Is mysql_insert_id Reliable in Concurrent Insertions?

Ensuring the Accuracy of mysql_insert_id in Concurrent Insertions

In PHP, the mysql_insert_id function retrieves the ID of the last inserted row into a MySQL table. However, concerns arise regarding its reliability in situations where multiple rows are inserted rapidly. Specifically, if a website inserts more than two rows per second, can mysql_insert_id still provide the correct ID associated with a particular INSERT query?

Understanding MySQL's ID Management

According to the MySQL manual, the server maintains the generated ID on a per-connection basis. This implies that the value returned by mysql_insert_id to a specific client is the first AUTO_INCREMENT value produced by the most recent statement affecting an AUTO_INCREMENT column executed by that client. Crucially, other clients cannot impact this value, even if they generate their own AUTO_INCREMENT values.

Safety of mysql_insert_id

This behavior ensures that each client can retrieve its own ID without any interference from other clients. This eliminates the need for locks or transactions, simplifying the process.

Conclusion

The MySQL manual explicitly states that using mysql_insert_id in a concurrent insertion scenario does not compromise its accuracy. Each client can confidently rely on the function to provide the ID of the row they inserted, ensuring data integrity and consistency.

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