问题
On Mysql (Amazon RDS), when I try to run the following SQL query
UPDATE
table1 INNER JOIN table2 USING (CommonColumn)
SET
table1.col1 = table2.x,
table1.col2 = table2.y
I get this error after around 52 seconds consistently:
Error Code: 1205. Lock wait timeout exceeded; try restarting transaction
How should I resolve this?
table2 has around 17 million records and table2 which is a subset of table1 has 4 million records. Could it be the size of the tables that is the problem or is something wrong with my query?
回答1:
Try increasing the default number of IO threads if you are using InnoDB engine. RDS defaults to a measly 4. You will need to restart the DB instance for the Parameter Group to use the new values as they are not "dynamic" (require a reboot).
show variables like 'innodb_%io_threads';
+-------------------------+-------+
| Variable_name | Value |
+-------------------------+-------+
| innodb_read_io_threads | 4 |
| innodb_write_io_threads | 4 |
+-------------------------+-------+
回答2:
On AWS RDS, I had a DB instance fill up, which caused this error on the client.
回答3:
I restarted the MySQL instance and the same query worked.
来源：https://stackoverflow.com/questions/8060560/mysql-amazon-rds-lock-wait-timeout-exceeded