Interpreting Stackdriver Metrics meaning "Sampled every 60 seconds. After sampling, data is not visible for up to 240 seconds"

Question

We are in process of identifying Stackdriver metrics

I am specifically looking at GCP predefined metric subscription/ack_message_count with description Cumulative count of messages acknowledged by Acknowledge requests, grouped by delivery type. Sampled every 60 seconds. After sampling, data is not visible for up to 240 seconds.

Can any one help me understand highlighted part, what does Sampled every 60 seconds. After sampling, data is not visible for up to 240 seconds. mean

once i check this metric will it not able available for next 240 seconds.

Thanks

Answer 1

From my understanding, the data is polled every 60 seconds but at the metrics creation the time until the data is polled would take up to 240 seconds. The BigQuery section makes this a bit clearer. Because the numbers are as such that it would not be feasible in an other context

Example: Scanned bytes. Sampled every 60 seconds. After sampling, data is not visible for up to 21720 seconds.