) | NO | | 0 | |#是否外键检查 | trx_last_foreign_key_error | varchar(256) | YES | | NULL | |#最后的外键错误 | trx_adaptive_hash_latched | int(1) | NO | | 0 | |# | trx_adaptive_hash_timeout | bigint(21) unsigned | NO | | 0 | |# +----------------------------+---------------------+------+-----+---------------------+------- select * from information_schema.innodb_lock_waits G
