From f4d098fb133adc1eddd9470ff3d819aff97d39f5 Mon Sep 17 00:00:00 2001
From: woodsaj <awoods@raintank.io>
Date: Thu, 21 Dec 2017 22:28:10 +0800
Subject: [PATCH] prune correctly when series is both leaf and branch

-  this issue was discovered in discussions of issue #714
-  this also fixes #797
---
 idx/memory/memory.go | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/idx/memory/memory.go b/idx/memory/memory.go
index 48ac7b1de2..a6a14d8705 100755
--- a/idx/memory/memory.go
+++ b/idx/memory/memory.go
@@ -1136,8 +1136,19 @@ func (m *MemoryIdx) Prune(orgId int, oldest time.Time) ([]idx.Archive, error) {
 			}
 
 			log.Debug("memory-idx: series %s for orgId:%d is stale. pruning it.", n.Path, org)
-			defs := m.delete(org, n, true)
-			statMetricsActive.Dec()
+			defs := make([]idx.Archive, 0)
+			if n.HasChildren() {
+				// this path is a leaf and branch node, so lets remove the defIds to make it just a branch.
+				for _, id := range n.Defs {
+					log.Debug("memory-idx: deleting %s from index", id)
+					defs = append(defs, *m.DefById[id])
+					delete(m.DefById, id)
+				}
+				n.Defs = []string{}
+			} else {
+				defs = m.delete(org, n, true)
+			}
+			statMetricsActive.Add(-1 * len(defs))
 			pruned = append(pruned, defs...)
 			m.Unlock()
 		}