@Test
  public void testUnionAndTimestamp() throws Exception {
    List<OrcProto.Type> types = new ArrayList<OrcProto.Type>();
    types.add(OrcProto.Type.newBuilder().setKind(OrcProto.Type.Kind.STRUCT).
        addFieldNames("time").addFieldNames("union").addFieldNames("decimal").
        addSubtypes(1).addSubtypes(2).addSubtypes(5).build());
    types.add(OrcProto.Type.newBuilder().setKind(OrcProto.Type.Kind.TIMESTAMP).
        build());
    types.add(OrcProto.Type.newBuilder().setKind(OrcProto.Type.Kind.UNION).
        addSubtypes(3).addSubtypes(4).build());
    types.add(OrcProto.Type.newBuilder().setKind(OrcProto.Type.Kind.INT).
        build());
    types.add(OrcProto.Type.newBuilder().setKind(OrcProto.Type.Kind.STRING).
        build());
    types.add(OrcProto.Type.newBuilder().setKind(OrcProto.Type.Kind.DECIMAL).
        build());

    ObjectInspector inspector;
    synchronized (TestOrcFile.class) {
      inspector = OrcStruct.createObjectInspector(0, types);
    }
    HiveDecimal maxValue = HiveDecimal.create("10000000000000000000");
    Writer writer = OrcFile.createWriter(testFilePath,
                                         OrcFile.writerOptions(conf)
                                         .inspector(inspector)
                                         .stripeSize(1000)
                                         .compress(CompressionKind.NONE)
                                         .batchSize(1000)
                                         .bufferSize(100)
                                         .blockPadding(false));
    OrcStruct row = new OrcStruct(3);
    OrcUnion union = new OrcUnion();
    row.setFieldValue(1, union);
    row.setFieldValue(0, new TimestampWritableV2(Timestamp.valueOf("2000-03-12 15:00:00")));
    HiveDecimal value = HiveDecimal.create("12345678.6547456");
    row.setFieldValue(2, new HiveDecimalWritable(value));
    union.set((byte) 0, new IntWritable(42));
    writer.addRow(row);
    row.setFieldValue(0, new TimestampWritableV2(Timestamp.valueOf("2000-03-20 12:00:00.123456789")));
    union.set((byte) 1, new Text("hello"));
    value = HiveDecimal.create("-5643.234");
    row.setFieldValue(2, new HiveDecimalWritable(value));
    writer.addRow(row);
    row.setFieldValue(0, null);
    row.setFieldValue(1, null);
    row.setFieldValue(2, null);
    writer.addRow(row);
    row.setFieldValue(1, union);
    union.set((byte) 0, null);
    writer.addRow(row);
    union.set((byte) 1, null);
    writer.addRow(row);
    union.set((byte) 0, new IntWritable(200000));
    row.setFieldValue(0, new TimestampWritableV2
        (Timestamp.valueOf("1970-01-01 00:00:00")));
    value = HiveDecimal.create("10000000000000000000");
    row.setFieldValue(2, new HiveDecimalWritable(value));
    writer.addRow(row);
    Random rand = new Random(42);
    for(int i=1970; i < 2038; ++i) {
      row.setFieldValue(0, new TimestampWritableV2(Timestamp.valueOf(i +
          "-05-05 12:34:56." + i)));
      if ((i & 1) == 0) {
        union.set((byte) 0, new IntWritable(i*i));
      } else {
        union.set((byte) 1, new Text(Integer.toString(i * i)));
      }
      value = HiveDecimal.create(new BigInteger(64, rand),
          rand.nextInt(18));
      row.setFieldValue(2, new HiveDecimalWritable(value));
      if (maxValue.compareTo(value) < 0) {
        maxValue = value;
      }
      writer.addRow(row);
    }
    // let's add a lot of constant rows to test the rle
    row.setFieldValue(0, null);
    union.set((byte) 0, new IntWritable(1732050807));
    row.setFieldValue(2, null);
    for(int i=0; i < 5000; ++i) {
      writer.addRow(row);
    }
    union.set((byte) 0, new IntWritable(0));
    writer.addRow(row);
    union.set((byte) 0, new IntWritable(10));
    writer.addRow(row);
    union.set((byte) 0, new IntWritable(138));
    writer.addRow(row);
    writer.close();
    Reader reader = OrcFile.createReader(testFilePath,
        OrcFile.readerOptions(conf).filesystem(fs));

    TypeDescription schema = writer.getSchema();
    assertEquals(5, schema.getMaximumId());
    boolean[] expected = new boolean[] {false, false, false, false, false, false};
    boolean[] included = OrcUtils.includeColumns("", schema);
    assertEquals(true, Arrays.equals(expected, included));

    expected = new boolean[] {false, true, false, false, false, true};
    included = OrcUtils.includeColumns("time,decimal", schema);
    assertEquals(true, Arrays.equals(expected, included));

    expected = new boolean[] {false, false, true, true, true, false};
    included = OrcUtils.includeColumns("union", schema);
    assertEquals(true, Arrays.equals(expected, included));

