Function hash_field_bytes

nodedb-query/src/msgpack_scan/compare.rs:19–28

Hash the raw bytes of a MessagePack value at `range` within `buf`. Uses a fast non-cryptographic hash suitable for hash joins and GROUP BY. For canonical-encoded documents (integers in smallest form, sorted keys), semantically equal values produce identical byte sequences and thus identical hashes.

(buf: &[u8], range: (usize, usize))

/// semantically equal values produce identical byte sequences and thus
/// identical hashes.
pub fn hash_field_bytes(buf: &[u8], range: (usize, usize)) -> u64 {
    let slice = match buf.get(range.0..range.1) {
        Some(s) => s,
        None => return 0,
    };
    let hasher_builder = std::collections::hash_map::RandomState::new();
    let mut hasher = hasher_builder.build_hasher();
    hasher.write(slice);
    hasher.finish()
}

/// Hash the raw bytes using a provided `RandomState` for consistent hashing
/// within a single query (all docs hashed with the same seed).