From 5ecd909f7c04527904cf3ec5b2575c3c6f69c210 Mon Sep 17 00:00:00 2001
From: fjy <fangjin@metamarkets.com>
Date: Mon, 16 Dec 2013 14:27:01 -0800
Subject: [PATCH] reduce NPEs in CQE

---
 .../java/io/druid/query/ChainedExecutionQueryRunner.java     | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/processing/src/main/java/io/druid/query/ChainedExecutionQueryRunner.java b/processing/src/main/java/io/druid/query/ChainedExecutionQueryRunner.java
index 8710b627ece..316c8d8675e 100644
--- a/processing/src/main/java/io/druid/query/ChainedExecutionQueryRunner.java
+++ b/processing/src/main/java/io/druid/query/ChainedExecutionQueryRunner.java
@@ -84,6 +84,11 @@ public class ChainedExecutionQueryRunner<T> implements QueryRunner<T>
   {
     final int priority = Integer.parseInt(query.getContextValue("priority", "0"));
 
+    if (Iterables.isEmpty(queryables)) {
+      log.warn("No queryables found.");
+      return Sequences.empty();
+    }
+
     return new BaseSequence<T, Iterator<T>>(
         new BaseSequence.IteratorMaker<T, Iterator<T>>()
         {