alamb commented on issue #686:
URL:
https://github.com/apache/arrow-datafusion/issues/686#issuecomment-884429679
Let's make this concrete. Here is a proposal of what I think makes sense
(and I think the consistent with @velvia's suggestion for a second argument).
The second argument simply serves to define the output type; Note to really
make this useful we would also have to provide some way within Arrow and
DataFusion to cast back and forth between different timestamps, doing the
offset conversions appropriately
| Example | Output Arrow Type
| Value
| ------------------------------------------ |
------------------------------------ |
------------------------------------------------------
| to_timestamp('2021-07-20') | `Timestamp(Nanoseconds, None)`
| nanos since unix epic until 2021-07-20 local time
| to_timestamp('2021-07-20+00:00') | `Timestamp(Nanoseconds, None)`
| nanos since unix epic until 2021-07-20 UTC
| to_timestamp('2021-07-20+01:00') | `Timestamp(Nanoseconds, None)`
| nanos since unix epic until 2021-07-20 UTC+1
| to_timestamp('2021-07-20', 'UTC') | `Timestamp(Nanoseconds, Utc)`
| nanos since unix epic until 2021-07-20 local time
| to_timestamp('2021-07-20+00:00', 'UTC') | `Timestamp(Nanoseconds, Utc)`
| nanos since unix epic until 2021-07-20 UTC,
| to_timestamp('2021-07-20+01:00', 'UTC') | `Timestamp(Nanoseconds, Utc)`
| nanos since unix epic until 2021-07-20 UTC __NOTE only this timestamps
value needs to be shifted to some other value to be relative to UTC__
I think @adamhooper 's point that "someone might get confused about what
timezone the second argument is referring to" at
https://github.com/apache/arrow-datafusion/issues/686#issuecomment-875815801 is
legitmate, but one we can handle with appropriate documentation.
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