When using PHP with connection pooling enabled, the the change user command is used to ping a connection within a pool to ensure that the connection is open and active before using it. The Tungsten Connector uses JDBC to connector to MySQL, which does not support the change user protocol option.
To provide an alternative to this for PHP applications communication
through the connector, the connector can be configured to respond to the
COM_CHANGE_USER command from a
client application. Rather than performing the change user operation,
instead the connector will respond to the client with an
acknowledgement, emulating the ping operation.
This operation is disabled by default, and must be explicitly enabled.
This can be achieved by setting the correct property value,
true during configuration with
tpm configure alpha --property=treat.com.change.user.as.ping=true