rohitrastogi commented on code in PR #399:
URL: https://github.com/apache/datafusion-comet/pull/399#discussion_r1596117835
##########
core/src/execution/datafusion/expressions/cast.rs:
##########
@@ -232,6 +232,240 @@ macro_rules! cast_int_to_int_macro {
}};
}
+// When Spark casts to Byte/Short Types, it does not cast directly to
Byte/Short.
+// It casts to Int first and then to Byte/Short. Because of potential
overflows in the Int cast,
+// this can cause unexpected Short/Byte cast results. Replicate this behavior.
+macro_rules! cast_float_to_int16_down {
+ (
+ $array:expr,
+ $eval_mode:expr,
+ $src_array_type:ty,
+ $dest_array_type:ty,
+ $rust_src_type:ty,
+ $rust_dest_type:ty,
+ $src_type_str:expr,
+ $dest_type_str:expr,
+ $format_str:expr
+ ) => {{
+ let cast_array = $array
+ .as_any()
+ .downcast_ref::<$src_array_type>()
+ .expect(concat!("Expected a ", stringify!($src_array_type)));
+
+ let output_array = match $eval_mode {
+ EvalMode::Ansi => cast_array
+ .iter()
+ .map(|value| match value {
+ Some(value) => {
+ let is_overflow = value.is_nan() || value.abs() as i32
== std::i32::MAX;
Review Comment:
@andygrove This condition is actually incorrect.
Should be something like:
```
let is_overflow = value.is_nan() || (value as f64).floor() > (std::i32::MAX
as f64) || (value as f64).ceil() < (std::i32::MIN as f64);
```
This is what Scala does in FloatExactNumeric.
Working on a fix with some improved tests. It looks like there are some
tedious edge cases on how Java/Scala format the error strings depending on how
large the float is.
Rust and Scala format the same float as decimals with different precisions
when printing, which makes it challenging to get the same error output as Spark
in ANSI mode. Not sure how to address that - we may need to relax the exact
string match criteria for float -> int conversions and warn users that though
the error checking logic from vanilla Spark/Comet are the same, the error
messages are different.
For example:
For INT_MAX, Rust prints 2.1474836E9, whereas Java prints 2.14748365E9. Both
printouts correspond to the same float 2147483648.
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