routier-collection / core/src / hashJoin
Function: hashJoin()
hashJoin(
options):JoinTuple[]
Defined in: core/src/plugins/query/join.ts:178
The join itself: one hash join, written once, called from every interpreter.
O(n + m) rather than a nested loop, which is the whole reason the API takes explicit key selectors instead of a free-form predicate. Both key properties are string or number by a build-time rule, so the keys are hashable and compare the same way in JS and in SQL.
Semantics, exactly as specs/joins.md states them:
- Null keys never match. Under
leftthe outer row still appears, paired withundefined. - Duplicates produce every pair: the full cross product per key group.
- Ordering is outer order, then inner order within a key group. Undefined by contract — a caller who cares sorts.