MySQL · December 20, 2023

How to Fix MySQL Error 1089 - SQLSTATE: HY000 (ER_WRONG_SUB_KEY) Incorrect sub part key; the used key part isn't a string, the used length is longer than the key part, or the storage engine doesn't support unique sub keys

How to Fix MySQL Error 1089 - SQLSTATE: HY000 (ER_WRONG_SUB_KEY)

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 MySQL Error 1089 - SQLSTATE: HY000 (ER_WRONG_SUB_KEY). This error occurs when there is an issue with the sub part key used in a query. In this article, we will explore the causes of this error and provide solutions to fix it.

Causes of MySQL Error 1089

There are several possible causes for MySQL Error 1089:

  • Incorrect sub part key: This error can occur if the sub part key used in the query is incorrect. It means that the key part being used is not a string or is longer than the specified key part.
  • Storage engine limitations: Some storage engines in MySQL do not support unique sub keys. If you are using such an engine and try to create a unique sub key, you may encounter this error.

Fixing MySQL Error 1089

Here are some solutions to fix MySQL Error 1089:

1. Check the sub part key

If you are getting the error message "Incorrect sub part key," review the query and ensure that the sub part key being used is correct. Make sure it is a string and not longer than the specified key part. If necessary, modify the query to use the correct sub part key.

2. Use a different storage engine

If the storage engine you are using does not support unique sub keys, consider switching to a different engine that does. InnoDB, for example, supports unique sub keys. You can modify the table's storage engine using the ALTER TABLE statement.

ALTER TABLE table_name ENGINE = InnoDB;

3. Remove the unique sub key constraint

If you do not require a unique sub key, you can remove the unique constraint from the table. This can be done using the ALTER TABLE statement.

ALTER TABLE table_name DROP INDEX index_name;

Replace table_name with the name of your table and index_name with the name of the index that contains the unique sub key constraint.

4. Update MySQL version

If you are using an older version of MySQL, consider updating to the latest version. Newer versions often include bug fixes and improvements that can resolve issues like MySQL Error 1089.

Summary

MySQL Error 1089 - SQLSTATE: HY000 (ER_WRONG_SUB_KEY) can occur due to an incorrect sub part key or limitations of the storage engine being used. To fix this error, review the sub part key used in the query, consider using a different storage engine, remove the unique sub key constraint if not needed, or update MySQL to the latest version. If you are looking for reliable VPS hosting solutions, consider Server.HK. Our high-performance VPS hosting plans are designed to meet the needs of businesses of all sizes.

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