MongoDB\Driver\Monitoring\CommandStartedEvent::getOperationId — Returns the command's operation ID
The operation ID is generated by the driver and may be used to link events together such as bulk write operations, which may have been split across several commands at the protocol level.
Note: Since multiple commands may share the same operation ID, it is not reliable to use this value to associate event objects with each other. The request ID returned by MongoDB\Driver\Monitoring\CommandStartedEvent::getRequestId() should be used instead.
This function has no parameters.
Returns the command's operation ID.