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https://issues.apache.org/jira/browse/ARROW-10514?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Antoine Pitrou resolved ARROW-10514.
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Fix Version/s: 4.0.0
Resolution: Fixed
Issue resolved by pull request 9649
[https://github.com/apache/arrow/pull/9649]
> [C++][Parquet] Data inconsistency in parquet-reader output modes
> ----------------------------------------------------------------
>
> Key: ARROW-10514
> URL: https://issues.apache.org/jira/browse/ARROW-10514
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++
> Reporter: Zosimova Zhanna
> Priority: Minor
> Labels: pull-request-available
> Fix For: 4.0.0
>
> Attachments:
> 0001-Make-the-column-name-the-same-for-both-output-format.patch
>
> Time Spent: 1h
> Remaining Estimate: 0h
>
> I tried reading description for Parquet
> [file|https://github.com/ClickHouse/ClickHouse/blob/master/tests/queries/0_stateless/data_parquet/nested_maps.snappy.parquet]
> with nested maps using [parquet-reader
> tool|https://github.com/apache/arrow/blob/master/cpp/tools/parquet/parquet_reader.cc].
>
> This file has the following structure:
> {code:java}
> required group field_id=0 spark_schema {
> optional group field_id=1 a (Map) {
> repeated group field_id=2 key_value {
> required binary field_id=3 key (String);
> optional group field_id=4 value (Map) {
> repeated group field_id=5 key_value {
> required int32 field_id=6 key;
> required boolean field_id=7 value;
> }
> }
> }
> }
> required int32 field_id=8 b;
> required double field_id=9 c;
> } {code}
> When I print it using DebugPrint, I see:
> {code:java}
> $ ./parquet-reader nested_maps.snappy.parquet --only-metadata
> <some text is omitted for the sake of readability>
> Column 0: a.key_value.key (BYTE_ARRAY/UTF8)
> Column 1: a.key_value.value.key_value.key (INT32)
> Column 2: a.key_value.value.key_value.value (BOOLEAN)
> Column 3: b (INT32)
> Column 4: c (DOUBLE)
> </some text is omitted for the sake of readability>{code}
> When I pring it using JSONPrint, I see:
> {code:java}
> $ ./parquet-reader nested_maps.snappy.parquet --json
> <some text is omitted for the sake of readability>
> "Columns": [
> { "Id": "0", "Name": "key", "PhysicalType": "BYTE_ARRAY", "ConvertedType":
> "UTF8", "LogicalType": {"Type": "String"} },
> { "Id": "1", "Name": "key", "PhysicalType": "INT32", "ConvertedType":
> "NONE", "LogicalType": {"Type": "None"} },
> { "Id": "2", "Name": "value", "PhysicalType": "BOOLEAN", "ConvertedType":
> "NONE", "LogicalType": {"Type": "None"} },
> { "Id": "3", "Name": "b", "PhysicalType": "INT32", "ConvertedType": "NONE",
> "LogicalType": {"Type": "None"} },
> { "Id": "4", "Name": "c", "PhysicalType": "DOUBLE", "ConvertedType":
> "NONE", "LogicalType": {"Type": "None"} }
> ]
> </some text is omitted for the sake of readability>{code}
> Column 0 and Column 1 has the same Name in JSON output. That's very
> confusing. It would be more correct to output the full path of the column
> (key -> a.key_value.key).
>
> This issue can be corrected by changing a single line:
> [https://github.com/apache/arrow/blob/master/cpp/src/parquet/printer.cc#L218]
>
> The proposed patch in the attachment
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