presto-main/src/main/java/io/prestosql/cost/JoinStatsRule.java/JoinStatsRule/computeLeftJoinStats
class JoinStatsRule:    private PlanNodeStatsEstimate computeLeftJoinStats(
            JoinNode node,
            PlanNodeStatsEstimate leftStats,
            PlanNodeStatsEstimate rightStats,
            PlanNodeStatsEstimate crossJoinStats,
            Session session,
            TypeProvider types)
    {
        PlanNodeStatsEstimate innerJoinStats = computeInnerJoinStats(node, crossJoinStats, session, types);
        PlanNodeStatsEstimate leftJoinComplementStats = calculateJoinComplementStats(node.getFilter(), node.getCriteria(), leftStats, rightStats, types);
        return addJoinComplementStats(
                leftStats,
                innerJoinStats,
                leftJoinComplementStats);
    }