To Close or Not to Close: Is Explicitly Closing MySQL Connections in PHP Always Necessary?

The Importance of Closing MySQL Connections

In web applications, the efficiency of database connections is paramount. Whether closing a MySQL connection is crucial or not is a common question that deserves attention.

According to the MySQL documentation, "The link to the server will be closed as soon as the execution of the script ends, unless it's closed earlier by explicitly calling mysql_close()."

Benefits of Closing Connections

If your PHP script involves extensive processing after fetching results and retrieving the full result set, manually closing the connection is highly advisable. Failing to do so may strain the MySQL server's connection limit, especially during high web traffic.

Exceptions to the Rule

However, if your script does not require you to close the connection until near the end, it remains unnecessary to do so explicitly. The connection will automatically close when the script concludes.

FastCGI Considerations

In fastcgi environments, the behavior of PHP connections may differ. Some sources claim that fastcgi builds of PHP establish persistent connections, contradicting the documentation's assertion that connections close when the script ends. For reliability, it's prudent to employ the mysql_close() function explicitly or consider using a more modern PHP database abstraction layer such as PDO.

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