Why Does My MySQL Prepared Statement Need Re-preparation?

MySQL Prepared Statement Requires Re-Preparation: Troubleshooting "Prepared statement needs to be re-prepared" Error

When encountering the "Prepared statement needs to be re-prepared" error in MySQL, it indicates an inconsistency between the server and client versions of a table definition. Typically, this issue arises after migrating code involving MySQL Stored Procedures to a hosting server.

Cause of the Error:

The error occurs because MySQL maintains a cache of table metadata, which is used to optimize performance by reducing the need to retrieve column information for every query. However, if the table structure changes between the versions on the local machine and the hosting server, the cached metadata becomes outdated and the statement can no longer be executed successfully.

Potential Solution:

As suggested by MySQL bug #42041, increasing the value of the "table_definition_cache" variable can resolve the issue. This variable specifies the number of tables that MySQL will cache. By increasing the cache size, you can reduce the likelihood of discrepancies between the cached and actual table definitions.

Instructions:

1. Log in to the MySQL server using a tool such as phpMyAdmin or the MySQL command line.
2. Run the following command to increase the "table_definition_cache" value:

SET GLOBAL table_definition_cache = <new_value>;

3. Replace with a larger value, such as 1024 or 2048.
4. Restart the MySQL server to apply the changes.

Reference:

For more information on statement caching in MySQL, refer to the official MySQL documentation: https://dev.mysql.com/doc/refman/8.0/en/statement-cache.html

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