    assertEquals(false, reader.getMetadataKeys().iterator().hasNext());
    assertEquals(5077, reader.getNumberOfRows());
    DecimalColumnStatistics stats =
        (DecimalColumnStatistics) reader.getStatistics()[5];
    assertEquals(71, stats.getNumberOfValues());
    assertEquals(HiveDecimal.create("-5643.234"), stats.getMinimum());
    assertEquals(maxValue, stats.getMaximum());
    // TODO: fix this
//    assertEquals(null,stats.getSum());
    int stripeCount = 0;
    int rowCount = 0;
    long currentOffset = -1;
    for(StripeInformation stripe: reader.getStripes()) {
      stripeCount += 1;
      rowCount += stripe.getNumberOfRows();
      if (currentOffset < 0) {
        currentOffset = stripe.getOffset() + stripe.getLength();
      } else {
        assertEquals(currentOffset, stripe.getOffset());
        currentOffset += stripe.getLength();
      }
    }
    assertEquals(reader.getNumberOfRows(), rowCount);
    assertEquals(2, stripeCount);
    assertEquals(reader.getContentLength(), currentOffset);
    RecordReader rows = reader.rows();
    assertEquals(0, rows.getRowNumber());
    assertEquals(0.0, rows.getProgress(), 0.000001);
    assertEquals(true, rows.hasNext());
    row = (OrcStruct) rows.next(null);
    assertEquals(1, rows.getRowNumber());
    inspector = reader.getObjectInspector();
    assertEquals("struct<time:timestamp,union:uniontype<int,string>,decimal:decimal(38,18)>",
        inspector.getTypeName());
    assertEquals(new TimestampWritableV2(Timestamp.valueOf("2000-03-12 15:00:00")),
        row.getFieldValue(0));
    union = (OrcUnion) row.getFieldValue(1);
    assertEquals(0, union.getTag());
    assertEquals(new IntWritable(42), union.getObject());
    assertEquals(new HiveDecimalWritable(HiveDecimal.create("12345678.6547456")),
        row.getFieldValue(2));
    row = (OrcStruct) rows.next(row);
    assertEquals(2, rows.getRowNumber());
    assertEquals(new TimestampWritableV2(Timestamp.valueOf("2000-03-20 12:00:00.123456789")),
        row.getFieldValue(0));
    assertEquals(1, union.getTag());
    assertEquals(new Text("hello"), union.getObject());
    assertEquals(new HiveDecimalWritable(HiveDecimal.create("-5643.234")),
        row.getFieldValue(2));
    row = (OrcStruct) rows.next(row);
    assertEquals(null, row.getFieldValue(0));
    assertEquals(null, row.getFieldValue(1));
    assertEquals(null, row.getFieldValue(2));
    row = (OrcStruct) rows.next(row);
    assertEquals(null, row.getFieldValue(0));
    union = (OrcUnion) row.getFieldValue(1);
    assertEquals(0, union.getTag());
    assertEquals(null, union.getObject());
    assertEquals(null, row.getFieldValue(2));
    row = (OrcStruct) rows.next(row);
    assertEquals(null, row.getFieldValue(0));
    assertEquals(1, union.getTag());
    assertEquals(null, union.getObject());
    assertEquals(null, row.getFieldValue(2));
    row = (OrcStruct) rows.next(row);
    assertEquals(new TimestampWritableV2(Timestamp.valueOf("1970-01-01 00:00:00")),
        row.getFieldValue(0));
    assertEquals(new IntWritable(200000), union.getObject());
    assertEquals(new HiveDecimalWritable(HiveDecimal.create("10000000000000000000")),
                 row.getFieldValue(2));
    rand = new Random(42);
    for(int i=1970; i < 2038; ++i) {
      row = (OrcStruct) rows.next(row);
      assertEquals(new TimestampWritableV2(Timestamp.valueOf(i + "-05-05 12:34:56." + i)),
          row.getFieldValue(0));
      if ((i & 1) == 0) {
        assertEquals(0, union.getTag());
        assertEquals(new IntWritable(i*i), union.getObject());
      } else {
        assertEquals(1, union.getTag());
        assertEquals(new Text(Integer.toString(i * i)), union.getObject());
      }
      assertEquals(new HiveDecimalWritable(HiveDecimal.create(new BigInteger(64, rand),
                                   rand.nextInt(18))), row.getFieldValue(2));
    }
    for(int i=0; i < 5000; ++i) {
      row = (OrcStruct) rows.next(row);
      assertEquals(new IntWritable(1732050807), union.getObject());
    }
    row = (OrcStruct) rows.next(row);
    assertEquals(new IntWritable(0), union.getObject());
    row = (OrcStruct) rows.next(row);
    assertEquals(new IntWritable(10), union.getObject());
    row = (OrcStruct) rows.next(row);
    assertEquals(new IntWritable(138), union.getObject());
    assertEquals(false, rows.hasNext());
    assertEquals(1.0, rows.getProgress(), 0.00001);
    assertEquals(reader.getNumberOfRows(), rows.getRowNumber());
    rows.seekToRow(1);
    row = (OrcStruct) rows.next(row);
    assertEquals(new TimestampWritableV2(Timestamp.valueOf("2000-03-20 12:00:00.123456789")),
        row.getFieldValue(0));
    assertEquals(1, union.getTag());
    assertEquals(new Text("hello"), union.getObject());
    assertEquals(new HiveDecimalWritable(HiveDecimal.create("-5643.234")), row.getFieldValue(2));
    rows.close();
  }
We test union, timestamp, and decimal separately since we need to make the
object inspector manually. (The Hive reflection-based doesn't handle
them properly.)
ql/src/test/org/apache/hadoop/hive/ql/io/orc/TestOrcFile.java