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[jira] [Created] (ARROW-3175) Arrow Java: Upgrade to official FlatBuffers release (Flatbuffers incompatibility)


Alex Black created ARROW-3175:
---------------------------------

             Summary: Arrow Java: Upgrade to official FlatBuffers release (Flatbuffers incompatibility)
                 Key: ARROW-3175
                 URL: https://issues.apache.org/jira/browse/ARROW-3175
             Project: Apache Arrow
          Issue Type: Bug
          Components: Java
    Affects Versions: 0.10.0
            Reporter: Alex Black


Arrow Java currently uses an unofficial flatbuffers dependency - com.vlkan:flatbuffers:
 [https://github.com/apache/arrow/blob/master/java/pom.xml#L481-L485]

The likely motivation here is that previously, no Java flatbuffers implementation was available on maven central.
 [https://github.com/vy/flatbuffers]
 > Unfortunately, FlatBuffers project does not publish any artifacts to the Maven Central Repository

However, this is no longer the case:
 [https://search.maven.org/search?q=g:com.google.flatbuffers%20AND%20a:flatbuffers-java&core=gav]

The flatbuffers version used in Arrow java is a nearly 3-year-old snapshot, not even a version of an official release: [https://github.com/vy/flatbuffers#usage]

The main problem is that this version of flatbuffers is not compatible with the official releases of flatbuffers.
 For example, we use the official flatbuffers releases in ND4J and Deeplearning4j: [https://github.com/deeplearning4j/deeplearning4j]

Running Arrow with an official flatbuffers library on the classpath results in issues such as:
{noformat}
java.lang.NoSuchMethodError: com.google.flatbuffers.FlatBufferBuilder.createString(Ljava/lang/String;)I
 at org.apache.arrow.vector.types.pojo.Field.getField(Field.java:154)
 at org.apache.arrow.vector.types.pojo.Schema.getSchema(Schema.java:145)
 at org.apache.arrow.vector.ipc.message.MessageSerializer.serialize(MessageSerializer.java:124)
 at org.apache.arrow.vector.ipc.ArrowWriter.ensureStarted(ArrowWriter.java:136)
 at org.apache.arrow.vector.ipc.ArrowWriter.start(ArrowWriter.java:97)
 at FlatBuffersDependencyIssue.test(FlatBuffersDependencyIssue.java:56)
{noformat}
 

Simply excluding the com.vlkan:flatbuffers dependency in lieu of an official flatbuffers release is not a solution (same exception as above) and we aren't prepared to downgrade all of our projects to use the flatbuffers version that Arrow currently requires.
 Consequently, this is a major issue that prevents us using Arrow in our libraries.

I have prepared a simple repository to reproduce this issue, if required: [https://github.com/AlexDBlack/arrowflatbufferstest]

Is there a reason for using this particular version of flatbuffers, and if not, can Arrow java use an official release of flatbuffers instead?



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