dwsmith1983 opened a new pull request, #5874:
URL: https://github.com/apache/datafusion-comet/pull/5874

   ## Which issue does this PR close?
   
   Closes #2348.
   
   ## Rationale for this change
   
   `length(binary)` currently falls back to Spark because Comet registered 
DataFusion's `character_length`, which accepts string types only. 
`datafusion-spark` now ships a Spark-compatible `length` that returns the byte 
count for binary and the character count for strings, so the fallback can go.
   
   ## What changes are included in this PR?
   
   - Register `SparkLengthFunc` in the native session under `length`, 
`char_length`, `character_length` and `len`, replacing `character_length`. The 
result is `Int32` for every input width, matching Spark.
   - Drop the `BinaryType` fallback from `CometLength`.
   - A Rust roundtrip test through the Parquet schema adapter shows 
dictionary-typed string and binary columns are cast to `Utf8`/`Binary` before 
any expression sees them, so the replaced function's dictionary handling is not 
needed downstream. A Scala test reads a small Arrow-written Parquet file whose 
embedded schema declares dictionary-typed columns and checks `length` runs 
natively on it.
   - Refresh the audit note in the string function audit doc and the stale 
notes in the `bit_length`/`octet_length` fixtures.
   
   ## How are these changes tested?
   
   - `length.sql` gains a binary table and queries covering multi-byte text, 
bytes that are not valid UTF-8, embedded NUL bytes, empty, NULL and all-NULL 
columns, binary reached through a struct field, an array element, a map value, 
`unhex`, `substring` and `CAST(string AS BINARY)`, the `Int32` result in 
arithmetic, a filter, a `GROUP BY` aggregate and after a native shuffle, and 
the `char_length`/`character_length` aliases. Every block asserts a fully 
native plan.
   - `CometStringExpressionSuite` runs `length` on 1000 binary rows with and 
without dictionary encoding, and on the dictionary-typed file described above.
   - A Rust test asserts `length` resolves to the Spark function returning 
`Int32` for `Utf8`, `LargeUtf8`, `Utf8View`, `Binary`, `LargeBinary` and 
`BinaryView` with no cast inserted.
   - Verified locally on Spark 3.5 and 4.0: `CometSqlFileTestSuite length`, 
`CometStringExpressionSuite`, `cargo test`, `cargo clippy -D warnings`, 
spotless.
   


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