From 4ef7158e897f7bab5c136d0589e715c44bc9691c Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@gmail.com>
Date: Wed, 2 Dec 2020 00:28:16 +0200
Subject: [PATCH] app/vmselect/promql: return `nan` from `a >bool b` if `a` is
 `nan` in the same way as Prometheus does

---
 app/vmselect/promql/binary_op.go |  3 +++
 app/vmselect/promql/exec_test.go | 26 ++++++++++++++++++++++++--
 docs/CHANGELOG.md                |  2 ++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/app/vmselect/promql/binary_op.go b/app/vmselect/promql/binary_op.go
index d26282330..7d827607a 100644
--- a/app/vmselect/promql/binary_op.go
+++ b/app/vmselect/promql/binary_op.go
@@ -62,6 +62,9 @@ func newBinaryOpCmpFunc(cf func(left, right float64) bool) binaryOpFunc {
 		if cf(left, right) {
 			return 1
 		}
+		if math.IsNaN(left) {
+			return nan
+		}
 		return 0
 	}
 	return newBinaryOpFunc(cfe)
diff --git a/app/vmselect/promql/exec_test.go b/app/vmselect/promql/exec_test.go
index 1aac301db..d0cccb5ec 100644
--- a/app/vmselect/promql/exec_test.go
+++ b/app/vmselect/promql/exec_test.go
@@ -1782,10 +1782,32 @@ func TestExecSuccess(t *testing.T) {
 	})
 	t.Run(`time() > scalar`, func(t *testing.T) {
 		t.Parallel()
-		q := `time() > 123`
+		q := `time() > 1234`
 		r := netstorage.Result{
 			MetricName: metricNameExpected,
-			Values:     []float64{1000, 1200, 1400, 1600, 1800, 2000},
+			Values:     []float64{nan, nan, 1400, 1600, 1800, 2000},
+			Timestamps: timestampsExpected,
+		}
+		resultExpected := []netstorage.Result{r}
+		f(q, resultExpected)
+	})
+	t.Run(`time() >bool scalar`, func(t *testing.T) {
+		t.Parallel()
+		q := `time() >bool 1234`
+		r := netstorage.Result{
+			MetricName: metricNameExpected,
+			Values:     []float64{0, 0, 1, 1, 1, 1},
+			Timestamps: timestampsExpected,
+		}
+		resultExpected := []netstorage.Result{r}
+		f(q, resultExpected)
+	})
+	t.Run(`nan >bool scalar1`, func(t *testing.T) {
+		t.Parallel()
+		q := `(time() > 1234) >bool 1450`
+		r := netstorage.Result{
+			MetricName: metricNameExpected,
+			Values:     []float64{nan, nan, 0, 1, 1, 1},
 			Timestamps: timestampsExpected,
 		}
 		resultExpected := []netstorage.Result{r}
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index b26e74778..1354d263e 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -4,6 +4,8 @@
 
 * BUGFIX: properly parse timestamps in OpenMetrics format - they are exposed as floating-point number in seconds instead of integer milliseconds
   unlike in Prometheus exposition format. See [the docs](https://github.com/OpenObservability/OpenMetrics/blob/master/specification/OpenMetrics.md#timestamps).
+* BUGFIX: return `nan` for `a >bool b` query when `a` equals to `nan` like Prometheus does. Previously `0` was returned in this case. This applies to any comparison operation
+  with `bool` modifier. See [these docs](https://prometheus.io/docs/prometheus/latest/querying/operators/#comparison-binary-operators) for details.
 
 
 # [v1.48.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.48.0)