How to use

getFooter

method

in

io.prestosql.orc.OrcReader

private static Optional<OrcFileMetadata> getOrcFileMetadata(OrcReader reader)
{
  return Optional.ofNullable(reader.getFooter().getUserMetadata().get(OrcFileMetadata.KEY))
      .map(slice -> METADATA_CODEC.fromJson(slice.getBytes()));
}

private List<ColumnInfo> getColumnInfo(OrcReader reader)
{
  Optional<OrcFileMetadata> metadata = getOrcFileMetadata(reader);
  if (metadata.isPresent()) {
    return getColumnInfoFromOrcUserMetadata(metadata.get());
  }
  // support for legacy files without metadata
  return getColumnInfoFromOrcColumnTypes(reader.getColumnNames(), reader.getFooter().getTypes());
}

public void doIntegration(TestingOrcDataSource orcDataSource, DataSize maxMergeDistance, DataSize maxReadSize, DataSize tinyStripeThreshold)
    throws IOException
{
  OrcReader orcReader = new OrcReader(orcDataSource, ORC, maxMergeDistance, maxReadSize, tinyStripeThreshold, new DataSize(1, Unit.MEGABYTE));
  // 1 for reading file footer
  assertEquals(orcDataSource.getReadCount(), 1);
  List<StripeInformation> stripes = orcReader.getFooter().getStripes();
  // Sanity check number of stripes. This can be three or higher because of orc writer low memory mode.
  assertGreaterThanOrEqual(stripes.size(), 3);
  //verify wrapped by CachingOrcReader
  assertInstanceOf(wrapWithCacheIfTinyStripes(orcDataSource, stripes, maxMergeDistance, tinyStripeThreshold), CachingOrcDataSource.class);
  OrcRecordReader orcRecordReader = orcReader.createRecordReader(
      ImmutableMap.of(0, VARCHAR),
      (numberOfRows, statisticsByColumnIndex) -> true,
      HIVE_STORAGE_TIME_ZONE,
      newSimpleAggregatedMemoryContext(),
      INITIAL_BATCH_SIZE);
  int positionCount = 0;
  while (true) {
    int batchSize = orcRecordReader.nextBatch();
    if (batchSize <= 0) {
      break;
    }
    Block block = orcRecordReader.readBlock(VARCHAR, 0);
    positionCount += block.getPositionCount();
  }
  assertEquals(positionCount, POSITION_COUNT);
}

public void doIntegration(TestingOrcDataSource orcDataSource, DataSize maxMergeDistance, DataSize maxReadSize, DataSize tinyStripeThreshold)
    throws IOException
{
  OrcReader orcReader = new OrcReader(orcDataSource, ORC, maxMergeDistance, maxReadSize, tinyStripeThreshold, new DataSize(1, Unit.MEGABYTE));
  // 1 for reading file footer
  assertEquals(orcDataSource.getReadCount(), 1);
  List<StripeInformation> stripes = orcReader.getFooter().getStripes();
  // Sanity check number of stripes. This can be three or higher because of orc writer low memory mode.
  assertGreaterThanOrEqual(stripes.size(), 3);
  //verify wrapped by CachingOrcReader
  assertInstanceOf(wrapWithCacheIfTinyStripes(orcDataSource, stripes, maxMergeDistance, tinyStripeThreshold), CachingOrcDataSource.class);
  OrcRecordReader orcRecordReader = orcReader.createRecordReader(
      ImmutableMap.of(0, VARCHAR),
      (numberOfRows, statisticsByColumnIndex) -> true,
      HIVE_STORAGE_TIME_ZONE,
      newSimpleAggregatedMemoryContext(),
      INITIAL_BATCH_SIZE);
  int positionCount = 0;
  while (true) {
    int batchSize = orcRecordReader.nextBatch();
    if (batchSize <= 0) {
      break;
    }
    Block block = orcRecordReader.readBlock(VARCHAR, 0);
    positionCount += block.getPositionCount();
  }
  assertEquals(positionCount, POSITION_COUNT);
}

@Test
public void testReadUserMetadata()
    throws Exception
{
  try (TempFile tempFile = new TempFile()) {
    Map<String, String> metadata = ImmutableMap.of(
        "a", "ala",
        "b", "ma",
        "c", "kota");
    createFileWithOnlyUserMetadata(tempFile.getFile(), metadata);
    OrcDataSource orcDataSource = new FileOrcDataSource(tempFile.getFile(), new DataSize(1, MEGABYTE), new DataSize(1, MEGABYTE), new DataSize(1, MEGABYTE), true);
    OrcReader orcReader = new OrcReader(orcDataSource, ORC, new DataSize(1, MEGABYTE), new DataSize(1, MEGABYTE), new DataSize(1, MEGABYTE), new DataSize(1, MEGABYTE));
    Footer footer = orcReader.getFooter();
    Map<String, String> readMetadata = Maps.transformValues(footer.getUserMetadata(), Slice::toStringAscii);
    assertEquals(readMetadata, metadata);
  }
}

@Test
public void testReadUserMetadata()
    throws Exception
{
  try (TempFile tempFile = new TempFile()) {
    Map<String, String> metadata = ImmutableMap.of(
        "a", "ala",
        "b", "ma",
        "c", "kota");
    createFileWithOnlyUserMetadata(tempFile.getFile(), metadata);
    OrcDataSource orcDataSource = new FileOrcDataSource(tempFile.getFile(), new DataSize(1, MEGABYTE), new DataSize(1, MEGABYTE), new DataSize(1, MEGABYTE), true);
    OrcReader orcReader = new OrcReader(orcDataSource, ORC, new DataSize(1, MEGABYTE), new DataSize(1, MEGABYTE), new DataSize(1, MEGABYTE), new DataSize(1, MEGABYTE));
    Footer footer = orcReader.getFooter();
    Map<String, String> readMetadata = Maps.transformValues(footer.getUserMetadata(), Slice::toStringAscii);
    assertEquals(readMetadata, metadata);
  }
}

Footer footer = new OrcReader(orcDataSource, ORC, dataSize, dataSize, dataSize, dataSize).getFooter();

Footer footer = new OrcReader(orcDataSource, ORC, dataSize, dataSize, dataSize, dataSize).getFooter();