private ASTNode buildSelExprSubTree(String tableAlias, String col) {
    tableAlias = StringInternUtils.internIfNotNull(tableAlias);
    col = StringInternUtils.internIfNotNull(col);
    ASTNode selexpr = new ASTNode(SELEXPR_TOKEN);
    ASTNode tableOrCol = new ASTNode(TABLEORCOL_TOKEN);
    ASTNode dot = new ASTNode(DOT_TOKEN);
    tableOrCol.addChild(new ASTNode(new CommonToken(HiveParser.Identifier, tableAlias)));
    dot.addChild(tableOrCol);
    dot.addChild(new ASTNode(new CommonToken(HiveParser.Identifier, col)));
    selexpr.addChild(dot);
    return selexpr;
  }
Construct the data structures containing ExprNodeDesc for partition
columns and order columns. Use the input definition to construct the list
of output columns for the ReduceSinkOperator
ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java