Function CallSubqueryConsume

src/execution_plan/ops/op_call_subquery.c:301–332

consumes a record from the lhs, plants it in the Argument\List op(s), and consumes a record from the body until depletion. in case the subquery is returning, merges the input (lhs) record with the output record. otherwise, the input record is passed as-is upon depletion of the body, repeats the above. depletion of lhs yields depletion of this operation

// upon depletion of the body, repeats the above. depletion of lhs yields
// depletion of this operation
static Record CallSubqueryConsume
(
	OpBase *opBase  // operation
) {
	OpCallSubquery *op = (OpCallSubquery *)opBase;

	// if there are more records to consume from body, consume them before
	// consuming another record from lhs
	if(op->r) {
		return _handoff(op);
	}
	ASSERT(op->r == NULL);

	// consume from lhs if exists, otherwise create a dummy-record to pass to
	// the body (rhs). the latter case will happen AT MOST once
	if(op->lhs) {
		op->r = OpBase_Consume(op->lhs);
	} else if(op->first) {
		op->r = OpBase_CreateRecord((OpBase *)op);
		op->first = false;
	}

	// plant the record consumed at the Argument ops
	if(op->r) {
		_plant_records_Arguments(op);
	} else {
		// no records - lhs depleted
		return NULL;
	}

	return _handoff(op);
}

// frees CallSubquery internal data structures
static void _free_records