[jira] [Comment Edited] (PARQUET-1681) Avro's isElementType() change breaks the reading of some parquet(1.8.1) files

["Xinli Shang (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PARQUET-1681?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16969483#comment-16969483 ] 

Xinli Shang edited comment on PARQUET-1681 at 11/7/19 6:28 PM:
---------------------------------------------------------------

Hi [~rdblue], do you still remember or document it somewhere what are the several problems that  PARQUET-651 solved? Is SPARK-16344 the only problem sovled? I am evaluating should we roll back PARQUET-651  or roll forward. 


was (Author: shangx@uber.com):
Hi [~rdblue], do you still remember or document it somewhere what are the several problems that  PARQUET-651 solved? I am evaluating should we roll back PARQUET-651  or roll forward. 

> Avro's isElementType() change breaks the reading of some parquet(1.8.1) files
> -----------------------------------------------------------------------------
>
>                 Key: PARQUET-1681
>                 URL: https://issues.apache.org/jira/browse/PARQUET-1681
>             Project: Parquet
>          Issue Type: Improvement
>          Components: parquet-avro
>    Affects Versions: 1.10.0, 1.9.1, 1.11.0
>            Reporter: Xinli Shang
>            Assignee: Xinli Shang
>            Priority: Critical
>
> When using the Avro schema below to write a parquet(1.8.1) file and then read back by using parquet 1.10.1 without passing any schema, the reading throws an exception "XXX is not a group" . Reading through parquet 1.8.1 is fine. 
>            {
>               "name": "phones",
>               "type": [
>                 "null",
>                 {
>                   "type": "array",
>                   "items": {
>                     "type": "record",
>                     "name": "phones_items",
>                     "fields": [
>                       
> {                         "name": "phone_number",                         "type": [                           "null",                           "string"                         ],                         "default": null                       }
>                     ]
>                   }
>                 }
>               ],
>               "default": null
>             }
> The code to read is as below 
>      val reader = AvroParquetReader._builder_[SomeRecordType](parquetPath).withConf(*new*   Configuration).build()
>     reader.read()
> PARQUET-651 changed the method isElementType() by relying on Avro's checkReaderWriterCompatibility() to check the compatibility. However, checkReaderWriterCompatibility() consider the ParquetSchema and the AvroSchema(converted from File schema) as not compatible(the name in avro schema is ‘phones_items’, but the name is ‘array’ in Parquet schema, hence not compatible) . Hence return false and caused the “phone_number” field in the above schema to be considered as group type which is not true. Then the exception throws as .asGroupType(). 
> I didn’t try writing via parquet 1.10.1 would reproduce the same problem or not. But it could because the translation of Avro schema to Parquet schema is not changed(didn’t verify yet). 
>  I hesitate to revert PARQUET-651 because it solved several problems. I would like to hear the community's thoughts on it. 



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