From 48e39068bdf699501d304d26305a767e87a16c34 Mon Sep 17 00:00:00 2001
From: Tom Wilkie <tom.wilkie@gmail.com>
Date: Thu, 25 Jan 2018 11:11:55 +0000
Subject: [PATCH] Don't allocate a mergeSeries if there is only one series to
 merge.

---
 storage/fanout.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/storage/fanout.go b/storage/fanout.go
index ae74ad2ca..dd33999eb 100644
--- a/storage/fanout.go
+++ b/storage/fanout.go
@@ -340,6 +340,9 @@ func (c *mergeSeriesSet) Next() bool {
 }
 
 func (c *mergeSeriesSet) At() Series {
+	if len(c.currentSets) == 1 {
+		return c.currentSets[0].At()
+	}
 	series := []Series{}
 	for _, seriesSet := range c.currentSets {
 		series = append(series, seriesSet.At())