InnoDB 支持两种意向锁

意向共享锁LOCK IN SHARE MODE

SELECT * FROM Country WHERE Code='AUS'LOCK IN SHARE MODE\G

意向互斥锁FOR UPDATE

SELECT counter_field INTO @@counter_field FROM child_codes FOR UPDATE;

UPDATE child_codes SET counter_field = @@counter_field + 1;

InnoDB的行级锁

Record lock

Gap lock

Next-key lock

--查看锁等待事务

select * from innodb_lock_waits;

select * from innodb_locks;

select trx_id,trx_mysql_thread_id,trx_query,trx_rows_locked from innodb_trx;

 -- innodb_locks ## 当前出现的锁

mysql > desc 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
+-------------+---------------------+------+-----+---------+-------+

-- innodb_lock_waits ## 锁等待的对应关系

mysql > desc 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
+-------------------+-------------+------+-----+---------+-------+

-- innodb_trx ## 当前运行的所有事务 

> desc 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 | |#innodINNODB_TRXb_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 | |#
+----------------------------+---------------------+------+-----+---------------------+-------+