Apache Arrow Java API Documentation [closed]

Question

I am looking for useful documentations or examples for the Apache Arrow API. Can anyone point to some useful resources? I was only able to find some blogs and JAVA documentation (which doesn't say much).

From what I read, it is a standard in-memory columnar database for fast analytics. Is it possible to load the data to arrow memory and to manipulate it ?

Benge

Asking for off-site resources is off-topic for Stack Overflow. – Uncharitable

Answer 1

You should use arrow as a middle man between two applications which need to communicate using passing objects.

Arrow isn’t a standalone piece of software but rather a component used to accelerate analytics within a particular system and to allow Arrow-enabled systems to exchange data with low overhead.

For example Arrow improves the performance for data movement within a cluster.

See tests for examples.

  @Test
  public void test() throws Exception {
    BufferAllocator allocator = new RootAllocator(Integer.MAX_VALUE);
    File testInFile = testFolder.newFile("testIn.arrow");
    File testOutFile = testFolder.newFile("testOut.arrow");

    writeInput(testInFile, allocator);

    String[] args = {"-i", testInFile.getAbsolutePath(), "-o", testOutFile.getAbsolutePath()};
    int result = new FileRoundtrip(System.out, System.err).run(args);
    assertEquals(0, result);

    validateOutput(testOutFile, allocator);
}

Also Apache Parquet uses it. There are conversion examples from/to arrow objects:

MessageType parquet = converter.fromArrow(allTypesArrowSchema).getParquetSchema();

Schema arrow = converter.fromParquet(supportedTypesParquetSchema).getArrowSchema();

Unutterable

The linked test example isn't very informative. It isn't immediately obvious what a BufferAllocator or RootAllocator is. There isn't any evidence of "manipulating data" either... – Alidia

The converter included in Parquet's github repo seems to rely on Arrow 0.1.0 (and I can't get it to work, I get ClassNotFoundException when doing new SchemaConverter(), though I may be doing something wrong when installing it, as I could not find any published artifact for parquet-arrow) – Inofficious

Answer 2

They have some basic documentation on how to use Apache Arrow on their site now. Although it could use a bit of filling out.

Multifarious