code: private void deleteRelation(Object connection, EntityMetadata entityMetadata, String rowKey)
      {
          List<String> relations = entityMetadata.getRelationNames();
  
          if (relations != null)
          {
              for (String relation : relations)
              {
                  if (resource != null && resource.isActive())
                  {
                      ((Transaction) connection).hdel(getHashKey(entityMetadata.getTableName(), rowKey), relation);
  
                  }
                  else
                  {
                      ((Pipeline) connection).hdel(getHashKey(entityMetadata.getTableName(), rowKey), relation);
  
                  }
              }
  
          }
          /*
           * Response<Map<String, String>> fields = null; if (resource != null &&
           * resource.isActive()) { fields = ((Transaction)
           * connection).hgetAll(getHashKey(entityMetadata.getTableName(),
           * rowKey)); if (connection != null) { ((Pipeline) connection).sync(); }
           * for (String field : fields.get().keySet()) { ((Transaction)
           * connection).hdel(getHashKey(entityMetadata.getTableName(), rowKey),
           * field); } } else { fields = ((Pipeline)
           * connection).hgetAll(getHashKey(entityMetadata.getTableName(),
           * rowKey)); if (connection != null) { ((Pipeline) connection).sync(); }
           * for (String field : fields.get().keySet()) { ((Pipeline)
           * connection).hdel(getHashKey(entityMetadata.getTableName(), rowKey),
           * field); } }
           */
      }
docs: On delete relation.
  
  @param connection
  connection instance.
  @param entityMetadata
  entity metadata.
  @param rowKey
  row key.