MySQL 5.7 - Row-Level Locking Issues in Concurrent Update Scenarios with InnoDB
I'm attempting to set up I'm having a hard time understanding I'm working with a question with row-level locking while performing concurrent updates on a MySQL 5.7 database using InnoDB... I have two sessions attempting to update the same row in a table, and I'm receiving a deadlock behavior intermittently. Here’s a simplified version of my setup: I have a table named `products` with the following structure: ```sql CREATE TABLE products ( id INT PRIMARY KEY, stock INT NOT NULL ) ENGINE=InnoDB; ``` Session 1 runs: ```sql START TRANSACTION; UPDATE products SET stock = stock - 1 WHERE id = 1; -- Simulate some processing time SELECT SLEEP(5); COMMIT; ``` Session 2 runs: ```sql START TRANSACTION; UPDATE products SET stock = stock + 1 WHERE id = 1; COMMIT; ``` When both sessions are executed at the same time, I occasionally get the following behavior in Session 2: ``` behavior Code: 1213. Deadlock found when trying to get lock; try restarting transaction ``` I understand that InnoDB uses row-level locking and that locks are acquired in a first-come, first-served basis. However, I want to figure out why this deadlock is happening and how to properly handle it. I've tried using `LOCK IN SHARE MODE` in the update statement, but it didn’t resolve the scenario. My goal is to ensure that my updates can be handled smoothly without running into deadlocks. Any suggestions on how to improve this or work around the locking scenario would be greatly appreciated. Additionally, are there any best practices for managing concurrent updates in MySQL that I should be aware of? I recently upgraded to Sql 3.9. This issue appeared after updating to Sql 3.11. Any ideas how to fix this? For context: I'm using Sql on Debian. What's the correct way to implement this?