Struct JoinHashTable 

pub struct JoinHashTable { /* private fields */ }

A hash table for hash join operations with parallel build support.

Optimized with:

• ahash for fast integer hashing (3-5× faster than SipHash)
• Flat bucket design: HashMap<u64, Vec<(usize, usize)>> — no Value cloning in buckets
• Pre-sized hash map based on total build rows (zero reallocations)
• Bulk output construction instead of per-row set_value

Implementations

impl JoinHashTable

pub fn new(build_columns: Vec<u32>, probe_columns: Vec<u32>) -> Self

pub fn build( &self, build_chunks: &[DataChunk], ) -> HashMap<u64, Vec<(usize, usize)>>

Build phase: create a flat hash table mapping key hashes to (chunk_idx, row_idx) pairs. The hash table is pre-sized and uses ahash for fast integer hashing.

pub fn probe( &self, hash_table: &HashMap<u64, Vec<(usize, usize)>>, build_chunks: &[DataChunk], probe_chunks: &[DataChunk], ) -> OperatorResult

Probe phase: for each probe row, look up matching build rows by key hash, then verify key equality. Outputs combined build+probe columns.