[SPARK-12589][SQL] Fix UnsafeRowParquetRecordReader to properly set the row length.

The reader was previously not setting the row length meaning it was wrong if there were variable
length columns. This problem does not manifest usually, since the value in the column is correct and
projecting the row fixes the issue.

Author: Nong Li <[email protected]>

Closes apache#10576 from nongli/spark-12589.

Author: nongli

sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeRow.java

@@ -177,6 +177,10 @@ public void pointTo(byte[] buf, int sizeInBytes) {
     pointTo(buf, Platform.BYTE_ARRAY_OFFSET, sizeInBytes);
   }
 
+  public void setTotalSize(int sizeInBytes) {
+    this.sizeInBytes = sizeInBytes;
+  }
+
   public void setNotNullAt(int i) {
     assertIndexIsValid(i);
     BitSetMethods.unset(baseObject, baseOffset, i);

sql/core/src/main/java/org/apache/spark/sql/execution/datasources/parquet/UnsafeRowParquetRecordReader.java

@@ -256,6 +256,15 @@ private boolean loadBatch() throws IOException {
       numBatched = num;
       batchIdx = 0;
     }
+
+    // Update the total row lengths if the schema contained variable length. We did not maintain
+    // this as we populated the columns.
+    if (containsVarLenFields) {
+      for (int i = 0; i < numBatched; ++i) {
+        rows[i].setTotalSize(rowWriters[i].holder().totalSize());
+      }
+    }
+
     return true;
   }
 

sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetIOSuite.scala

@@ -38,6 +38,7 @@ import org.apache.parquet.schema.{MessageType, MessageTypeParser}
 import org.apache.spark.SparkException
 import org.apache.spark.sql._
 import org.apache.spark.sql.catalyst.ScalaReflection
+import org.apache.spark.sql.catalyst.expressions.UnsafeRow
 import org.apache.spark.sql.catalyst.util.DateTimeUtils
 import org.apache.spark.sql.test.SharedSQLContext
 import org.apache.spark.sql.types._
@@ -618,6 +619,29 @@ class ParquetIOSuite extends QueryTest with ParquetTest with SharedSQLContext {
       readResourceParquetFile("dec-in-fixed-len.parquet"),
       sqlContext.range(1 << 4).select('id % 10 cast DecimalType(10, 2) as 'fixed_len_dec))
   }
+
+  test("SPARK-12589 copy() on rows returned from reader works for strings") {
+    withTempPath { dir =>
+      val data = (1, "abc") ::(2, "helloabcde") :: Nil
+      data.toDF().write.parquet(dir.getCanonicalPath)
+      var hash1: Int = 0
+      var hash2: Int = 0
+      (false :: true :: Nil).foreach { v =>
+        withSQLConf(SQLConf.PARQUET_UNSAFE_ROW_RECORD_READER_ENABLED.key -> v.toString) {
+          val df = sqlContext.read.parquet(dir.getCanonicalPath)
+          val rows = df.queryExecution.toRdd.map(_.copy()).collect()
+          val unsafeRows = rows.map(_.asInstanceOf[UnsafeRow])
+          if (!v) {
+            hash1 = unsafeRows(0).hashCode()
+            hash2 = unsafeRows(1).hashCode()
+          } else {
+            assert(hash1 == unsafeRows(0).hashCode())
+            assert(hash2 == unsafeRows(1).hashCode())
+          }
+        }
+      }
+    }
+  }
 }
 
 class JobCommitFailureParquetOutputCommitter(outputPath: Path, context: TaskAttemptContext)