SSE: Reduce to add warning notice to only the first result (#74940)

pkg/expr/commands.go

@@ -166,7 +166,7 @@ func (gr *ReduceCommand) Execute(ctx context.Context, _ time.Time, vars mathexp.
 	span.SetAttributes("reducer", gr.Reducer, attribute.Key("reducer").String(gr.Reducer))
 
 	newRes := mathexp.Results{}
-	for _, val := range vars[gr.VarToReduce].Values {
+	for i, val := range vars[gr.VarToReduce].Values {
 		switch v := val.(type) {
 		case mathexp.Series:
 			num, err := v.Reduce(gr.refID, gr.Reducer, gr.seriesMapper)
@@ -184,7 +184,7 @@ func (gr *ReduceCommand) Execute(ctx context.Context, _ time.Time, vars mathexp.
 			}
 			copyV := mathexp.NewNumber(gr.refID, v.GetLabels())
 			copyV.SetValue(value)
-			if gr.seriesMapper == nil {
+			if gr.seriesMapper == nil && i == 0 { // Add notice to only the first result to not multiple them in presentation
 				copyV.AddNotice(data.Notice{
 					Severity: data.NoticeSeverityWarning,
 					Text:     fmt.Sprintf("Reduce operation is not needed. Input query or expression %s is already reduced data.", gr.VarToReduce),

pkg/expr/commands_test.go

@@ -133,12 +133,12 @@ func TestReduceExecute(t *testing.T) {
 				require.Equal(t, expectedValue, actualValue)
 			}
 
-			t.Run("should add warn notices to every frame", func(t *testing.T) {
+			t.Run("should add warn notices to the first frame", func(t *testing.T) {
 				frames := execute.Values.AsDataFrames("test")
-				for _, frame := range frames {
-					require.Len(t, frame.Meta.Notices, 1)
-					notice := frame.Meta.Notices[0]
-					require.Equal(t, data.NoticeSeverityWarning, notice.Severity)
+				notice := frames[0].Meta.Notices[0]
+				require.Equal(t, data.NoticeSeverityWarning, notice.Severity)
+				for _, frame := range frames[1:] {
+					require.Empty(t, frame.Meta.Notices)
 				}
 			})
 		})