From a1087ed37a56491e36266e9bb619a9707d5b0000 Mon Sep 17 00:00:00 2001
From: Ganesh Vernekar <15064823+codesome@users.noreply.github.com>
Date: Thu, 1 Jul 2021 18:19:04 +0530
Subject: [PATCH] Fix scraping of sparse histograms (#9031)

Signed-off-by: Ganesh Vernekar <ganeshvern@gmail.com>
---
 storage/remote/write.go | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/storage/remote/write.go b/storage/remote/write.go
index 7d8f57d96..5eab6e919 100644
--- a/storage/remote/write.go
+++ b/storage/remote/write.go
@@ -15,7 +15,6 @@ package remote
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"sync"
 	"time"
@@ -220,6 +219,7 @@ type timestampTracker struct {
 	writeStorage         *WriteStorage
 	samples              int64
 	exemplars            int64
+	histograms           int64
 	highestTimestamp     int64
 	highestRecvTimestamp *maxTimestamp
 }
@@ -238,8 +238,12 @@ func (t *timestampTracker) AppendExemplar(_ uint64, _ labels.Labels, _ exemplar.
 	return 0, nil
 }
 
-func (t *timestampTracker) AppendHistogram(_ uint64, _ labels.Labels, _ int64, _ histogram.SparseHistogram) (uint64, error) {
-	return 0, errors.New("not implemented")
+func (t *timestampTracker) AppendHistogram(_ uint64, _ labels.Labels, ts int64, _ histogram.SparseHistogram) (uint64, error) {
+	t.histograms++
+	if ts > t.highestTimestamp {
+		t.highestTimestamp = ts
+	}
+	return 0, nil
 }
 
 // Commit implements storage.Appender.