synchronized public static HiveDefaultCostModel getCostModel() {
    if (INSTANCE == null) {
      INSTANCE = new HiveDefaultCostModel();
    }

    return INSTANCE;
  }
Default implementation of the cost model.
Currently used by MR execution engine.
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/cost/HiveDefaultCostModel.java