[jira] [Created] (PARQUET-952) Avro union with single type fails with 'is not a group'

["Jarek Jarcec Cecho (JIRA)" <ji...@apache.org>]

Jarek Jarcec Cecho created PARQUET-952:
------------------------------------------

             Summary: Avro union with single type fails with 'is not a group'
                 Key: PARQUET-952
                 URL: https://issues.apache.org/jira/browse/PARQUET-952
             Project: Parquet
          Issue Type: Bug
            Reporter: Jarek Jarcec Cecho


When one uses Avro schema with a union that has only one type specified, the {{AvroParquetWriter}} throws an exception. See the following repro test case:

{code}
  @Test
  public void reproCase() throws Exception {
    System.out.println("Parquet version: " + Version.FULL_VERSION);

    // Schema with a single field 'value' with type of union that have a single item (=string)
    Schema avroSchema = Schema.parse("{" +
      "\"type\": \"record\", " +
      "\"name\": \"RandomRecord\", " +
      "\"fields\": [" +
      "{\"name\": \"value\", \"type\": [\"string\"] }" +
      "]" +
      "}");

    // Parquet writer
    ParquetWriter parquetWriter = AvroParquetWriter.builder(path).withSchema(avroSchema)
      .withConf(new Configuration())
      .build();

    GenericRecord record = new GenericRecordBuilder(avroSchema)
      .set("value", "Surprise!")
      .build();

    parquetWriter.write(record);
  }
{code}

Will result in:

{code}
Parquet version: parquet-mr version 1.9.0 (build 38262e2c80015d0935dad20f8e18f2d6f9fbd03c)

java.lang.ClassCastException: required binary value (UTF8) is not a group

	at org.apache.parquet.schema.Type.asGroupType(Type.java:202)
	at org.apache.parquet.avro.AvroWriteSupport.writeValueWithoutConversion(AvroWriteSupport.java:357)
	at org.apache.parquet.avro.AvroWriteSupport.writeValue(AvroWriteSupport.java:274)
	at org.apache.parquet.avro.AvroWriteSupport.writeRecordFields(AvroWriteSupport.java:187)
	at org.apache.parquet.avro.AvroWriteSupport.write(AvroWriteSupport.java:161)
	at org.apache.parquet.hadoop.InternalParquetRecordWriter.write(InternalParquetRecordWriter.java:123)
	at org.apache.parquet.hadoop.ParquetWriter.write(ParquetWriter.java:292)
	at net.jarcec.AvroParquet.reproCase(AvroParquet.java:49)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
	at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:51)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:237)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
{code}

I'm attaching a small maven project with all the dependencies to make it easier to reproduce locally.

Trying to isolate the problem further, it seems that the [AvroSchemaConverter|https://git-wip-us.apache.org/repos/asf?p=parquet-mr.git;a=blob;f=parquet-avro/src/main/java/org/apache/parquet/avro/AvroSchemaConverter.java;h=70b6525f6059889889dd5fc321322d045613a8cd;hb=refs/heads/master#l111] converts the Avro schema to just {{required binary value (UTF8);}} (e.g. primitive type). But then the writer will go based on the Avro schema (which is a union) and [tries to call asGroupType() on the primite type|https://git-wip-us.apache.org/repos/asf?p=parquet-mr.git;a=blob;f=parquet-avro/src/main/java/org/apache/parquet/avro/AvroWriteSupport.java;h=460565bb01d27c46d342e635860a81cbf45f7b09;hb=refs/heads/master#l357].



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