From 698ccca6adc90a572fbadc4b3ccf26d92c300524 Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@gmail.com>
Date: Thu, 25 Mar 2021 18:38:49 +0200
Subject: [PATCH] app/vmselect/prometheus: explain why partial responses are
 disallowed during data export

See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1148
---
 app/vmselect/prometheus/prometheus.go | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/app/vmselect/prometheus/prometheus.go b/app/vmselect/prometheus/prometheus.go
index 5b2fdc451..c7b4bf43e 100644
--- a/app/vmselect/prometheus/prometheus.go
+++ b/app/vmselect/prometheus/prometheus.go
@@ -365,6 +365,8 @@ func exportHandler(at *auth.Token, w http.ResponseWriter, r *http.Request, match
 	resultsCh := make(chan *quicktemplate.ByteBuffer, cgroup.AvailableCPUs())
 	doneCh := make(chan error)
 	if !reduceMemUsage {
+		// Unconditionally deny partial response for the exported data,
+		// since users usually expect that the exported data is full.
 		denyPartialResponse := true
 		rss, _, err := netstorage.ProcessSearchQuery(at, denyPartialResponse, sq, true, deadline)
 		if err != nil {