Support quantiles with Summary Metric for Amazon CloudWatch interoperability

[alolita]

What are you trying to achieve?

We have a use case for reporting min, max and arbitrary quantile values (e.g. p99) recorded over an interval in the OTLP metrics.proto. Our use case was fully supported earlier by the Summary datatype which was removed in open-telemetry/opentelemetry-proto#199.

Currently there is no clean way of even reporting the min and max values, however that may become possible with issue 982. We additionally require support for reporting arbitrary quantiles.

What did you expect to see?

We would like a form of the Summary data type to be reintroduced into OTLP capable of supporting the reporting of arbitrary quantiles. When Summary was removed the change was described as temporary. What is the current timeline for its reintroduction?

Additional context.

As mentioned above we believe that a viable alternative for min/max may be to have them transported in the Histogram datatypes as one of the options in issue 982.

The other way we have considered it to encode them as exemplars in the histogram format. While possible for min and max

{
 0, // this is either the min or max ( min in this case)
 timestamp
},
{
 100, // this is either the min or max ( max in this case)
 timestamp
}

it seems less reasonable for arbitrary quantiles as we have no easy way of encoding which percentile the value corresponds to.

cc: @bogdandrutu @jmacd @tigrannajaryan @amanbrar1999 @JasonXZLiu

[gcacace]

Proposal in open-telemetry/opentelemetry-proto#227

[weyert]

Can't this ticket be closed as open-telemetry/opentelemetry-proto#227 got merged?