diff --git a/mlem/api/commands.py b/mlem/api/commands.py
index f574164b..f3d5c757 100644
--- a/mlem/api/commands.py
+++ b/mlem/api/commands.py
@@ -91,7 +91,9 @@ def apply(
             batch_data = get_data_value(part, batch_size)
             for batch in batch_data:
                 preds = w.call_method(resolved_method, batch.data)
-                res += [*preds]  # TODO: merge results
+                res.append(preds)
+        dt = w.methods[resolved_method].returns
+        res = dt.combine(res)
     else:
         res = [
             w.call_method(resolved_method, get_data_value(part))
diff --git a/mlem/contrib/lightgbm.py b/mlem/contrib/lightgbm.py
index b45fad44..ee2537f9 100644
--- a/mlem/contrib/lightgbm.py
+++ b/mlem/contrib/lightgbm.py
@@ -75,6 +75,9 @@ def process(cls, obj: Any, **kwargs) -> DataType:
     def get_model(self, prefix: str = "") -> Type[BaseModel]:
         return self.inner.get_serializer().get_model(prefix)
 
+    def combine(self, batched_data: List[lgb.Dataset]) -> lgb.Dataset:
+        raise NotImplementedError
+
 
 class LightGBMDataWriter(DataWriter):
     type: ClassVar[str] = "lightgbm"
diff --git a/mlem/contrib/numpy.py b/mlem/contrib/numpy.py
index 63169805..88000124 100644
--- a/mlem/contrib/numpy.py
+++ b/mlem/contrib/numpy.py
@@ -12,7 +12,11 @@
     DataType,
     DataWriter,
 )
-from mlem.core.errors import DeserializationError, SerializationError
+from mlem.core.errors import (
+    DeserializationError,
+    InvalidDatatypeForBatchLoading,
+    SerializationError,
+)
 from mlem.core.requirements import LibRequirementsMixin
 
 
@@ -79,6 +83,9 @@ def get_writer(self, project: str = None, filename: str = None, **kwargs):
     def get_model(self, prefix: str = "") -> Type:
         return python_type_from_np_string_repr(self.dtype)
 
+    def combine(self, batched_data: List[np.number]) -> np.number:
+        raise NotImplementedError
+
 
 class NumpyNdarrayType(
     LibRequirementsMixin, DataType, DataHook, DataSerializer
@@ -101,6 +108,17 @@ class NumpyNdarrayType(
     def _abstract_shape(shape):
         return (None,) + shape[1:]
 
+    def combine(self, batched_data: List[np.ndarray]) -> np.ndarray:
+        is_valid_type = all(
+            self.is_object_valid(elem) for elem in batched_data
+        )
+        if not is_valid_type:
+            raise InvalidDatatypeForBatchLoading(
+                f"Expected all values to be {self.type} for batch-loading."
+            )
+
+        return np.concatenate(batched_data, axis=0)
+
     @classmethod
     def process(cls, obj, **kwargs) -> DataType:
         return NumpyNdarrayType(
diff --git a/mlem/contrib/pandas.py b/mlem/contrib/pandas.py
index 3a62a4a8..8cb6936f 100644
--- a/mlem/contrib/pandas.py
+++ b/mlem/contrib/pandas.py
@@ -217,6 +217,9 @@ def serialize(self, instance: pd.DataFrame):
 
         return {"values": (instance.to_dict("records"))}
 
+    def combine(self, batched_data: List[pd.DataFrame]) -> pd.DataFrame:
+        raise NotImplementedError
+
 
 class SeriesType(_PandasDataType):
     """
diff --git a/mlem/contrib/torch.py b/mlem/contrib/torch.py
index c2b373b1..ce85a210 100644
--- a/mlem/contrib/torch.py
+++ b/mlem/contrib/torch.py
@@ -97,6 +97,9 @@ def process(cls, obj: torch.Tensor, **kwargs) -> DataType:
             dtype=str(obj.dtype)[len("torch") + 1 :],
         )
 
+    def combine(self, batched_data: List[torch.Tensor]) -> torch.Tensor:
+        raise NotImplementedError
+
 
 class TorchTensorWriter(DataWriter):
     type: ClassVar[str] = "torch"
diff --git a/mlem/contrib/xgboost.py b/mlem/contrib/xgboost.py
index c7db3fe8..a0503984 100644
--- a/mlem/contrib/xgboost.py
+++ b/mlem/contrib/xgboost.py
@@ -111,6 +111,9 @@ def get_writer(
     def get_model(self, prefix: str = "") -> Type[BaseModel]:
         raise NotImplementedError
 
+    def combine(self, batched_data: List[xgboost.DMatrix]) -> xgboost.DMatrix:
+        raise NotImplementedError
+
 
 class XGBoostModelIO(ModelIO):
     """
diff --git a/mlem/core/data_type.py b/mlem/core/data_type.py
index 4356fbf9..7b552b3d 100644
--- a/mlem/core/data_type.py
+++ b/mlem/core/data_type.py
@@ -14,6 +14,7 @@
     Sized,
     Tuple,
     Type,
+    TypeVar,
     Union,
 )
 
@@ -28,6 +29,8 @@
 from mlem.core.requirements import Requirements, WithRequirements
 from mlem.utils.module import get_object_requirements
 
+T = TypeVar("T")
+
 
 class DataType(ABC, MlemABC, WithRequirements):
     """
@@ -52,6 +55,10 @@ def check_type(obj, exp_type, exc_type):
     def get_requirements(self) -> Requirements:
         return get_object_requirements(self)
 
