app/vmselect: fixes graphite function transformRemoveEmptySeries

Previously it incorrectly applied xFilesFactor, if it's value equal to 0.

 This commit properly handles this case and returns result according to
the graphite documentation:
  
`xFilesFactor follows the same semantics as in Whisper storage schemas. Setting it to 0 (the default) means that only a single value in the series needs to be non-null for it to be considered non-empty, setting it to 1 means that all values ​​in the series must be non-null. A setting of 0.5 means that at least half the values ​​in the series must be non-null.`

Signed-off-by: f41gh7 <nik@victoriametrics.com>
Co-authored-by: Evgeniy Negriy <einegriy@avito.ru>

app/vmselect/graphite/eval_test.go

@@ -2137,6 +2137,25 @@ func TestExecExprSuccess(t *testing.T) {
 		},
 	})
 	f(`removeEmptySeries(removeBelowValue(time('a'),150),1)`, []*series{})
+	// if xFilesFactor is set, a single value in the series needs to be non-null for it to be
+	// considered non-empty
+	f(`removeEmptySeries(removeBelowValue(time('a'),150),0)`, []*series{
+		{
+			Timestamps: []int64{120000, 180000},
+			Values:     []float64{nan, 180},
+			Name:       "removeBelowValue(a,150)",
+			Tags:       map[string]string{"name": "a"},
+		},
+	})
+	f(`removeEmptySeries(removeBelowValue(time('a'),150),-1)`, []*series{
+		{
+			Timestamps: []int64{120000, 180000},
+			Values:     []float64{nan, 180},
+			Name:       "removeBelowValue(a,150)",
+			Tags:       map[string]string{"name": "a"},
+		},
+	})
+
 	f(`round(time('a',17),-1)`, []*series{
 		{
 			Timestamps:     []int64{120000, 137000, 154000, 171000, 188000, 205000},

app/vmselect/graphite/transform.go

@@ -3151,7 +3151,7 @@ func transformRemoveEmptySeries(ec *evalConfig, fe *graphiteql.FuncExpr) (nextSe
 			xff = xFilesFactor
 		}
 		n := aggrCount(s.Values)
-		if n/float64(len(s.Values)) < xff {
+		if n/float64(len(s.Values)) <= xff {
 			return nil, nil
 		}
 		s.expr = fe

docs/changelog/CHANGELOG.md

@@ -20,6 +20,7 @@ See also [LTS releases](https://docs.victoriametrics.com/lts-releases/).
 
 * BUGFIX: [vmctl](https://docs.victoriametrics.com/vmctl/): drop rows that do not belong to the current series during import. The dropped rows should belong to another series whose tags are a superset of the current series. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/7301) and [this pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/7330). Thanks to @dpedu for reporting and cooperating with the test.
 * BUGFIX: [vmsingle](https://docs.victoriametrics.com/single-server-victoriametrics/), `vmselect` in [VictoriaMetrics cluster](https://docs.victoriametrics.com/cluster-victoriametrics/): keep the order of resulting time series when `limit_offset` is applied. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/7068).
+* BUGFIX: [graphite](https://docs.victoriametrics.com/#graphite-render-api-usage): properly handle xFilesFactor=0 for `transformRemoveEmptySeries` function. See [this PR](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/7337) for details.
 
 ## [v1.106.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.106.0)