### Diagnostic Dump
The notification daemon can also dump its metrics to stderr whether or not the exporter
is configured. This is particularly useful for cases where metrics data is needed but the
exporter was not enabled.
To trigger this diagnostic dump, send a Postgres notification with the
`hydra_notify_dump_metrics` channel and no payload. See
[Re-sending a notification](../notifications.md#re-sending-a-notification).

$listener->subscribe("hydra_notify_dump_metrics");

        if ($channelName eq "hydra_notify_dump_metrics") {
            print STDERR "Dumping prometheus metrics:\n${\$prom->format}\n";
            next;
        }