From bba07d05fed688e6a33133be7ade08c172175ce9 Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@gmail.com>
Date: Thu, 4 Jul 2019 19:19:32 +0300
Subject: [PATCH] app/vmselect/promql: remove empty timeseries left after
 `topk` call

---
 app/vmselect/promql/aggr.go      |  2 +-
 app/vmselect/promql/exec_test.go | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/app/vmselect/promql/aggr.go b/app/vmselect/promql/aggr.go
index 2890ef349d..2732fb029b 100644
--- a/app/vmselect/promql/aggr.go
+++ b/app/vmselect/promql/aggr.go
@@ -431,7 +431,7 @@ func newAggrFuncTopK(isReverse bool) aggrFunc {
 					ts.Values[n] = nan
 				}
 			}
-			return rvs
+			return removeNaNs(rvs)
 		}
 		return aggrFuncExt(afe, args[1], &afa.ae.Modifier, true)
 	}
diff --git a/app/vmselect/promql/exec_test.go b/app/vmselect/promql/exec_test.go
index 8f702c122e..a21fc56bec 100644
--- a/app/vmselect/promql/exec_test.go
+++ b/app/vmselect/promql/exec_test.go
@@ -2483,6 +2483,21 @@ func TestExecSuccess(t *testing.T) {
 		resultExpected := []netstorage.Result{r1, r2}
 		f(q, resultExpected)
 	})
+	t.Run(`topk(1, nan_timeseries)`, func(t *testing.T) {
+		t.Parallel()
+		q := `topk(1, label_set(NaN, "foo", "bar") or label_set(time()/150, "baz", "sss")) default 0`
+		r1 := netstorage.Result{
+			MetricName: metricNameExpected,
+			Values:     []float64{6.666666666666667, 8, 9.333333333333334, 10.666666666666666, 12, 13.333333333333334},
+			Timestamps: timestampsExpected,
+		}
+		r1.MetricName.Tags = []storage.Tag{{
+			Key:   []byte("baz"),
+			Value: []byte("sss"),
+		}}
+		resultExpected := []netstorage.Result{r1}
+		f(q, resultExpected)
+	})
 	t.Run(`topk(2)`, func(t *testing.T) {
 		t.Parallel()
 		q := `sort(topk(2, label_set(10, "foo", "bar") or label_set(time()/150, "baz", "sss")))`