friendlymatthew commented on code in PR #15361:
URL: https://github.com/apache/datafusion/pull/15361#discussion_r2015455219
##########
datafusion/functions/src/datetime/to_char.rs:
##########
@@ -277,7 +282,25 @@ fn _to_char_array(args: &[ColumnarValue]) ->
Result<ColumnarValue> {
let result = formatter.value(idx).try_to_string();
match result {
Ok(value) => results.push(Some(value)),
- Err(e) => return exec_err!("{}", e),
+ Err(e) => {
+ if data_type == &Date32 {
Review Comment:
I took another look and reached a different conclusion from above. I fear
[1e57ed1](https://github.com/apache/datafusion/pull/15361/commits/1e57ed10f03b352fd2588fb8adf011e2f15766bd)
is performing way too many casts in the retry logic, and it is better to
implicitly treat `Date32` as timestamps ahead of time.
`to_char` invokes either `to_char_scalar` or `to_char_array` based on the
number of formats provided in the arguments (i.e. N dates with 1 format string
or N dates with N format strings). If any of the dates err when formatting,
we'd cast all N dates as `Date64`s and redo the body of work.
While this would be fine with `to_char_scalar` because a format string with
a time-specifier would err for any `Date32`, so at worst it'd err, cast, and
retry after the first format attempt. But in `to_char_array` where we're
iterating through N format strings, at worst we'd need to recast the _entire_
`Date32` array N times*.
Since we can't avoid the `Date32` to `Date64` cast to support this feature,
it's much simpler to check ahead of time and cast the input `Date32` array into
a `Date64` array. Plus, all date-specifiers are valid in timestamp formatting,
so existing features work as expected.
I pushed
[12e2314](https://github.com/apache/datafusion/pull/15361/commits/12e2314edcaa6ae0b7378a1986560b7a123bf3f2)
as a proof of concept. But I'd be happy to rework it as you see fit.
<br>
_*The entire `Date32` array because for every format string, we create a new
`ArrayFormatter` by supplying the entire array and specifying the index for the
formatter to format:_
https://github.com/apache/datafusion/blob/fdb4e848b65c001dd3f65b477296e07cbe8e0b07/datafusion/functions/src/datetime/to_char.rs#L274-L277
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