public void delete(CassandraPersistenceSession session, EventSubscriptionEntity entity) {
    session.addStatement(
        QueryBuilder.delete()
            .mapElt("event_subscriptions", entity.getId())
            .from(ProcessInstanceTableHandler.TABLE_NAME)
            .where(eq("id", entity.getProcessInstanceId())),
        entity.getProcessInstanceId());

    for (IndexHandler<EventSubscriptionEntity> index : indexHandlers.values()) {
      session.addIndexStatement(
          index.getDeleteStatement(session, entity), entity.getProcessInstanceId());
    }
  }
  protected Statement createUpdateStatement(
      CassandraPersistenceSession session, EventSubscriptionEntity entity) {
    Session s = session.getSession();
    UDTypeHandler typeHander = session.getTypeHander(EventSubscriptionEntity.class);
    CassandraSerializer<EventSubscriptionEntity> serializer =
        session.getSerializer(EventSubscriptionEntity.class);

    UDTValue value = typeHander.createValue(s);
    serializer.write(value, entity);

    return QueryBuilder.update(ProcessInstanceTableHandler.TABLE_NAME)
        .with(put("event_subscriptions", entity.getId(), value))
        .where(eq("id", entity.getProcessInstanceId()));
  }
  public LoadedCompositeEntity getEntityById(CassandraPersistenceSession session, String id) {
    LoadedCompositeEntity loadedProcessInstance = new LoadedCompositeEntity();

    Session s = session.getSession();

    Row row = s.execute(select().all().from(TABLE_NAME).where(eq("id", id))).one();
    if (row == null) {
      return null;
    }

    int version = row.getInt("version");
    String businessKey = row.getString("business_key");

    CassandraSerializer<ExecutionEntity> executionSerializer =
        session.getSerializer(ExecutionEntity.class);
    CassandraSerializer<EventSubscriptionEntity> eventSubscriptionSerializer =
        session.getSerializer(EventSubscriptionEntity.class);
    CassandraSerializer<VariableInstanceEntity> variableSerializer =
        session.getSerializer(VariableInstanceEntity.class);

    // deserialize all executions
    Map<String, UDTValue> executionsMap = row.getMap(EXECUTIONS, String.class, UDTValue.class);
    Map<String, ExecutionEntity> executions = new HashMap<String, ExecutionEntity>();
    for (UDTValue serializedExecution : executionsMap.values()) {
      ExecutionEntity executionEntity = executionSerializer.read(serializedExecution);
      executions.put(executionEntity.getId(), executionEntity);
      if (executionEntity.isProcessInstanceExecution()) {
        loadedProcessInstance.setMainEntity(executionEntity);
      }
    }
    loadedProcessInstance.put(EXECUTIONS, executions);

    // deserialize all event subscription
    Map<String, UDTValue> eventSubscriptionsMap =
        row.getMap(EVENT_SUBSCRIPTIONS, String.class, UDTValue.class);
    Map<String, EventSubscriptionEntity> eventSubscriptions =
        new HashMap<String, EventSubscriptionEntity>();
    for (UDTValue serializedEventSubscription : eventSubscriptionsMap.values()) {
      EventSubscriptionEntity eventSubscriptionEntity =
          eventSubscriptionSerializer.read(serializedEventSubscription);
      eventSubscriptions.put(eventSubscriptionEntity.getId(), eventSubscriptionEntity);
    }
    loadedProcessInstance.put(EVENT_SUBSCRIPTIONS, eventSubscriptions);

    // deserialize all variables
    Map<String, UDTValue> variablesMap = row.getMap(VARIABLES, String.class, UDTValue.class);
    Map<String, VariableInstanceEntity> variables = new HashMap<String, VariableInstanceEntity>();
    for (UDTValue serializedVariable : variablesMap.values()) {
      VariableInstanceEntity variableEntity = variableSerializer.read(serializedVariable);
      variables.put(variableEntity.getId(), variableEntity);
    }
    loadedProcessInstance.put(VARIABLES, variables);

    reconstructEntityTree(loadedProcessInstance);

    ExecutionEntity processInstance = (ExecutionEntity) loadedProcessInstance.getPrimaryEntity();
    processInstance.setRevision(version);
    processInstance.setBusinessKey(businessKey);

    ProcessInstanceBatch batch =
        new ProcessInstanceBatch((ExecutionEntity) loadedProcessInstance.getPrimaryEntity());
    LOG.fine(
        "Loaded process instance, id="
            + processInstance.getId()
            + ", version="
            + processInstance.getRevision());
    session.addLockedBatch(loadedProcessInstance.getPrimaryEntity().getId(), batch);

    return loadedProcessInstance;
  }