@Override
  public TableFunctionScan copy(RelTraitSet traitSet, List<RelNode> inputs, RexNode rexCall,
      Type elementType, RelDataType rowType, Set<RelColumnMapping> columnMappings) {
    return new HiveTableFunctionScan(getCluster(), traitSet, inputs, rexCall,
        elementType, rowType, columnMappings);
  }
@param cluster
         cluster - Cluster that this relational expression belongs to
@param traitSet
@param inputs
         inputs - 0 or more relational inputs
@param rexCall
         rexCall - Function invocation expression
@param elementType
         elementType - Element type of the collection that will implement
         this table
@param rowType
         rowType - Row type produced by function
@param columnMappings
         columnMappings - Column mappings associated with this function
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/reloperators/HiveTableFunctionScan.java