mysqldump: Error 2013: Lost connection to MySQL server during query when dump

Introduction

When using the mysqldump command to create a backup of your MySQL database, you may encounter an error message like mysqldump: Error 2013: Lost connection to MySQL server during query when dump. This error occurs when the connection to the MySQL server is lost while executing a query during the backup process. In this article, we will discuss the possible causes of this error and provide some solutions to resolve it.

Possible Causes

  1. Timeout settings: By default, MySQL has a query execution timeout of 8 hours (28800 seconds). If a query takes longer than this timeout value, the connection will be closed, resulting in the error. This could happen if you have a large database or complex queries that take a long time to execute.

  2. Insufficient resources: If your server does not have enough resources like memory or CPU power to handle the backup process, it may result in a lost connection error. This can occur if you are running other resource-intensive processes simultaneously.

  3. Network issues: A weak or unstable network connection between your MySQL server and the client running the mysqldump command can cause the connection to be lost during the backup process.

Solutions

1. Increase the Timeout Value

One solution is to increase the timeout value for the MySQL server. You can do this by modifying the wait_timeout and interactive_timeout variables in the MySQL configuration file (my.cnf or my.ini). Here is an example of how to set the timeout to 24 hours (86400 seconds):

[mysqld]
wait_timeout = 86400
interactive_timeout = 86400

After making the changes, restart the MySQL server to apply the new timeout values.

2. Split the Backup into Smaller Parts

If you have a large database or complex queries, it may be helpful to split the backup process into smaller parts. Instead of creating a single backup file, you can create multiple dump files for different tables or sections of your database. This reduces the overall execution time of each query and decreases the chances of encountering a lost connection error.

Here is an example of how to backup specific tables using the --tables option:

mysqldump -u username -p --tables database_name table1 table2 > backup.sql

3. Optimize Database and Queries

Optimizing your database and queries can help reduce their execution time and decrease the chances of encountering a lost connection error. You can use tools like the MySQL EXPLAIN statement or query profiling to analyze and optimize your queries. Additionally, you can optimize your database by creating indexes, removing unnecessary data, or partitioning large tables.

4. Check and Improve Server Resources

Ensure that your server has sufficient resources to handle the backup process. Monitor the server's memory, CPU, and disk usage during the backup process to identify any bottlenecks. If necessary, allocate more resources to your server or consider upgrading to a more powerful server.

5. Check Network Connection

If you suspect network issues, check the connectivity between your MySQL server and the client running the mysqldump command. Ensure that the network connection is stable and there are no network interruptions. You can also try running the backup process on the same server as MySQL to eliminate any network-related problems.

Conclusion

The mysqldump: Error 2013: Lost connection to MySQL server during query when dump error can be frustrating when creating backups of your MySQL database. In this article, we discussed the possible causes of this error and provided several solutions to resolve it. By increasing the timeout value, splitting the backup, optimizing database and queries, checking server resources, and verifying network connection, you can minimize the chances of encountering this error and successfully create backups of your MySQL database.