[jira] [Commented] (ARROW-12117) [C++][Parquet] Root message of parquet may contain repetition

["Antoine Pitrou (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-12117?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17313270#comment-17313270 ] 

Antoine Pitrou commented on ARROW-12117:
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While the spec seems to say so, a quick look at some of the files in [https://github.com/apache/parquet-testing/tree/master/data] shows that the root node always has a defined repetition of REQUIRED. Am I reading it wrong?

> [C++][Parquet] Root message of parquet may contain repetition
> -------------------------------------------------------------
>
>                 Key: ARROW-12117
>                 URL: https://issues.apache.org/jira/browse/ARROW-12117
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: C++
>            Reporter: Jorge Leitão
>            Priority: Minor
>              Labels: parquet
>
> According to the parquet format, [the root message does not contain a repetition|https://github.com/apache/parquet-format/blob/master/src/main/thrift/parquet.thrift#L363]. However, it seems that cpp implementation is writing one.
> I noticed this while going through the Rust parquet reader, that has some comments in this direction: E.g.
> [https://github.com/apache/arrow/blob/5be69789eeac0f2c357cfcd0d329c518848adebc/rust/parquet/src/schema/types.rs#L1091]
> and
> [https://github.com/apache/arrow/blob/5be69789eeac0f2c357cfcd0d329c518848adebc/rust/parquet/src/schema/types.rs#L2059]
>  



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