pitrou commented on code in PR #41187: URL: https://github.com/apache/arrow/pull/41187#discussion_r1598410714
########## docs/source/cpp/parquet.rst: ########## @@ -542,13 +542,28 @@ As an example, when serializing an Arrow LargeList to Parquet: :func:`ArrowWriterProperties::store_schema` was enabled when writing the file; otherwise, it is decoded as an Arrow List. + Serialization details """"""""""""""""""""" The Arrow schema is serialized as a :ref:`Arrow IPC <format-ipc>` schema message, then base64-encoded and stored under the ``ARROW:schema`` metadata key in the Parquet file metadata. +Field Id +-------- + +The Parquet format supports an optional integer "field id" which can be assigned +to a field. This is used for example in the +`Apache Iceberg specification <https://github.com/apache/iceberg/blob/main/format/spec.md#column-projection>`__. + +On the writer side, If ``PARQUET:field_id`` is present as a metadata key on an Arrow field, +and the corresponding value is a non-negative integer, then it will be used as +the "field id" in the Parquet file. + +On the reader side, Arrow will convert these "field id"s to a metadata key named +``PARQUET:field_id`` on the corresponding Arrow field. + Limitations Review Comment: Can you take a look at the rendered output (you can preview on GitHub UI) and make sure the heading are structurally consistent? Especially, the "limitations" heading below relates to supported data types. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@arrow.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
