docs/source/contributor-guide/expression-audits/hash_funcs.md

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# hash_funcs Expression Audits

> Audit notes for expressions in this category that have been audited. Absence of an entry means the expression has not been audited yet, not that it is unsupported. See the user guide [Spark Expression Support] for current support status.

## crc32

- Spark 3.4.3 (audited 2026-05-27): identical to 3.5.8.
- Spark 3.5.8 (audited 2026-05-27): baseline. `Crc32(child) extends UnaryExpression`; `inputTypes = Seq(BinaryType) -> LongType`. Wired as `CometScalarFunction("crc32")`.
- Spark 4.0.1 (audited 2026-05-27): semantics unchanged; `NullIntolerant` trait replaced by `nullIntolerant: Boolean` override.
- Spark 4.1.1 (audited 2026-05-27): identical to 4.0.1.

## hash

- Spark 3.4.3 (audited 2026-05-27): identical to 3.5.8.
- Spark 3.5.8 (audited 2026-05-27): baseline. `Murmur3Hash(children, seed) extends HashExpression[Int]`; produces a Murmur3 hash with a configurable Int seed and `IntegerType` result. Comet routes via `CometMurmur3Hash` to the native `murmur3_hash` UDF.
- Spark 4.0.1 (audited 2026-05-27): semantics unchanged; some inner helper refactors only.
- Spark 4.1.1 (audited 2026-05-27): identical to 4.0.1.
- Known limitation: `DecimalType` children with precision > 18 fall back because Spark hashes them through Java `BigDecimal`; `TimeType` (Spark 4.0+) is also unsupported. The same limitations apply to `xxhash64`, `sha1`, `sha2` through the shared `HashUtils`.

## md5

- Spark 3.4.3 (audited 2026-05-27): identical to 3.5.8.
- Spark 3.5.8 (audited 2026-05-27): baseline. `Md5(child) extends UnaryExpression`; `inputTypes = Seq(BinaryType) -> StringType`. Wired as `CometScalarFunction("md5")`.
- Spark 4.0.1 (audited 2026-05-27): semantics unchanged; trait set gains `DefaultStringProducingExpression` and the `nullIntolerant: Boolean` refactor.
- Spark 4.1.1 (audited 2026-05-27): identical to 4.0.1.

## sha

- Spark 3.4.3 (audited 2026-05-27): registry alias of `Sha1`. Same support as `sha1`.
- Spark 3.5.8 (audited 2026-05-27): identical to 3.4.3.
- Spark 4.0.1 (audited 2026-05-27): identical to 3.4.3.
- Spark 4.1.1 (audited 2026-05-27): identical to 3.4.3.

## sha1

- Spark 3.4.3 (audited 2026-05-27): identical to 3.5.8.
- Spark 3.5.8 (audited 2026-05-27): baseline. `Sha1(child) extends UnaryExpression with NullIntolerant`; `inputTypes = Seq(BinaryType) -> StringType`. Comet routes via `CometSha1` to the native `sha1` UDF.
- Spark 4.0.1 (audited 2026-05-27): trait set gains `DefaultStringProducingExpression` and `NullIntolerant` is replaced by `nullIntolerant: Boolean`. Runtime unchanged.
- Spark 4.1.1 (audited 2026-05-27): identical to 4.0.1.

## sha2

- Spark 3.4.3 (audited 2026-05-27): identical to 3.5.8.
- Spark 3.5.8 (audited 2026-05-27): baseline. `Sha2(left, right) extends BinaryExpression`; `inputTypes = Seq(BinaryType, IntegerType) -> StringType`. The `numBits` argument selects SHA-224/256/384/512 (0 is treated as 256); other values return NULL. Comet routes via `CometSha2` to the native `sha2` UDF; non-foldable `numBits` falls back to Spark.
- Spark 4.0.1 (audited 2026-05-27): trait set gains `DefaultStringProducingExpression` and the `nullIntolerant: Boolean` refactor. Runtime unchanged.
- Spark 4.1.1 (audited 2026-05-27): identical to 4.0.1.

## xxhash64

- Spark 3.4.3 (audited 2026-05-27): identical to 3.5.8.
- Spark 3.5.8 (audited 2026-05-27): baseline. `XxHash64(children, seed) extends HashExpression[Long]`; produces an xxHash64 hash with a configurable Long seed and `LongType` result. Comet routes via `CometXxHash64` to the native `xxhash64` UDF.
- Spark 4.0.1 (audited 2026-05-27): semantics unchanged.
- Spark 4.1.1 (audited 2026-05-27): identical to 4.0.1.

[Spark Expression Support]: ../../user-guide/latest/expressions.md