From b05dbff337945030bec61872cbfa23f4b563f441 Mon Sep 17 00:00:00 2001
From: Cheng Lian <lian@databricks.com>
Date: Sun, 1 Mar 2015 17:33:34 +0800
Subject: [PATCH] Provides better error message for malformed rows when caching
 tables

---
 .../sql/columnar/InMemoryColumnarTableScan.scala      | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/sql/core/src/main/scala/org/apache/spark/sql/columnar/InMemoryColumnarTableScan.scala b/sql/core/src/main/scala/org/apache/spark/sql/columnar/InMemoryColumnarTableScan.scala
index 11d5943fb427..8944a32bc388 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/columnar/InMemoryColumnarTableScan.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/columnar/InMemoryColumnarTableScan.scala
@@ -119,6 +119,17 @@ private[sql] case class InMemoryRelation(
           var rowCount = 0
           while (rowIterator.hasNext && rowCount < batchSize) {
             val row = rowIterator.next()
+
+            // Added for SPARK-6082. This assertion can be useful for scenarios when something
+            // like Hive TRANSFORM is used. The external data generation script used in TRANSFORM
+            // may result malformed rows, causing ArrayIndexOutOfBoundsException, which is somewhat
+            // hard to decipher.
+            assert(
+              row.size == columnBuilders.size,
+              s"""Row column number mismatch, expected ${output.size} columns, but got ${row.size}.
+                 |Row content: $row
+               """.stripMargin)
+
             var i = 0
             while (i < row.length) {
               columnBuilders(i).appendFrom(row, i)