eddietejeda opened a new issue, #24765:
URL: https://github.com/apache/datafusion/issues/24765
### Is your feature request related to a problem or challenge?
`octet_length` only accepts string types. When we use a binary column, the
plan fails:
```text
Function 'octet_length' requires String, but received Binary (DataType:
BinaryView)
```
A workaround for `SUM(octet_length(col))` over binary is:
```sql
SUM(length(encode(col, 'hex')) / 2)
```
But this materializes 2x the column's bytes just to count it.
### Describe the solution you'd like
Extend `octet_length` to natively accept `Binary`, `LargeBinary`, and
`BinaryView`, returning the byte length.
- SQL:1999 defines `OCTET_LENGTH` for string values, including binary
strings.
- PostgreSQL, DuckDB, Spark, MySQL, and SQLite accept binary values.
- `utf8_to_int_type` already maps `Binary -> Int32`, `LargeBinary -> Int64`,
and `BinaryView -> Int32`.
We've implemented the solution internally and happy to submit PR.
`datafusion/functions/src/string/octet_length.rs`
Before:
```rust
impl OctetLengthFunc {
pub fn new() -> Self {
Self {
signature: Signature::coercible(
vec![
Coercion::new_exact(TypeSignatureClass::Native(logical_string()))
.with_encoding_preservation(EncodingPreservation::dictionary()),
],
Volatility::Immutable,
),
}
}
}
```
After: the two-branch string|binary select that `md5` uses:
```rust
impl OctetLengthFunc {
pub fn new() -> Self {
Self {
signature: Signature::one_of(
vec![
TypeSignature::Coercible(vec![
Coercion::new_exact(TypeSignatureClass::Native(logical_string()))
.with_encoding_preservation(
EncodingPreservation::dictionary(),
),
]),
TypeSignature::Coercible(vec![
Coercion::new_exact(TypeSignatureClass::Native(logical_binary()))
.with_encoding_preservation(
EncodingPreservation::dictionary(),
),
]),
],
Volatility::Immutable,
),
}
}
}
```
### Describe alternatives you've considered
```rust
length(encode(col, 'hex')) / 2 // works but doubles the data to count it
```
### Additional context
`bit_length` has the same gap and could be part in the same PR.
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