/**
   * @param rmtReducer Optional reducer.
   * @param rmtTransform Optional transformer.
   * @param args Arguments.
   * @return Future.
   */
  @SuppressWarnings("IfMayBeConditional")
  private <R> CacheQueryFuture<R> execute(
      @Nullable IgniteReducer<T, R> rmtReducer,
      @Nullable IgniteClosure<T, R> rmtTransform,
      @Nullable Object... args) {
    Collection<ClusterNode> nodes = nodes();

    cctx.checkSecurity(SecurityPermission.CACHE_READ);

    if (nodes.isEmpty())
      return new GridCacheQueryErrorFuture<>(
          cctx.kernalContext(), new ClusterGroupEmptyCheckedException());

    if (log.isDebugEnabled())
      log.debug("Executing query [query=" + this + ", nodes=" + nodes + ']');

    if (cctx.deploymentEnabled()) {
      try {
        cctx.deploy().registerClasses(filter, rmtReducer, rmtTransform);
        cctx.deploy().registerClasses(args);
      } catch (IgniteCheckedException e) {
        return new GridCacheQueryErrorFuture<>(cctx.kernalContext(), e);
      }
    }

    if (subjId == null) subjId = cctx.localNodeId();

    taskHash = cctx.kernalContext().job().currentTaskNameHash();

    final GridCacheQueryBean bean =
        new GridCacheQueryBean(
            this,
            (IgniteReducer<Object, Object>) rmtReducer,
            (IgniteClosure<Object, Object>) rmtTransform,
            args);

    final GridCacheQueryManager qryMgr = cctx.queries();

    boolean loc = nodes.size() == 1 && F.first(nodes).id().equals(cctx.localNodeId());

    if (type == SQL_FIELDS || type == SPI)
      return (CacheQueryFuture<R>)
          (loc ? qryMgr.queryFieldsLocal(bean) : qryMgr.queryFieldsDistributed(bean, nodes));
    else if (type == SCAN && part != null && nodes.size() > 1)
      return new CacheQueryFallbackFuture<>(nodes, bean, qryMgr);
    else
      return (CacheQueryFuture<R>)
          (loc ? qryMgr.queryLocal(bean) : qryMgr.queryDistributed(bean, nodes));
  }
  /**
   * @param rmtReducer Optional reducer.
   * @param rmtTransform Optional transformer.
   * @param args Arguments.
   * @return Future.
   */
  @SuppressWarnings("IfMayBeConditional")
  private <R> GridCacheQueryFuture<R> execute(
      @Nullable GridReducer<T, R> rmtReducer,
      @Nullable GridClosure<T, R> rmtTransform,
      @Nullable Object... args) {
    Collection<GridNode> nodes = nodes();

    cctx.checkSecurity(GridSecurityPermission.CACHE_READ);

    if (F.isEmpty(nodes))
      return new GridCacheQueryErrorFuture<>(
          cctx.kernalContext(),
          new GridEmptyProjectionException("There are no data nodes for cache: " + cctx.namexx()));

    if (log.isDebugEnabled())
      log.debug("Executing query [query=" + this + ", nodes=" + nodes + ']');

    if (cctx.deploymentEnabled()) {
      try {
        cctx.deploy().registerClasses(filter, rmtReducer, rmtTransform);
        cctx.deploy().registerClasses(args);
      } catch (GridException e) {
        return new GridCacheQueryErrorFuture<>(cctx.kernalContext(), e);
      }
    }

    if (subjId == null) subjId = cctx.localNodeId();

    taskHash = cctx.kernalContext().job().currentTaskNameHash();

    GridCacheQueryBean bean =
        new GridCacheQueryBean(
            this,
            (GridReducer<Object, Object>) rmtReducer,
            (GridClosure<Object, Object>) rmtTransform,
            args);

    GridCacheQueryManager qryMgr = cctx.queries();

    boolean loc = nodes.size() == 1 && F.first(nodes).id().equals(cctx.localNodeId());

    if (type == SQL_FIELDS)
      return (GridCacheQueryFuture<R>)
          (loc ? qryMgr.queryFieldsLocal(bean) : qryMgr.queryFieldsDistributed(bean, nodes));
    else
      return (GridCacheQueryFuture<R>)
          (loc ? qryMgr.queryLocal(bean) : qryMgr.queryDistributed(bean, nodes));
  }
  /**
   * @param res Query result.
   * @param err Error or {@code null} if query executed successfully.
   * @param startTime Start time.
   * @param duration Duration.
   */
  public void onExecuted(Object res, Throwable err, long startTime, long duration) {
    boolean fail = err != null;

    // Update own metrics.
    metrics.onQueryExecute(duration, fail);

    // Update metrics in query manager.
    cctx.queries().onMetricsUpdate(duration, fail);

    if (log.isDebugEnabled())
      log.debug(
          "Query execution finished [qry="
              + this
              + ", startTime="
              + startTime
              + ", duration="
              + duration
              + ", fail="
              + fail
              + ", res="
              + res
              + ']');
  }