[jira] [Commented] (ARROW-14104) Reading Lists of Timestamps from parquet files in Arrow 5.0.0 fails to preserve the TimeZone - unlike in Arrow 4.0.0

["Weston Pace (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-14104?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17419375#comment-17419375 ] 

Weston Pace commented on ARROW-14104:
-------------------------------------

I wasn't able to reproduce this using the example script.  Could you possibly provide a few more details around how you are creating and then reading the files?  Could you upload a sample file that should have the America/Denver timezone but does not seem to read that way?  That way we can isolate if the issue is reading or writing the file.

I tested both writing with 5.0 and reading with 5.0 and also writing with 4.0 and reading with 5.0.

I did have to modify your script slightly to get it to run which may have affected things.  Here is what I used:

{code:python}
import datetime

import pyarrow as pa
import pyarrow.parquet as pq

column = pa.array([[datetime.datetime(2023, 9, 23, 11)]], pa.list_(pa.timestamp('us', 'America/New_York')))

t = pa.Table.from_arrays([column], names=['TimestampColumn'])
pq.write_table(t, "example.parq")

t2 = pq.read_table("example.parq")
print(t2)
{code}

> Reading Lists of Timestamps from parquet files in Arrow 5.0.0 fails to preserve the TimeZone - unlike in Arrow 4.0.0
> --------------------------------------------------------------------------------------------------------------------
>
>                 Key: ARROW-14104
>                 URL: https://issues.apache.org/jira/browse/ARROW-14104
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: C++, Parquet, Python
>    Affects Versions: 5.0.0
>            Reporter: Sarah Gilmore
>            Priority: Minor
>
> In Arrow 4.0.0 it is possible to round-trip the TimeZone property of List<Timestamp> columns to and from parquet files: 
> {code:java}
> >>> import pyarrow as pa
> >>> import pyarrow.parquet as pq
> >>> column = pa.array([[datetime.datetime(2023, 9, 23, 11)]], pa.list_(pa.timestamp('us', 'America/New_York'));
> >>> t = pa.Table.from_arrays([column], name=['TimestampColumn']);
> >>> pq.write_table(t, "example.parq");
> >>> t2 = pq.read_table("example.parq");
> >>> t2
> pyarrow.Table
> Dates: list<item: timestamp[us, tz=America/Denver]>
>   child 0, item: timestamp[us, tz=America/Denver]
> {code}
> However, if you read the same parquet file in pyarrow 5.0.0, the TimeZone is set to UTC:
> {code:java}
> >>> t3 = pq.read_table("example.parq");
> >>> t3
> pyarrow.Table
> Dates: list<item: timestamp[us, tz=UTC]>
>   child 0, item: timestamp[us, tz=UTC]
>  {code}
>  
> I noticed that the TimeZone is preserved in Arrow 5.0 when reading non-nested timestamp columns. 



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