code: public static List<String> generateAlterTableOrPartitionStorageFormatDDL(final String dbName,
        final String tableName,
        final Optional<Map<String, String>> partitionsDMLInfo,
        String format) {
      Preconditions.checkArgument(StringUtils.isNotBlank(tableName), "Table name should not be empty");
      Preconditions.checkArgument(StringUtils.isNotBlank(format), "Format should not be empty");
  
      // Resolve defaults
      String resolvedDbName = (StringUtils.isBlank(dbName)) ? DEFAULT_DB_NAME : dbName;
  
      // Partition details
      StringBuilder partitionSpecs = new StringBuilder();
  
      if (partitionsDMLInfo.isPresent()) {
        partitionSpecs.append("PARTITION (");
        boolean isFirstPartitionSpec = true;
        for (Map.Entry<String, String> partition : partitionsDMLInfo.get().entrySet()) {
          if (isFirstPartitionSpec) {
            isFirstPartitionSpec = false;
          } else {
            partitionSpecs.append(", ");
          }
          partitionSpecs.append(String.format("`%s`='%s'", partition.getKey(), partition.getValue()));
        }
        partitionSpecs.append(") ");
      }
  
      List<String> ddls = Lists.newArrayList();
  
  
      // Note: Hive does not support fully qualified Hive table names such as db.table for ALTER TABLE in v0.13
      // .. hence specifying 'use dbName' as a precursor to rename
      // Refer: HIVE-2496
      ddls.add(String.format("USE %s%n", resolvedDbName));
      ddls.add(String.format("ALTER TABLE %s %s SET FILEFORMAT %s", tableName, partitionSpecs, format));
  
      return ddls;
    }
docs: *
  Generate DDL for updating file format of table or partition.
  If partition spec is absent, DDL query to change storage format of Table is generated.
  
  Query syntax:
  <p>
  ALTER TABLE tableName [PARTITION partition_spec] SET FILEFORMAT fileFormat
  </p>
  
  @param dbName            Database for the table for which storage format needs to be changed.
  @param tableName         Table for which storage format needs to be changed.
  @param partitionsDMLInfo Optional partition spec for which storage format needs to be changed.
  @param format            Storage format.
  @return DDL to change storage format for Table or Partition.