Why Does My MySQL Application Keep Showing \'Prepared Statement Needs to Be Re-Prepared\'?

MySQL Encountering "Prepared Statement Needs to Be Re-Prepared" Error

Problem:
Upon migrating a PHP-based website with MySQL Stored Procedures to a hosting server, users encounter repeated fatal errors stating "Prepared statement needs to be re-prepared." This issue manifests inconsistently, leading to alternating successful and failed page loads.

Answer:

The underlying cause is a known MySQL bug (#42041) related to the table_definition_cache setting. MySQL recommends increasing the value of this parameter to resolve the issue.

Solution:

1. Adjust the MySQL configuration file (e.g., my.cnf).
2. Locate the parameter table_definition_cache and increase its value.
3. Restart the MySQL service for the changes to take effect.

Understanding Statement Caching:
MySQL utilizes statement caching to enhance performance by storing previously executed statements in memory. When a similar statement is encountered, the cached version is retrieved, reducing the overhead of re-parsing and compiling. By increasing the value of table_definition_cache, MySQL can cache more table definitions, improving the likelihood of reusing cached statements and mitigating the "Prepared statement needs to be re-prepared" error.

Additional Resources:

• [MySQL Documentation on Statement Caching](https://dev.mysql.com/doc/refman/8.0/en/statement-caching.html)
• [MySQL Bug #42041](https://bugs.mysql.com/bug.php?id=42041)

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