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https://issues.apache.org/jira/browse/PARQUET-2069?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17536902#comment-17536902
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Timothy Miller commented on PARQUET-2069:
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Yup. If I force prepareForRead() to ignore the avro schema in the metadata,
then the modified.parquet file parses just fine, even without the code in the
PR.
What do y'all say to us ditching entirely the attempt to salvage the avro
schema from the metadata? That would make a bunch of reported parsing problems
go away. It seems like the file writer is modifying the file schema in a way
that becomes incompatible with the avro schema it attempts to save. If we want
to go with the new format, we should stop trying to use the avro schema.
> Parquet file containing arrays, written by Parquet-MR, cannot be read again
> by Parquet-MR
> -----------------------------------------------------------------------------------------
>
> Key: PARQUET-2069
> URL: https://issues.apache.org/jira/browse/PARQUET-2069
> Project: Parquet
> Issue Type: Bug
> Components: parquet-avro
> Affects Versions: 1.12.0
> Environment: Windows 10
> Reporter: Devon Kozenieski
> Priority: Blocker
> Attachments: modified.parquet, original.parquet, parquet-diff.png
>
>
> In the attached files, there is one original file, and one written modified
> file that results after reading the original file and writing it back with
> Parquet-MR, with a few values modified. The schema should not be modified,
> since the schema of the input file is used as the schema to write the output
> file. However, the output file has a slightly modified schema that then
> cannot be read back the same way again with Parquet-MR, resulting in the
> exception message: java.lang.ClassCastException: optional binary element
> (STRING) is not a group
> My guess is that the issue lies in the Avro schema conversion.
> The Parquet files attached have some arrays and some nested fields.
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