MySQL · December 20, 2023

How to Fix MySQL Error 1213 - SQLSTATE: 40001 (ER_LOCK_DEADLOCK) Deadlock found when trying to get lock; try restarting transaction

How to Fix MySQL Error 1213 - SQLSTATE: 40001 (ER_LOCK_DEADLOCK) Deadlock found when trying to get lock; try restarting transaction

MySQL is a popular open-source relational database management system used by many websites and applications. However, like any software, it can encounter errors that can disrupt its normal operation. One such error is the MySQL Error 1213, also known as SQLSTATE: 40001 (ER_LOCK_DEADLOCK). This error occurs when there is a deadlock in the database, preventing a transaction from completing successfully. In this article, we will explore the causes of this error and provide solutions to fix it.

Understanding Deadlocks

A deadlock occurs when two or more transactions are waiting for each other to release resources, resulting in a deadlock situation where none of the transactions can proceed. In the case of MySQL, this can happen when multiple transactions are trying to access the same set of resources simultaneously.

When a deadlock is detected, MySQL automatically chooses one of the transactions as the victim and rolls it back to resolve the deadlock. The error message "Deadlock found when trying to get lock; try restarting transaction" indicates that a deadlock has occurred.

Causes of MySQL Error 1213

There are several common causes of MySQL Error 1213:

  • Concurrency Issues: Deadlocks can occur when multiple transactions are trying to access the same set of resources simultaneously. For example, if two transactions are trying to update the same row in a table, a deadlock can occur if they acquire locks on the rows in a different order.
  • Long Transactions: If a transaction holds locks on resources for an extended period, it increases the chances of a deadlock occurring. Long-running transactions should be avoided or optimized to minimize the risk of deadlocks.
  • Inefficient Indexing: Inadequate indexing can lead to table scans and increase the chances of deadlocks. Proper indexing can improve query performance and reduce the likelihood of deadlocks.

Fixing MySQL Error 1213

Here are some solutions to fix MySQL Error 1213:

1. Retry the Transaction

When a deadlock occurs, MySQL automatically rolls back one of the transactions involved in the deadlock. In most cases, retrying the transaction can resolve the deadlock. You can catch the deadlock exception in your application code and retry the transaction after a short delay.

try {
  // Perform the transaction
} catch (DeadlockException $e) {
  // Retry the transaction after a short delay
  sleep(1);
  // Retry the transaction
}

2. Optimize Queries

Review your queries and optimize them to minimize the chances of deadlocks. Ensure that you are using appropriate indexes and avoid long-running transactions. Use the EXPLAIN statement to analyze your queries and identify any potential performance issues.

EXPLAIN SELECT * FROM table_name WHERE column_name = 'value';

3. Use Transactions Wisely

Avoid holding locks for an extended period by keeping your transactions as short as possible. Commit or rollback transactions as soon as they are no longer needed. This reduces the chances of deadlocks and improves concurrency.

START TRANSACTION;
-- Perform your operations
COMMIT;

4. Adjust Isolation Levels

MySQL supports different isolation levels that determine how transactions interact with each other. In some cases, adjusting the isolation level can help avoid deadlocks. However, changing the isolation level can have other implications, so it should be done with caution.

SET TRANSACTION ISOLATION LEVEL READ COMMITTED;

5. Monitor and Analyze Deadlocks

Enable the MySQL error log and monitor it for deadlock-related messages. Analyze the deadlocks to identify patterns and potential causes. This information can help you make informed decisions on how to prevent future deadlocks.

Summary

MySQL Error 1213 (ER_LOCK_DEADLOCK) can occur when there is a deadlock in the database, preventing a transaction from completing successfully. Deadlocks can be caused by concurrency issues, long transactions, and inefficient indexing. To fix this error, you can retry the transaction, optimize queries, use transactions wisely, adjust isolation levels, and monitor and analyze deadlocks. If you encounter MySQL Error 1213, it is important to take appropriate measures to resolve the deadlock and ensure the smooth operation of your MySQL database.

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