protected static boolean isConfigEnabled(Cluster cluster, String configType, String propertyName) {
    boolean isRangerPluginEnabled = false;
    if (cluster != null) {
      Config rangerPluginProperties = cluster.getDesiredConfigByType(configType);
      if (rangerPluginProperties != null) {
        String rangerPluginEnabled = rangerPluginProperties.getProperties().get(propertyName);
        if (StringUtils.isNotEmpty(rangerPluginEnabled)) {
          isRangerPluginEnabled =  "yes".equalsIgnoreCase(rangerPluginEnabled);
        }
      }
    }
    return isRangerPluginEnabled;
  }
Fetches the maximum value of the given ID column from the given table.

@param tableName
         the name of the table to query the data from
@param idColumnName
         the name of the ID column you want to query the maximum value for.
         This MUST refer an existing numeric type column
@return the maximum value of the given column in the given table if any;
        <code>0L</code> otherwise.
@throws SQLException
ambari-server/src/main/java/org/apache/ambari/server/upgrade/AbstractUpgradeCatalog.java