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https://issues.apache.org/jira/browse/ARROW-4359?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16833585#comment-16833585
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Joris Van den Bossche commented on ARROW-4359:
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The arrow field metadata could in principle map to parquet's
{{ColumnChunkMetaData->key_value_metadata}}, but I don't think this is
implemented.
The {{key_value_metadata}} on the full schema _is_ implemented, and this
roundtrips to parquet.
> [Python] Column metadata is not saved or loaded in parquet
> ----------------------------------------------------------
>
> Key: ARROW-4359
> URL: https://issues.apache.org/jira/browse/ARROW-4359
> Project: Apache Arrow
> Issue Type: Bug
> Components: Python
> Reporter: Seb Fru
> Priority: Major
> Labels: parquet
>
> Hi all,
> a while ago I posted this issue: ARROW-3866
> While working with Pyarrow I encountered another potential bug related to
> column metadata: If I create a table containing columns with metadata
> everything is fine. But after I save the table to parquet and load it back as
> a table using pq.read_table, the column metadata is gone.
>
> As of now I can not say yet whether the metadata is not saved correctly or
> not loaded correctly, as I have no idea how to verify it. Unfortunately I
> also don't have the time try a lot, but I wanted to let you know anyway.
>
> {code}
> field0 = pa.field('field1', pa.int64(), metadata=dict(a="A", b="B"))
> field1 = pa.field('field2', pa.int64(), nullable=False)
> columns = [
> pa.column(field0, pa.array([1, 2])),
> pa.column(field1, pa.array([3, 4]))
> ]
> table = pa.Table.from_arrays(columns)
> pq.write_table(tab, path)
> tab2 = pq.read_table(path)
> tab2.column(0).field.metadata
> {code}
>
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