public static void processUniqueConstraints(TableName tableName, ASTNode child,
      List<SQLUniqueConstraint> uniqueConstraints) throws SemanticException {
    List<ConstraintInfo> uniqueInfos = generateConstraintInfos(child);
    constraintInfosToUniqueConstraints(tableName, uniqueInfos, uniqueConstraints);
  }
Process the unique constraints from the ast node and populate the SQLUniqueConstraint list.
ql/src/java/org/apache/hadoop/hive/ql/ddl/table/constraint/ConstraintsUtils.java