himadripal opened a new issue, #7355:
URL: https://github.com/apache/arrow-rs/issues/7355
- Existing string to decimal cast uses parse_string_to_decimal_native
- parse_string_to_decimal_native does not have support for e-notation
- parse_string_to_decimal_native does rounding at scale, not truncate
- parse_decimal an existing method has e-notation support and use elsewhere
like arrow-csv, arrow-json.
- parse_decimal tests with scale 0, fails as shown below
```rust
assert_eq!(
parse_decimal::<Decimal128Type>("123.45", 38, 0)?,
123_i128
);
assertion `left == right` failed
Left: 12345
Right: 123
```
- existing test using parse_decimal native works
```rust
assert_eq!(
parse_string_to_decimal_native::<Decimal128Type>("123.45", 0)?,
123_i128
);
```
- pars_decimal truncates as defualt behavior,
parse_string_to_decimal_native does rounding, hence read from json, or csv of a
decimal has truncated value but result of a cast operation has rounded value.
```rust
assert_eq!(
parse_decimal::<Decimal128Type>("123.4567891", 38, 5)?,
12345679_i128
);
assertion `left == right` failed
left: 12345678
right: 12345679
```
vs
```
assert_eq!(
parse_string_to_decimal_native::<Decimal128Type>("123.4567891",
5)?,
12345679_i128
);
works fine..
```
This issue was raised as part of investigation to fix this [datafusion
issue] (https://github.com/apache/datafusion/issues/10315)
if parse_decimal add rounding logic and fix the issue with scale=0, parse
decimal can be used for string to decimal cast, thereby getting the scientific
notation along with it.
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