How can I stop a MySQL query if it takes too long?

Question

Is it possible to timeout a query in MySQL?

That is, if any query exceeds the time I specify, it will be killed by MySQL and it will return an error instead of waiti

Answer 1

I think this old question needs an updated answer.

You can set a GLOBAL timeout for all your read-only SELECT queries like this:

SET GLOBAL MAX_EXECUTION_TIME=1000;

The time specified is in milliseconds.

If you want the timeout only for a specific query, you can set it inline like this:

SELECT /*+ MAX_EXECUTION_TIME(1000) */ my_column FROM my_table WHERE ...

MySQL returns an error instead of waiting for eternity.

Note that this method only works for read-only SELECTs. If a SELECT statement is determined not to be read-only, then any timer set for it is cancelled and the following NOTE message is reported to the user:

Note 1908 Select is not a read only statement, disabling timer

For statements with subqueries, it limits the top SELECT only. It does not apply to SELECT statements within stored programs. Using the MAX_EXECUTION_TIME hint in SELECT statements within a stored program will be ignored.

Answer 2

Here is my script :

mysql -e 'show processlist\G' |\
egrep -b5 'Time: [6-9]{3,10}' |\
grep 'Id:' |\
cut -d':' -f2 |\
grep -v '155' |\ ## Binary Log PID
sed 's/^ //' |\
while read id
do
    mysql -e "kill $id;"
done

Answer 3

Starting with MySQL 5.1 you can create a stored procedure to query the information_schmea.PROCESSLIST table for all queries that match your criteria for "long running" then iterate over a cursor to kill them. Then setup that procedure to execute on a recurring basis in the event scheduler.

See: http://forge.mysql.com/tools/tool.php?id=106