MySQL 5.7: Deadlock issues when using InnoDB with multiple concurrent INSERTs and SELECTs
I've been struggling with this for a few days now and could really use some help. I just started working with I'm stuck on something that should probably be simple. I'm working with deadlock issues in my MySQL 5.7 database when multiple processes are trying to perform concurrent `INSERT` and `SELECT` operations on the same table. The table has a unique constraint on a column that is being inserted into, and I often get a `Deadlock found when trying to get lock; try restarting transaction` behavior. Here’s a simplified version of what my code looks like: ```php try { $pdo->beginTransaction(); $stmt = $pdo->prepare("INSERT INTO my_table (unique_column, other_column) VALUES (?, ?)"); $stmt->execute([$uniqueValue, $otherValue]); // Simulating a SELECT query that could potentially cause a deadlock $selectStmt = $pdo->prepare("SELECT * FROM my_table WHERE unique_column = ?"); $selectStmt->execute([$uniqueValue]); $pdo->commit(); } catch (Exception $e) { $pdo->rollBack(); echo "Transaction failed: " . $e->getMessage(); } ``` I have tried adding `SELECT ... FOR UPDATE` in my `SELECT` queries, but it doesn't seem to resolve the scenario. Additionally, I've inspected the execution plan and it seems like the deadlocks are happening due to a mix of read and write locks. Could it be a question with transaction isolation levels? I've set it to `REPEATABLE READ`, but I'm considering changing it to `READ COMMITTED`. Would this help alleviate the deadlocks? Any suggestions on best practices or configurations to avoid these deadlocks would be appreciated. I'm developing on Ubuntu 22.04 with Php. Has anyone else encountered this? I'm working with Php in a Docker container on CentOS. Any ideas what could be causing this?