PromQL: improve warning for mixed values in aggregations

Aggregations discard the metric name, so don't try to
include it in the error message.

Add a test that generates this warning.

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>

promql/engine.go

@@ -2869,8 +2869,7 @@ func (ev *evaluator) aggregation(e *parser.AggregateExpr, grouping []string, par
 		case parser.AVG:
 			if aggr.hasFloat && aggr.hasHistogram {
 				// We cannot aggregate histogram sample with a float64 sample.
-				metricName := aggr.labels.Get(labels.MetricName)
+				annos.Add(annotations.NewMixedFloatsHistogramsAggWarning(e.Expr.PositionRange()))
-				annos.Add(annotations.NewMixedFloatsHistogramsWarning(metricName, e.Expr.PositionRange()))
 				continue
 			}
 			if aggr.hasHistogram {
@@ -2923,8 +2922,7 @@ func (ev *evaluator) aggregation(e *parser.AggregateExpr, grouping []string, par
 		case parser.SUM:
 			if aggr.hasFloat && aggr.hasHistogram {
 				// We cannot aggregate histogram sample with a float64 sample.
-				metricName := aggr.labels.Get(labels.MetricName)
+				annos.Add(annotations.NewMixedFloatsHistogramsAggWarning(e.Expr.PositionRange()))
-				annos.Add(annotations.NewMixedFloatsHistogramsWarning(metricName, e.Expr.PositionRange()))
 				continue
 			}
 			if aggr.hasHistogram {

promql/engine_test.go

@@ -4315,6 +4315,8 @@ func TestNativeHistogram_Sum_Count_Add_AvgOperator(t *testing.T) {
 
 				ts := idx0 * int64(10*time.Minute/time.Millisecond)
 				app := storage.Appender(context.Background())
+				_, err := app.Append(0, labels.FromStrings("__name__", "float_series", "idx", "0"), ts, 42)
+				require.NoError(t, err)
 				for idx1, h := range c.histograms {
 					lbls := labels.FromStrings("__name__", seriesName, "idx", fmt.Sprintf("%d", idx1))
 					// Since we mutate h later, we need to create a copy here.
@@ -4344,17 +4346,31 @@ func TestNativeHistogram_Sum_Count_Add_AvgOperator(t *testing.T) {
 
 					res := qry.Exec(context.Background())
 					require.NoError(t, res.Err)
+					require.Empty(t, res.Warnings)
 
 					vector, err := res.Vector()
 					require.NoError(t, err)
 
 					testutil.RequireEqual(t, exp, vector)
 				}
+				queryAndCheckAnnotations := func(queryString string, ts int64, expWarnings annotations.Annotations) {
+					qry, err := engine.NewInstantQuery(context.Background(), storage, nil, queryString, timestamp.Time(ts))
+					require.NoError(t, err)
+
+					res := qry.Exec(context.Background())
+					require.NoError(t, res.Err)
+					require.Equal(t, expWarnings, res.Warnings)
+				}
 
 				// sum().
 				queryString := fmt.Sprintf("sum(%s)", seriesName)
 				queryAndCheck(queryString, ts, []Sample{{T: ts, H: &c.expected, Metric: labels.EmptyLabels()}})
 
+				queryString = `sum({idx="0"})`
+				var annos annotations.Annotations
+				annos.Add(annotations.NewMixedFloatsHistogramsAggWarning(posrange.PositionRange{Start: 4, End: 13}))
+				queryAndCheckAnnotations(queryString, ts, annos)
+
 				// + operator.
 				queryString = fmt.Sprintf(`%s{idx="0"}`, seriesName)
 				for idx := 1; idx < len(c.histograms); idx++ {

util/annotations/annotations.go

@@ -105,7 +105,7 @@ var (
 
 	InvalidQuantileWarning              = fmt.Errorf("%w: quantile value should be between 0 and 1", PromQLWarning)
 	BadBucketLabelWarning               = fmt.Errorf("%w: bucket label %q is missing or has a malformed value", PromQLWarning, model.BucketLabel)
-	MixedFloatsHistogramsWarning        = fmt.Errorf("%w: encountered a mix of histograms and floats for metric name", PromQLWarning)
+	MixedFloatsHistogramsWarning        = fmt.Errorf("%w: encountered a mix of histograms and floats for ", PromQLWarning)
 	MixedClassicNativeHistogramsWarning = fmt.Errorf("%w: vector contains a mix of classic and native histograms for metric name", PromQLWarning)
 	NativeHistogramNotCounterWarning    = fmt.Errorf("%w: this native histogram metric is not a counter:", PromQLWarning)
 	NativeHistogramNotGaugeWarning      = fmt.Errorf("%w: this native histogram metric is not a gauge:", PromQLWarning)
@@ -155,7 +155,16 @@ func NewBadBucketLabelWarning(metricName, label string, pos posrange.PositionRan
 func NewMixedFloatsHistogramsWarning(metricName string, pos posrange.PositionRange) error {
 	return annoErr{
 		PositionRange: pos,
-		Err:           fmt.Errorf("%w %q", MixedFloatsHistogramsWarning, metricName),
+		Err:           fmt.Errorf("%w metric name %q", MixedFloatsHistogramsWarning, metricName),
+	}
+}
+
+// NewMixedFloatsHistogramsAggWarning is used when the queried series includes both
+// float samples and histogram samples in an aggregation.
+func NewMixedFloatsHistogramsAggWarning(pos posrange.PositionRange) error {
+	return annoErr{
+		PositionRange: pos,
+		Err:           fmt.Errorf("%w aggregation", MixedFloatsHistogramsWarning),
 	}
 }