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https://issues.apache.org/jira/browse/ARROW-17459?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17584808#comment-17584808
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Arthur Passos commented on ARROW-17459:
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I am also trying to write test to cover this case, but failing to do so. For
some reason, the files I generate with the very same schema and size don't get
chunked while reading it. The original file was provided by a customer and it's
confidential data, so it can't be used.
All the files I generated contain the above mentioned schema. The differences
are in the data length. Some had maps of 50~300 elements with keys of random
strings of 20~50 characters and values of random strings of 50~5000 characters.
I also tried a low cardinality example and a large string example (2^30
characters).
I'd be very thankful if someone could give me some tips on how to generate a
file that will trigger the exception.
> [C++] Support nested data conversions for chunked array
> -------------------------------------------------------
>
> Key: ARROW-17459
> URL: https://issues.apache.org/jira/browse/ARROW-17459
> Project: Apache Arrow
> Issue Type: New Feature
> Components: C++
> Reporter: Arthur Passos
> Priority: Blocker
>
> `FileReaderImpl::ReadRowGroup` fails with "Nested data conversions not
> implemented for chunked array outputs". It fails on
> [ChunksToSingle]([https://github.com/apache/arrow/blob/7f6b074b84b1ca519b7c5fc7da318e8d47d44278/cpp/src/parquet/arrow/reader.cc#L95])
> Data schema is:
> {code:java}
> optional group fields_map (MAP) = 217 {
> repeated group key_value {
> required binary key (STRING) = 218;
> optional binary value (STRING) = 219;
> }
> }
> fields_map.key_value.value-> Size In Bytes: 13243589 Size In Ratio: 0.20541047
> fields_map.key_value.key-> Size In Bytes: 3008860 Size In Ratio: 0.046667963
> {code}
> Is there a way to work around this issue in the cpp lib?
> In any case, I am willing to implement this, but I need some guidance. I am
> very new to parquet (as in started reading about it yesterday).
>
> Probably related to: https://issues.apache.org/jira/browse/ARROW-10958
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