How Can I Limit Query Execution Time in MySQL?

Enforcing Query Execution Time Limits in MySQL

Question: Can I configure MySQL to restrict the execution time of queries?

Answer: Historically, MySQL lacked a built-in mechanism for limiting query execution time. However, recent updates to MySQL 5.7 introduce the MAX_EXECUTION_TIME optimizer hint.

MAX_EXECUTION_TIME Optimizer Hint:

As of MySQL 5.7, you can include the MAX_EXECUTION_TIME optimizer hint in SELECT queries. This hint instructs the server to terminate the query if it exceeds the specified time limit.

SELECT * FROM table_name WHERE condition LIMIT 1 MAX_EXECUTION_TIME=10;

Server-Wide Timeouts:

If you require a server-wide timeout or need to limit queries other than SELECTs, the original answer provided remains your best option.

Cron Job Approach:

The original answer suggests setting up a cron job that periodically checks for and terminates any queries exceeding a predefined time limit. This approach involves running the following steps:

1. Execute SHOW PROCESSLIST to retrieve a list of running processes.
2. Identify processes with query times exceeding the desired limit.
3. Use KILL [process id] to terminate the offending processes.

Additional Considerations:

While the MAX_EXECUTION_TIME hint is convenient, it only applies to SELECT queries and cannot be enforced at the server level. The cron job approach provides a more robust solution for enforcing time limits across all query types.

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