This guide helps resolve an error of type "Invalid query: MySQL server has gone away".

Preamble

• This type of error often originates from keeping a MySQL connection open without submitting requests for a period of time beyond which the connection is closed: http://dev.mysql.com/doc/refman/5.7/en/gone-away.html
• The variables wait_timeout and interactive_timeout that control this disconnection are set to 30 seconds: http://dev.mysql.com/doc/refman/5.0/en/communication-errors.html

Solutions

To avoid the "MySQL server has gone away" error, here are several possible approaches:

Verification and automatic reconnection

Before executing a query, it is recommended to test if the MySQL connection is still active. If the connection has been closed, you can automatically re-establish it before proceeding with your query. Here is an example in PHP:

if (!mysqli_ping($connexion)) {
mysqli_close($connexion);
$connexion = mysqli_connect($host, $user, $password, $database);
}

The function mysqli_ping() checks if the connection is still valid. If it is not, the script closes the connection and opens a new one.

Regular "Ping" sending

Another method is to run a script that regularly sends a "ping" to the database to keep the connection active. For example, you could create a scheduled task (cron job) that sends a light query, such as SELECT 1; at regular intervals.

Adjusting MySQL parameters (Cloud Server)

With a Cloud Server, you can increase the values of the variables wait_timeout and interactive_timeout from the MySQL menu of your server to extend the duration of the connection before it is closed.