comments

src/OpenTelemetry/Metrics/MetricStreamConfiguration.cs

@@ -1,6 +1,9 @@
 // Copyright The OpenTelemetry Authors
 // SPDX-License-Identifier: Apache-2.0
 
+#if EXPOSE_EXPERIMENTAL_FEATURES && NET8_0_OR_GREATER
+using System.Diagnostics.CodeAnalysis;
+#endif
 using OpenTelemetry.Internal;
 
 namespace OpenTelemetry.Metrics;
@@ -106,6 +109,9 @@ public string[]? TagKeys
     /// SetMaxMetricPointsPerMetricStream"/> to confiture the SDK defaults.
     /// </remarks>
 #if EXPOSE_EXPERIMENTAL_FEATURES
+#if NET8_0_OR_GREATER
+[Experimental(DiagnosticDefinitions.CardinalityLimitExperimentalApi, UrlFormat = DiagnosticDefinitions.ExperimentalApiUrlFormat)]
+#endif
     public
 #else
     internal
@@ -117,7 +123,7 @@ public string[]? TagKeys
         {
             if (value != null)
             {
-                Guard.ThrowIfOutOfRange(value.Value, min: 3, max: int.MaxValue);
+                Guard.ThrowIfOutOfRange(value.Value, min: 1, max: int.MaxValue);
             }
 
             this.cardinalityLimit = value;

src/Shared/DiagnosticDefinitions.cs

@@ -12,4 +12,5 @@ internal static class DiagnosticDefinitions
     public const string LoggerProviderExperimentalApi = "OTEL1000";
     public const string LogsBridgeExperimentalApi = "OTEL1001";
     public const string ExemplarExperimentalApi = "OTEL1002";
+    public const string CardinalityLimitExperimentalApi = "OTEL1003";
 }

test/OpenTelemetry.Tests/Metrics/MetricViewTests.cs

@@ -921,7 +921,7 @@ public void ViewConflict_OneInstrument_DifferentDescription()
     }
 
     [Fact]
-    public void MaxMetricPointsPerMetricStreamofMatchingViewTakesPrecedenceOverTheMetricReaderWhenBothWereSet()
+    public void CardinalityLimitofMatchingViewTakesPrecedenceOverMetricProviderWhenBothWereSet()
     {
         using var meter = new Meter(Utils.GetCurrentMethodName());
         var exportedItems = new List<Metric>();
@@ -969,7 +969,7 @@ public void ViewConflict_TwoDistinctInstruments_ThreeStreams()
             })
             .AddView((instrument) =>
             {
-                // This view is ignored as the passed in MaxMetricPointsPerMetricStream is out of range.
+                // This view is ignored as the passed in CardinalityLimit is out of range.
                 return new MetricStreamConfiguration() { Name = "MetricStreamD", CardinalityLimit = -1 };
             })
             .AddInMemoryExporter(exportedItems));