diff --git a/flusher.go b/flusher.go
index ea8631ae2..33c6f730f 100644
--- a/flusher.go
+++ b/flusher.go
@@ -44,6 +44,20 @@ func (s *Server) Flush(ctx context.Context) {
 
 	if s.CountUniqueTimeseries {
 		s.Statsd.Count("flush.unique_timeseries_total", s.tallyTimeseries(), []string{fmt.Sprintf("global_veneur:%t", !s.IsLocal())}, 1.0)
+		s.Statsd.Count("flush.unique_timeseries_daily_cumulative", int64(s.cumulativeTimeseries.Estimate()), []string{"veneurglobalonly:true"}, 1.0)
+
+		t := time.Now()
+
+		// Ensure that the cumulative daily count is reset around midnight.
+		// It will reset at most 6 times between 00:00:00 and 00:01:00, which is
+		// an acceptable level of precision for this estimate.
+		// (Skipping at most five flush cycles' worth of data in the cumulative count
+		// will be unnoticable)
+		// The alternative would require using synchronization such as a time.Ticker
+		// and a lock around the HLL, which is overkill and fiddly.
+		if t.Minute() == 0 && t.Hour() == 0 {
+			s.cumulativeTimeseries = hyperloglog.New()
+		}
 	}
 
 	samples := s.EventWorker.Flush()
@@ -140,6 +154,7 @@ func (s *Server) tallyTimeseries() int64 {
 		w.uniqueMTS = hyperloglog.New()
 		w.uniqueMTSMtx.Unlock()
 	}
+	s.cumulativeTimeseries.Merge(allTimeseries)
 	return int64(allTimeseries.Estimate())
 }
 
diff --git a/server.go b/server.go
index 0cbc69bbd..0651e5c94 100644
--- a/server.go
+++ b/server.go
@@ -58,6 +58,8 @@ import (
 	"github.com/stripe/veneur/v14/ssf"
 	"github.com/stripe/veneur/v14/trace"
 	"github.com/stripe/veneur/v14/trace/metrics"
+
+	"github.com/axiomhq/hyperloglog"
 )
 
 // VERSION stores the current veneur version.
@@ -148,6 +150,8 @@ type Server struct {
 
 	stuckIntervals int
 	lastFlushUnix  int64
+
+	cumulativeTimeseries *hyperloglog.Sketch
 }
 
 type GlobalListeningPerProtocolMetrics struct {
@@ -314,6 +318,8 @@ func NewFromConfig(logger *logrus.Logger, conf Config) (*Server, error) {
 	}
 	ret.HistogramAggregates.Count = len(conf.Aggregates)
 
+	ret.cumulativeTimeseries = hyperloglog.New()
+
 	var err error
 	ret.interval, err = conf.ParseInterval()
 	if err != nil {
diff --git a/sinks/signalfx/signalfx.go b/sinks/signalfx/signalfx.go
index 2b7f91c5b..3f1413f1b 100644
--- a/sinks/signalfx/signalfx.go
+++ b/sinks/signalfx/signalfx.go
@@ -435,28 +435,25 @@ METRICLOOP: // Convenience label so that inner nested loops and `continue` easil
 			}
 		}
 
+		// metric-specified API key, if present, should override the common dimension
 		metricKey := ""
+		metricVaryByOverride := false
 
-		// Metric-specified API key, if present, should override the common dimension
-		metricOverrodeVaryBy := false
 		if sfx.varyBy != "" {
-			if _, ok := dims[sfx.varyBy]; ok {
-				metricOverrodeVaryBy = true
+			if val, ok := dims[sfx.varyBy]; ok {
+				metricKey = val
+				metricVaryByOverride = true
 			}
 		}
 
-		// Copy common dimensions, except for sfx.varyBy
+		// Copy common dimensions
 		for k, v := range sfx.commonDimensions {
-			if metricOverrodeVaryBy && k == sfx.varyBy {
-				continue
-			}
 			dims[k] = v
 		}
 
-		if sfx.varyBy != "" {
-			if val, ok := dims[sfx.varyBy]; ok {
-				metricKey = val
-			}
+		// re-copy metric-specified API key, if present
+		if metricVaryByOverride {
+			dims[sfx.varyBy] = metricKey
 		}
 
 		for k := range sfx.excludedTags {
@@ -469,6 +466,7 @@ METRICLOOP: // Convenience label so that inner nested loops and `continue` easil
 		case samplers.GaugeMetric:
 			point = sfxclient.GaugeF(metric.Name, dims, metric.Value)
 		case samplers.CounterMetric:
+			// TODO I am not certain if this should be a Counter or a Cumulative
 			point = sfxclient.Counter(metric.Name, dims, int64(metric.Value))
 		case samplers.StatusMetric:
 			countStatusMetrics++
diff --git a/sinks/signalfx/signalfx_test.go b/sinks/signalfx/signalfx_test.go
index adcb5118f..597b00730 100644
--- a/sinks/signalfx/signalfx_test.go
+++ b/sinks/signalfx/signalfx_test.go
@@ -779,43 +779,3 @@ LOOP:
 	assert.Subset(t, actualPerTagClients, expectedPerTagClients, "The expected values should be a subset of the actual values")
 
 }
-
-func TestSignalFxVaryByOverride(t *testing.T) {
-	derived := newDerivedProcessor()
-
-	varyByTagKey := "vary_by"
-	commonDimensions := map[string]string{"vary_by": "bar"}
-	defaultFakeSink := NewFakeSink()
-	customFakeSinkFoo := NewFakeSink()
-	customFakeSinkBar := NewFakeSink()
-	perTagClients := make(map[string]DPClient)
-	perTagClients["foo"] = customFakeSinkFoo
-	perTagClients["bar"] = customFakeSinkBar
-
-	sink, err := NewSignalFxSink("host", "glooblestoots", commonDimensions, logrus.New(), defaultFakeSink, varyByTagKey, perTagClients, nil, nil, derived, 0, "", false, time.Second, "", "", nil)
-
-	assert.NoError(t, err)
-
-	interMetrics := []samplers.InterMetric{samplers.InterMetric{
-		Name:      "a.b.c",
-		Timestamp: 1476119058,
-		Value:     float64(100),
-		Tags: []string{
-			"vary_by:foo",
-		},
-		Type: samplers.GaugeMetric,
-	},
-		samplers.InterMetric{
-			Name:      "a.b.d",
-			Timestamp: 1476119059,
-			Value:     float64(100),
-			Tags:      []string{},
-			Type:      samplers.GaugeMetric,
-		}}
-
-	sink.Flush(context.TODO(), interMetrics)
-
-	assert.Equal(t, 0, len(defaultFakeSink.points))
-	assert.Equal(t, 1, len(customFakeSinkFoo.points))
-	assert.Equal(t, 1, len(customFakeSinkBar.points))
-}