Schema change results in exception - java.lang.ClassCastException

Following exception was seen with parquet 1.8.1 (and in parquet 1.12.0, when trying to reproduce it).

Exception in thread "main" java.lang.ClassCastException: optional binary phone_number (STRING) is not a group
at com.uber.komondor.shaded.org.apache.parquet.schema.Type.asGroupType(Type.java:250)
at com.uber.komondor.shaded.org.apache.parquet.avro.AvroRecordConverter.newConverter(AvroRecordConverter.java:279)
at com.uber.komondor.shaded.org.apache.parquet.avro.AvroRecordConverter.newConverter(AvroRecordConverter.java:232)
at com.uber.komondor.shaded.org.apache.parquet.avro.AvroRecordConverter.access$100(AvroRecordConverter.java:78)
at org.apache.parquet.avro.AvroRecordConverter$AvroCollectionConverter$ElementConverter.(AvroRecordConverter.java:536)
at org.apache.parquet.avro.AvroRecordConverter$AvroCollectionConverter.(AvroRecordConverter.java:486)
at org.apache.parquet.avro.AvroRecordConverter.newConverter(AvroRecordConverter.java:289)
at org.apache.parquet.avro.AvroRecordConverter.(AvroRecordConverter.java:141)
at org.apache.parquet.avro.AvroRecordConverter.newConverter(AvroRecordConverter.java:279)
at org.apache.parquet.avro.AvroRecordConverter.(AvroRecordConverter.java:141)
at org.apache.parquet.avro.AvroRecordConverter.(AvroRecordConverter.java:95)
at org.apache.parquet.avro.AvroRecordMaterializer.(AvroRecordMaterializer.java:33)
at org.apache.parquet.avro.AvroReadSupport.prepareForRead(AvroReadSupport.java:138)
at org.apache.parquet.hadoop.InternalParquetRecordReader.initialize(InternalParquetRecordReader.java:183)
at org.apache.parquet.hadoop.ParquetReader.initReader(ParquetReader.java:156)
at org.apache.parquet.hadoop.ParquetReader.read(ParquetReader.java:135)
at util.ParquetToAvroSchemaConverter$.convert(ParquetToAvroSchemaConverter.scala:46)
at util.ParquetToAvroSchemaConverter$.main(ParquetToAvroSchemaConverter.scala:20)
at util.ParquetToAvroSchemaConverter.main(ParquetToAvroSchemaConverter.scala)
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.apache.hadoop.util.RunJar.run(RunJar.java:221)
at org.apache.hadoop.util.RunJar.main(RunJar.java:136)

Original exception was triggered by the following schema change.
Schema Before change:
{
"default": null,
"name": "master_cluster",
"type": [
"null",
{
"fields": [
{
"name": "uuid",
"type": "string"
},
{
"name": "namespace",
"type": "string"
},
{
"name": "version",
"type": "long"
}
],
"name": "master_cluster",
"type": "record"
}
]
},

After schema change:
{
"default": null,
"name": "master_cluster",
"type": [
"null",
{
"fields": [
{
"default": null,
"name": "uuid",
"type": [
"null",
"string"
]
},
{
"default": null,
"name": "namespace",
"type": [
"null",
"string"
]
},
{
"default": null,
"name": "version",
"type": [
"null",
"long"
]
}
],
"name": "VORGmaster_cluster",
"type": "record"
}
]
},

We were suspecting PARQUET-1441 could be in play and tried to reproduce the issue on parquet-1.12.0 and seeing the same exception.

During the repro noticed that issue could be with avroSchema conversion (field name was substituted with generic name "array"). While we look into this further, want to get community input on whether this is a known issue and any thoughts on path forward.

19/09/12 22:34:37 DEBUG avro.SchemaCompatibility: Checking compatibility of reader {"type":"record","name":"IDphones_items","fields":[{"name":"phone_number","type":["null","string"],"default":null}]} with writer {"type":"record","name":"array","fields":[{"name":"phone_number","type":["null","string"],"default":null}]}

**Environment**: Hoodie/Parquet/Avro

Parquet-1.8.1

Avro-1.7.6
**Reporter**: [Balajee Nagasubramaniam](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=balajeeUber)
**Assignee**: [Xinli Shang](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=shangx@uber.com) / @shangxinli
#### Externally tracked issue: [https://issues.apache.org/jira/browse/PARQUET-1681](https://issues.apache.org/jira/browse/PARQUET-1681)

_{**Note**: *This issue was originally created as [PARQUET-1656](https://issues.apache.org/jira/browse/PARQUET-1656). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

从 AvroRecordConverter 和 AvroReadSupport 中的堆栈跟踪入口点开始，然后检查报告中的转换行所在的 util.ParquetToAvroSchemaConverter.scala。比较变更前后的 schema 以及记录的 reader/writer schema，并查看外部跟踪的 PARQUET-1681 issue，以确定当前状态和 definition of done。

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