From dd2da3bce5742a8ef796e9b770c6f6300dade91d Mon Sep 17 00:00:00 2001
From: "hao.peng" <hao.peng@smartx.com>
Date: Wed, 30 Oct 2024 16:49:39 +0800
Subject: [PATCH] app/vmselect/prometheus: remove stale NaN for range vector
 query

---
 app/vmselect/prometheus/prometheus.go | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/app/vmselect/prometheus/prometheus.go b/app/vmselect/prometheus/prometheus.go
index d608d4494..298140f55 100644
--- a/app/vmselect/prometheus/prometheus.go
+++ b/app/vmselect/prometheus/prometheus.go
@@ -12,6 +12,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/decimal"
 	"github.com/VictoriaMetrics/metrics"
 	"github.com/VictoriaMetrics/metricsql"
 	"github.com/valyala/fastjson/fastfloat"
@@ -22,7 +23,6 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmselect/searchutils"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bufferedwriter"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/decimal"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/encoding"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
@@ -312,6 +312,7 @@ func ExportHandler(startTime time.Time, w http.ResponseWriter, r *http.Request)
 var exportDuration = metrics.NewSummary(`vm_request_duration_seconds{path="/api/v1/export"}`)
 
 func exportHandler(qt *querytracer.Tracer, w http.ResponseWriter, cp *commonParams, format string, maxRowsPerLine int, reduceMemUsage bool) error {
+	var dropStale bool
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	sw := newScalableWriter(bw)
@@ -329,6 +330,7 @@ func exportHandler(qt *querytracer.Tracer, w http.ResponseWriter, cp *commonPara
 			return sw.maybeFlushBuffer(bb)
 		}
 	} else if format == "promapi" {
+		dropStale = true
 		WriteExportPromAPIHeader(bw)
 		var firstLineOnce atomic.Bool
 		var firstLineSent atomic.Bool
@@ -403,12 +405,17 @@ func exportHandler(qt *querytracer.Tracer, w http.ResponseWriter, cp *commonPara
 				}
 				xb := exportBlockPool.Get().(*exportBlock)
 				xb.mn = &rs.MetricName
-				for i, v := range rs.Values {
-					if decimal.IsStaleNaN(v) {
-						continue
+				if dropStale {
+					for i, v := range rs.Values {
+						if decimal.IsStaleNaN(v) {
+							continue
+						}
+						xb.values = append(xb.values, v)
+						xb.timestamps = append(xb.timestamps, rs.Timestamps[i])
 					}
-					xb.values = append(xb.values, v)
-					xb.timestamps = append(xb.timestamps, rs.Timestamps[i])
+				} else {
+					xb.timestamps = rs.Timestamps
+					xb.values = rs.Values
 				}
 				if err := writeLineFunc(xb, workerID); err != nil {
 					return err