Method getJoinAlgorithm

src/QueryPlan/JoinStep.h:171–171

    void setJoinAlgorithm(JoinAlgorithm join_algorithm_) { join_algorithm = join_algorithm_; }
    JoinAlgorithm getJoinAlgorithm() const { return join_algorithm; }

    /**
     * Hash Join don't support non-equivalent filter yet, so we must use nest loop join.