+    @abstractmethod
+    def combine(self, batched_data: List[T]) -> T:
+        raise NotImplementedError
+
     @abstractmethod
     def get_writer(
         self, project: str = None, filename: str = None, **kwargs
@@ -112,10 +119,16 @@ def get_writer(
     def get_model(self, prefix: str = "") -> Type[BaseModel]:
         raise NotImplementedError
 
+    def combine(self, batched_data: List[T]) -> T:
+        raise NotImplementedError
+
 
 class DataHook(Hook[DataType], ABC):
     """Base class for hooks to analyze data objects"""
 
+    def combine(self, batched_data: List[T]) -> T:
+        raise NotImplementedError
+
 
 class DataAnalyzer(Analyzer):
     """Analyzer for data objects"""
@@ -200,6 +213,9 @@ def get_requirements(self) -> Requirements:
     def get_model(self, prefix: str = "") -> Type[BaseModel]:
         return self.to_type
 
+    def combine(self, batched_data: List[Any]) -> Any:
+        raise NotImplementedError
+
 
 class PrimitiveWriter(DataWriter):
     type: ClassVar[str] = "primitive"
@@ -267,6 +283,9 @@ def get_model(self, prefix: str = "") -> Type[BaseModel]:
             __root__=(List[self.dtype.get_serializer().get_model(subname)], ...),  # type: ignore
         )
 
+    def combine(self, batched_data: List[T]) -> T:
+        raise NotImplementedError
+
 
 class ArrayWriter(DataWriter):
     type: ClassVar[str] = "array"
@@ -364,6 +383,9 @@ def get_model(self, prefix: str = "") -> Type[BaseModel]:
             ),
         )
 
+    def combine(self, batched_data: List[Any]) -> Any:
+        raise NotImplementedError
+
 
 def _check_type_and_size(obj, dtype, size, exc_type):
     DataType.check_type(obj, dtype, exc_type)
@@ -532,6 +554,9 @@ def get_model(self, prefix="") -> Type[BaseModel]:
         }
         return create_model(prefix + "DictType", **kwargs)  # type: ignore
 
+    def combine(self, batched_data: List[T]) -> T:
+        raise NotImplementedError
+
 
 class DictWriter(DataWriter):
     type: ClassVar[str] = "dict"
diff --git a/mlem/core/errors.py b/mlem/core/errors.py
index 7b2a5aaf..b0fee8bf 100644
--- a/mlem/core/errors.py
+++ b/mlem/core/errors.py
@@ -91,6 +91,10 @@ class UnsupportedDataBatchLoading(MlemError):
     """Thrown if batch loading of data is called for import workflow"""
 
 
+class InvalidDatatypeForBatchLoading(MlemError):
+    """Thrown if batch loading of dataset has incorrect types"""
+
+
 class WrongMethodError(ValueError, MlemError):
     """Thrown if wrong method name for model is provided"""
 
diff --git a/mlem/runtime/interface.py b/mlem/runtime/interface.py
index e526b517..6eec047d 100644
--- a/mlem/runtime/interface.py
+++ b/mlem/runtime/interface.py
@@ -25,7 +25,7 @@ class InterfaceDescriptor(BaseModel):
 
 class Interface(ABC, MlemABC):
     """Base class for runtime interfaces.
-    Describes a set of methods togerher with their signatures (arguments
+    Describes a set of methods together with their signatures (arguments
     and return type) and executors - actual python callables to be run
     when the method is invoked. Used to setup `Server`"""
 
diff --git a/tests/cli/test_apply.py b/tests/cli/test_apply.py
index 76af85f2..fd8e40ef 100644
--- a/tests/cli/test_apply.py
+++ b/tests/cli/test_apply.py
@@ -9,7 +9,7 @@
 from sklearn.tree import DecisionTreeClassifier
 
 from mlem.api import load, save
-from mlem.core.data_type import ArrayType
+from mlem.contrib.numpy import NumpyNdarrayType
 from mlem.core.errors import MlemProjectNotFound
 from mlem.core.metadata import load_meta
 from mlem.core.objects import MlemData
@@ -89,9 +89,9 @@ def test_apply_batch(runner, model_path_batch, data_path_batch):
         predictions_meta = load_meta(
             path, load_value=True, force_type=MlemData
         )
-        assert isinstance(predictions_meta.data_type, ArrayType)
+        assert isinstance(predictions_meta.dataset, NumpyNdarrayType)
         predictions = predictions_meta.get_value()
-        assert isinstance(predictions, list)
+        assert isinstance(predictions, ndarray)
 
 
 def test_apply_with_import(runner, model_meta_saved_single, tmp_path_factory):
diff --git a/tests/runtime/test_interface.py b/tests/runtime/test_interface.py
index 856dddd0..991aeb75 100644
--- a/tests/runtime/test_interface.py
+++ b/tests/runtime/test_interface.py
@@ -1,4 +1,4 @@
-from typing import Any, ClassVar
+from typing import Any, ClassVar, List
 
 import pytest
 
@@ -30,6 +30,9 @@ def get_writer(
     ) -> DataWriter:
         raise NotImplementedError
 
+    def combine(self, batched_data: List[Any]) -> Any:
+        raise NotImplementedError
+
 
 @pytest.fixture
 def interface() -> Interface: