MySQL · December 20, 2023

How to Fix MySQL Error - ER_SYNC_MASTER_IGNORED_DDL

How to Fix MySQL Error - ER_SYNC_MASTER_IGNORED_DDL

MySQL is a popular open-source relational database management system used by many websites and applications. However, like any software, it can encounter errors and issues that need to be resolved. One such error is the ER_SYNC_MASTER_IGNORED_DDL error. In this article, we will explore what this error means and how to fix it.

Understanding the ER_SYNC_MASTER_IGNORED_DDL Error

The ER_SYNC_MASTER_IGNORED_DDL error occurs when a MySQL server encounters a data definition language (DDL) statement that it cannot execute due to the server's configuration. DDL statements are used to define or modify the structure of database objects such as tables, indexes, or views.

When this error occurs, the MySQL server ignores the DDL statement and continues processing other statements. This behavior is controlled by the sync_master_info system variable, which determines whether the server should stop replication when encountering such statements.

Causes of the ER_SYNC_MASTER_IGNORED_DDL Error

There are several reasons why you might encounter the ER_SYNC_MASTER_IGNORED_DDL error:

  • Replication Configuration: If the sync_master_info system variable is set to a value other than 1, the server will ignore DDL statements and generate this error.
  • Unsupported DDL Statements: Some DDL statements are not supported in MySQL replication, such as those that modify the table structure in a way that cannot be replicated to the slave.
  • Version Incompatibility: The ER_SYNC_MASTER_IGNORED_DDL error can also occur if the master and slave servers are running different versions of MySQL, and the DDL statement is not compatible with the slave's version.

Fixing the ER_SYNC_MASTER_IGNORED_DDL Error

To fix the ER_SYNC_MASTER_IGNORED_DDL error, you can take the following steps:

1. Check Replication Configuration

First, verify that the sync_master_info system variable is set to 1 on both the master and slave servers. You can do this by running the following SQL command:

SHOW VARIABLES LIKE 'sync_master_info';

If the value is not 1, you can change it by modifying the MySQL configuration file (my.cnf or my.ini) and adding the following line under the [mysqld] section:

sync_master_info = 1

After making the change, restart the MySQL server for the new configuration to take effect.

2. Modify DDL Statements

If the error persists, review the DDL statements that are causing the error. Consider whether these statements are necessary for replication or if they can be modified to be compatible with the slave server.

For example, if you are using ALTER TABLE statements to modify the table structure, ensure that the changes can be replicated to the slave without causing conflicts. You may need to use alternative methods or break down the DDL statements into smaller steps.

3. Upgrade MySQL Versions

If the master and slave servers are running different versions of MySQL, consider upgrading the slave server to match the master's version. This ensures compatibility and reduces the likelihood of encountering replication errors.

Before upgrading, make sure to backup your databases and test the upgrade process in a non-production environment.

Summary

In conclusion, the ER_SYNC_MASTER_IGNORED_DDL error in MySQL occurs when the server encounters a DDL statement that it cannot execute due to its configuration. To fix this error, you should check the replication configuration, modify unsupported DDL statements, and consider upgrading MySQL versions if necessary.

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