[GitHub] [arrow] jhorstmann commented on pull request #8161: ARROW-9961: [Rust][DataFusion] Make to_timestamp function parses timestamp without timezone offset as local

[GitBox <gi...@apache.org>]

jhorstmann commented on pull request #8161:
URL: https://github.com/apache/arrow/pull/8161#issuecomment-691464193


   I guess one choice has to be made, whether to default to local timezone or utc, and it's always possible to set the local timezone to utc to avoid these issues. My only concern is that this could cause tests to fail if they use local timestamps and are then run on machines with different time zones. This can probably only be solved with careful review, and by hopefully having the ci run with different time zones than your local machines.
   
   One (not directly related) issue I noticed while trying this out, is that the local patterns seem to require the millisecond part, while for utc timestamps with "Z" they are optional:
   
   ```
   > select to_timestamp('2020-09-12T10:30:00') from test limit 1;
   ArrowError(ExternalError(General("Error parsing \'2020-09-12T10:30:00\' as timestamp")))
   
   > select to_timestamp('2020-09-12T10:30:00Z') from test limit 1;
   +-------------------------------------------+
   | totimestamp(Utf8("2020-09-12T10:30:00Z")) |
   +-------------------------------------------+
   | 1599906600000000000                       |
   +-------------------------------------------+
   ```


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