@Override
  public boolean isSame(OperatorDesc other) {
    if (getClass().getName().equals(other.getClass().getName())) {
      TableScanDesc otherDesc = (TableScanDesc) other;
      return Objects.equals(getQualifiedTable(), otherDesc.getQualifiedTable()) &&
          ExprNodeDescUtils.isSame(getFilterExpr(), otherDesc.getFilterExpr()) &&
          getRowLimit() == otherDesc.getRowLimit() &&
          isGatherStats() == otherDesc.isGatherStats();
    }
    return false;
  }
A boolean variable set to true by the semantic analyzer only in case of the analyze command.
ql/src/java/org/apache/hadoop/hive/ql/plan/TableScanDesc.java