private void updateBasicStatsState() {
    if (numRows <= 0 && dataSize <= 0) {
      this.basicStatsState = State.NONE;
    } else if (numRows <= 0 || dataSize <= 0) {
      this.basicStatsState = State.PARTIAL;
    } else {
      this.basicStatsState = State.COMPLETE;
    }
  }
Statistics. Describes the output of an operator in terms of size, rows, etc
based on estimates.
ql/src/java/org/apache/hadoop/hive/ql/plan/Statistics.java