From a76fe9dea26871e8a6c494024bc9927fe73b8142 Mon Sep 17 00:00:00 2001
From: Alan West <3676547+alanwest@users.noreply.github.com>
Date: Mon, 30 Sep 2024 20:43:59 -0700
Subject: [PATCH] Clarify aggregation temporality for Summary metric type
 (#591)

---
 opentelemetry/proto/metrics/v1/metrics.proto | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/opentelemetry/proto/metrics/v1/metrics.proto b/opentelemetry/proto/metrics/v1/metrics.proto
index 1a9e0b77c..45e656735 100644
--- a/opentelemetry/proto/metrics/v1/metrics.proto
+++ b/opentelemetry/proto/metrics/v1/metrics.proto
@@ -268,6 +268,9 @@ message ExponentialHistogram {
 // data type. These data points cannot always be merged in a meaningful way.
 // While they can be useful in some applications, histogram data points are
 // recommended for new applications.
+// Summary metrics do not have an aggregation temporality field. This is
+// because the count and sum fields of a SummaryDataPoint are assumed to be
+// cumulative values.
 message Summary {
   repeated SummaryDataPoint data_points = 1;
 }
@@ -606,7 +609,8 @@ message ExponentialHistogramDataPoint {
 }
 
 // SummaryDataPoint is a single data point in a timeseries that describes the
-// time-varying values of a Summary metric.
+// time-varying values of a Summary metric. The count and sum fields represent
+// cumulative values.
 message SummaryDataPoint {
   reserved 1;