Function hash_join_key

nodedb/src/data/executor/handlers/join/hash.rs:14–33

Hash a join key from raw msgpack bytes — zero String allocation. For single-field keys: hashes the raw value bytes directly. For composite keys: hashes each field's raw bytes sequentially. Returns `(hash, key_ranges)` — the ranges are kept for collision resolution via memcmp.

(
    doc: &[u8],
    keys: &[&str],
    state: &std::collections::hash_map::RandomState,
)

/// For composite keys: hashes each field's raw bytes sequentially.
/// Returns `(hash, key_ranges)` — the ranges are kept for collision resolution via memcmp.
pub(super) fn hash_join_key(
    doc: &[u8],
    keys: &[&str],
    state: &std::collections::hash_map::RandomState,
) -> (u64, Vec<(usize, usize)>) {
    use std::hash::{BuildHasher, Hasher};
    let mut hasher = state.build_hasher();
    let mut ranges = Vec::with_capacity(keys.len());
    for key in keys {
        if let Some((start, end)) = extract_join_key_range(doc, key) {
            hasher.write(&doc[start..end]);
            ranges.push((start, end));
        } else {
            // Missing field — hash a sentinel.
            hasher.write_u8(0xc0); // NIL tag
            ranges.push((0, 0));
        }
    }
    (hasher.finish(), ranges)
}

fn extract_join_key_range(doc: &[u8], key: &str) -> Option<(usize, usize)> {
    msgpack_scan::extract_field(doc, 0, key).or_else(|| {