native histograms: only reduce resolution for exponential histograms

Currently we can only reduce the resolution of exponential native
histograms, so checking the schema for that is slightly more precise
than checking against max schema.

Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>

scrape/target.go

@@ -365,7 +365,7 @@ type bucketLimitAppender struct {
 
 func (app *bucketLimitAppender) AppendHistogram(ref storage.SeriesRef, lset labels.Labels, t int64, h *histogram.Histogram, fh *histogram.FloatHistogram) (storage.SeriesRef, error) {
 	if h != nil {
-		if len(h.PositiveBuckets)+len(h.NegativeBuckets) > app.limit && h.Schema > histogram.ExponentialSchemaMax {
+		if len(h.PositiveBuckets)+len(h.NegativeBuckets) > app.limit && !histogram.IsExponentialSchema(h.Schema) {
 			return 0, errBucketLimit
 		}
 		for len(h.PositiveBuckets)+len(h.NegativeBuckets) > app.limit {
@@ -376,7 +376,7 @@ func (app *bucketLimitAppender) AppendHistogram(ref storage.SeriesRef, lset labe
 		}
 	}
 	if fh != nil {
-		if len(fh.PositiveBuckets)+len(fh.NegativeBuckets) > app.limit && fh.Schema > histogram.ExponentialSchemaMax {
+		if len(fh.PositiveBuckets)+len(fh.NegativeBuckets) > app.limit && !histogram.IsExponentialSchema(fh.Schema) {
 			return 0, errBucketLimit
 		}
 		for len(fh.PositiveBuckets)+len(fh.NegativeBuckets) > app.limit {