From 0095d1d5839085cb2d299a0956a22e7b2958688f Mon Sep 17 00:00:00 2001
From: Martin Traverso <mtraverso@gmail.com>
Date: Thu, 22 Mar 2018 21:52:37 -0700
Subject: [PATCH] Fix bounds check in MultiChannelGroupByHash

There's an off-by-one error in the check that can
cause a failure when the page is empty
---
 .../com/facebook/presto/operator/MultiChannelGroupByHash.java   | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/presto-main/src/main/java/com/facebook/presto/operator/MultiChannelGroupByHash.java b/presto-main/src/main/java/com/facebook/presto/operator/MultiChannelGroupByHash.java
index 89860385324c..26f257c01bdd 100644
--- a/presto-main/src/main/java/com/facebook/presto/operator/MultiChannelGroupByHash.java
+++ b/presto-main/src/main/java/com/facebook/presto/operator/MultiChannelGroupByHash.java
@@ -632,7 +632,7 @@ public GetNonDictionaryGroupIdsWork(Page page)
         public boolean process()
         {
             int positionCount = page.getPositionCount();
-            checkState(lastPosition < positionCount, "position count out of bound");
+            checkState(lastPosition <= positionCount, "position count out of bound");
             checkState(!finished);
 
             // needRehash() == false indicates we have reached capacity boundary and a rehash is needed.