[SPARK-13537][SQL] Fix readBytes in VectorizedPlainValuesReader

JIRA: https://issues.apache.org/jira/browse/SPARK-13537

## What changes were proposed in this pull request?

In readBytes of VectorizedPlainValuesReader, we use buffer[offset] to access bytes in buffer. It is incorrect because offset is added with Platform.BYTE_ARRAY_OFFSET when initialization. We should fix it.

## How was this patch tested?

`ParquetHadoopFsRelationSuite` sometimes (depending on the randomly generated data) will be [failed](https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/52136/consoleFull) by this bug. After applying this, the test can be passed.

I added a test to `ParquetHadoopFsRelationSuite` with the data which will fail without this patch.

The error exception:

    [info] ParquetHadoopFsRelationSuite:
    [info] - test all data types - StringType (440 milliseconds)
    [info] - test all data types - BinaryType (434 milliseconds)
    [info] - test all data types - BooleanType (406 milliseconds)
    20:59:38.618 ERROR org.apache.spark.executor.Executor: Exception in task 0.0 in stage 2597.0 (TID 67966)
    java.lang.ArrayIndexOutOfBoundsException: 46
	at org.apache.spark.sql.execution.datasources.parquet.VectorizedPlainValuesReader.readBytes(VectorizedPlainValuesReader.java:88)

Author: Liang-Chi Hsieh <viirya@gmail.com>

Closes #11418 from viirya/fix-readbytes.

1 files changed, 1 insertions, 1 deletions

diff --git a/sql/core/src/main/java/org/apache/spark/sql/execution/datasources/parquet/VectorizedPlainValuesReader.java b/sql/core/src/main/java/org/apache/spark/sql/execution/datasources/parquet/VectorizedPlainValuesReader.java
index 57cc28e9f4..ee9a7a221b 100644
--- a/sql/core/src/main/java/org/apache/spark/sql/execution/datasources/parquet/VectorizedPlainValuesReader.java
+++ b/sql/core/src/main/java/org/apache/spark/sql/execution/datasources/parquet/VectorizedPlainValuesReader.java
@@ -85,7 +85,7 @@ public class VectorizedPlainValuesReader extends ValuesReader implements Vectori
     for (int i = 0; i < total; i++) {
       // Bytes are stored as a 4-byte little endian int. Just read the first byte.
       // TODO: consider pushing this in ColumnVector by adding a readBytes with a stride.
-      c.putByte(rowId + i, buffer[offset]);
+      c.putByte(rowId + i, Platform.getByte(buffer, offset));
       offset += 4;
     }
   }