How Can I Set a Maximum Execution Time for MySQL Queries?

Setting Maximum Execution Time for MySQL Queries

In PHP, the set_time_limit() function allows developers to limit the maximum execution time of scripts. However, there is no direct equivalent for setting such limits for MySQL queries.

Historically, MySQL didn't provide a way to enforce execution time limits. However, this changed with the introduction of MySQL 5.7.4.

Introducing max_execution_time

In MySQL 5.7.4, the max_execution_time variable was introduced. This variable allows you to specify the maximum execution time in milliseconds for top-level read-only SELECT statements.

To use this feature, you can add the following syntax to your SELECT statement:

SELECT 
/*+ MAX_EXECUTION_TIME(1000) */ --in milliseconds
* 
FROM table;

This will set the maximum execution time for the query to 1000 milliseconds (1 second).

Note: This feature only applies to read-only SELECT statements.

Renaming to max_execution_time

In MySQL 5.7.8, the max_execution_time variable was renamed to max_execution_time for consistency.

Additional Information

• The max_execution_time variable can be set globally or per session.
• The default value for max_execution_time is 0, which means no time limit.
• If the execution time of a query exceeds the specified limit, MySQL will terminate the query and return an error.

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