Make from_unixtime aware of execution timezone #12892
Description
Is your feature request related to a problem or challenge?
No response
Describe the solution you'd like
Applies an offset to the unixtime after the cast.
Describe alternatives you've considered
No response
Additional context
Datafusion's from_unixtime is not aware of timezone. The following code block demonstrates the interaction between me and datafusion-cli.
> set datafusion.execution.time_zone = '+08:00';
0 row(s) fetched.
Elapsed 0.000 seconds.
> select to_unixtime('2024-09-01 10:00:00+08:00');
+------------------------------------------------+
| to_unixtime(Utf8("2024-09-01 10:00:00+08:00")) |
+------------------------------------------------+
| 1725156000 |
+------------------------------------------------+
1 row(s) fetched.
Elapsed 0.001 seconds.
> select from_unixtime(1725156000);
+----------------------------------+
| from_unixtime(Int64(1725156000)) |
+----------------------------------+
| 2024-09-01T02:00:00 |
+----------------------------------+
1 row(s) fetched.
Elapsed 0.001 seconds.Specifically, when converting a date to unixtime with the to_unixtime function, we can provide a timezone and the cast result could reveal the timezone. However, when converting the unixtime back to a date, Datafusion is not aware of timezone. Yes, the cast result is correct, but the timezone info is discarded and only a date with timezone UTC+0 is returned.
I wonder if we can make the from_unixtime function aware of timezone. For example, by setting the execution timezone through the datafusion.execution.time_zone configuration, we can apply an offset to the cast result so the timezone info could be revealed.