Truc Lam Nguyen created ARROW-11497: ---------------------------------------
Summary: [Python] pyarrow parquet writer for list does not conform with Apache Parquet sepecification Key: ARROW-11497 URL: https://issues.apache.org/jira/browse/ARROW-11497 Project: Apache Arrow Issue Type: Bug Components: Python Affects Versions: 3.0.0 Reporter: Truc Lam Nguyen Attachments: parquet-tools-meta.log Sorry if I don't know this feature is done deliberately, but it looks like the parquet writer for list data type does not confirm to Apache Parquet list logical type specification, According to this page: [https://github.com/apache/parquet-format/blob/master/LogicalTypes.md#lists,] list type contains 3 level where the middle level, named {{list}}, must be a repeated group with a single field named _{{element}}_ However, in the parquet file from pyarrow writer, that single field is named _item_ instead, Please find below the example python code that produce a parquet file (I use pandas version 1.2.1 and pyarrow version 3.0.0) {code:java} import pandas as pd df = pd.DataFrame(data=[ {'studio': 'blizzard', 'games': [{'name': 'diablo', 'version': '3'}, {'name': 'star craft', 'version': '2'}]}, {'studio': 'ea', 'games': [{'name': 'fifa', 'version': '21'}]}, ]) df.to_parquet('/tmp/test.parquet', engine='pyarrow') {code} Then I use parquet-tools from [https://formulae.brew.sh/formula/parquet-tools] to check the metadata of parquet file via this command parquet-tools meta /tmp/test.parquet The full meta is included in attached, here is only an extraction of list type column games: OPTIONAL F:1 .list: REPEATED F:1 ..item: OPTIONAL F:2 ...name: OPTIONAL BINARY L:STRING R:1 D:4 ...version: OPTIONAL BINARY L:STRING R:1 D:4 as can be seen, under list, it is single field named _item_ I think this should be made to be name _element_ to conform with Apache Parquet specification. -- This message was sent by Atlassian Jira (v8.3.4#803005)