Solving MySQL Error 1200: Configuring a Server as a Slave for Replication

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MySQL Error 1200 (SQLSTATE HY000) is a common issue faced when setting up or managing replication in MySQL. This error message indicates that the server you are working with has not been correctly configured as a slave. In this post, we’ll explore the steps needed to diagnose and correct this error, ensuring your replication setup functions smoothly.

Diagnosing Error 1200 in MySQL

When you encounter Error 1200, the first step is to check whether the server has been designated as a slave and whether the replication configuration is correct. Here’s how to proceed:

  1. Check the Slave Configuration: Ensure that the server has been correctly configured with the necessary replication parameters using the CHANGE MASTER TO command.
  2. Review MySQL Configuration File: The my.cnf or my.ini file should have the replication-related options set correctly, such as server-id, relay-log, and read-only.
  3. Inspect Replication Status: Use the SHOW SLAVE STATUS\G command to check the current replication status and look for any errors.
  4. Verify Server ID: Each server in a replication setup must have a unique server-id value.

Fixing Error 1200

Based on the diagnostic steps, here are some solutions to fix Error 1200:

Setting the Server as a Slave

If the server hasn’t been set as a slave, use the CHANGE MASTER TO command with the necessary parameters:

CHANGE MASTER TO
  MASTER_HOST='master_host_name',
  MASTER_USER='replication_user',
  MASTER_PASSWORD='replication_password',
  MASTER_LOG_FILE='recorded_log_file_name',
  MASTER_LOG_POS=recorded_log_position;
START SLAVE;

Replace the placeholders with the actual master host details, replication user credentials, and log file position.

Configuring the MySQL Configuration File

Ensure that the my.cnf or my.ini file has the server set up with a unique server ID and other necessary replication settings:

[mysqld]
server-id=2
log_bin=mysql-bin
relay-log=mysql-relay-bin
read-only=1

After making changes, restart the MySQL server.

Checking for Duplicate Server IDs

Make sure that no other server in the replication topology has the same server-id:

SHOW VARIABLES LIKE 'server_id';

If you find a duplicate, change the server-id in the configuration file to a unique value and restart MySQL.

Verifying Replication User and Permissions

The replication user must have the correct permissions on the master:

GRANT REPLICATION SLAVE ON *.* TO 'replication_user'@'slave_host' IDENTIFIED BY 'replication_password';
FLUSH PRIVILEGES;

Also, ensure that you have set the correct replication user credentials in the CHANGE MASTER TO command on the slave.

Conclusion

Error 1200 in MySQL usually points to a misconfiguration in your replication setup. By carefully checking the slave status, server IDs, and configuration files, and ensuring the correct use of the CHANGE MASTER TO command, you can resolve this error and establish a stable replication environment. If after following these steps the problem persists, consult the MySQL documentation or consider reaching out to the MySQL community for further assistance.

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