alamb commented on a change in pull request #10005:
URL: https://github.com/apache/arrow/pull/10005#discussion_r612805624
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File path: rust/datafusion/src/sql/planner.rs
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@@ -1498,6 +1498,7 @@ pub fn convert_data_type(sql: &SQLDataType) ->
Result<DataType> {
SQLDataType::Double => Ok(DataType::Float64),
SQLDataType::Char(_) | SQLDataType::Varchar(_) => Ok(DataType::Utf8),
SQLDataType::Timestamp => Ok(DataType::Timestamp(TimeUnit::Nanosecond,
None)),
+ SQLDataType::Time => Ok(DataType::Timestamp(TimeUnit::Millisecond,
None)),
Review comment:
@velvia
> Is this only for time of the day?
That is my understanding
> What I really need is a convenient way to cast things
toTimestamp(Milliseconds, None) .. what do you recommend?
I recommend adding a new function that takes a string parameter that is
interpreted at an Arrow `DataType` and calls the appropriate underlying arrow
cast function. This way we can specify the arrow type directly without having
to worry about an incomplete mapping of SQL type <--> Arrow type
Perhaps something like
```
select arrow_cast(my_col, 'Timestamp(Milliseconds, None)'
```
I haven't thought carefully about how we would parse the strings back to
`DateTime` but I think we might be able to press some existing serde code into
use, perhaps.
What do you think @jorgecarleitao , @seddonm1 , @returnString ?
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