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https://issues.apache.org/jira/browse/ARROW-17459?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17599111#comment-17599111
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Micah Kornfield commented on ARROW-17459:
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Its probably a case of different batch sizes.
suppose you have 100 rows that take have 3GB of string evenly distributed. If
you try to read all 100 rows it will overflow and create a ChunkedArray. If
you read 50 rows at a time it would be an issue because chunking wouldn't be
necessary.
> [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
> Assignee: 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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