public static void processCheckConstraints(TableName tableName, ASTNode child, List<String> columnNames,
      List<SQLCheckConstraint> checkConstraints, final ASTNode typeChild, final TokenRewriteStream tokenRewriteStream)
      throws SemanticException {
    List<ConstraintInfo> checkInfos = generateConstraintInfos(child, columnNames, typeChild, tokenRewriteStream);
    constraintInfosToCheckConstraints(tableName, checkInfos, checkConstraints);
  }
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