add materialize stage

fiftyone/__public__.py

@@ -214,6 +214,7 @@
     MatchFrames,
     MatchLabels,
     MatchTags,
+    Materialize,
     Mongo,
     Select,
     SelectBy,

fiftyone/core/collections.py

@@ -291,6 +291,11 @@ def _is_clips(self):
         """Whether this collection contains clips."""
         raise NotImplementedError("Subclass must implement _is_clips")
 
+    @property
+    def _is_materialized(self):
+        """Whether this collection contains a materialized view."""
+        raise NotImplementedError("Subclass must implement _is_materialized")
+
     @property
     def _is_dynamic_groups(self):
         """Whether this collection contains dynamic groups."""
@@ -6193,6 +6198,33 @@ def match_tags(self, tags, bool=None, all=False):
         """
         return self._add_view_stage(fos.MatchTags(tags, bool=bool, all=all))
 
+    @view_stage
+    def materialize(self):
+        """Materializes the current view into a temporary database collection.
+
+        Apply this stage to an expensive view (eg an unindexed filtering
+        operation on a large dataset) if you plan to perform multiple
+        downstream operations on the view.
+
+        Examples::
+
+            import fiftyone as fo
+            import fiftyone.zoo as foz
+            from fiftyone import ViewField as F
+
+            dataset = foz.load_zoo_dataset("quickstart")
+
+            view = dataset.filter_labels("ground_truth", F("label") == "cat")
+            materialized_view = view.materialize()
+
+            print(view.count("ground_truth.detections"))
+            print(materialized_view.count("ground_truth.detections"))
+
+        Returns:
+            a :class:`fiftyone.core.view.DatasetView`
+        """
+        return self._add_view_stage(fos.Materialize())
+
     @view_stage
     def mongo(self, pipeline, _needs_frames=None, _group_slices=None):
         """Adds a view stage defined by a raw MongoDB aggregation pipeline.

fiftyone/core/dataset.py

@@ -426,7 +426,12 @@ def _root_dataset(self):
 
     @property
     def _is_generated(self):
-        return self._is_patches or self._is_frames or self._is_clips
+        return (
+            self._is_patches
+            or self._is_frames
+            or self._is_clips
+            or self._is_materialized
+        )
 
     @property
     def _is_patches(self):
@@ -442,6 +447,10 @@ def _is_frames(self):
     def _is_clips(self):
         return self._sample_collection_name.startswith("clips.")
 
+    @property
+    def _is_materialized(self):
+        return self._sample_collection_name.startswith("materialized.")
+
     @property
     def _is_dynamic_groups(self):
         return False
@@ -4877,7 +4886,13 @@ def clone(self, name=None, persistent=False):
         """
         return self._clone(name=name, persistent=persistent)
 
-    def _clone(self, name=None, persistent=False, view=None):
+    def _clone(
+        self,
+        name=None,
+        persistent=False,
+        view=None,
+        materialized=False,
+    ):
         if name is None:
             name = get_default_dataset_name()
 
@@ -4886,7 +4901,12 @@ def _clone(self, name=None, persistent=False, view=None):
         else:
             sample_collection = self
 
-        return _clone_collection(sample_collection, name, persistent)
+        return _clone_collection(
+            sample_collection,
+            name,
+            persistent=persistent,
+            materialized=materialized,
+        )
 
     def clear(self):
         """Removes all samples from the dataset.
@@ -8271,7 +8291,7 @@ def _clone_collection_indexes(
 
 
 def _make_sample_collection_name(
-    dataset_id, patches=False, frames=False, clips=False
+    dataset_id, patches=False, frames=False, clips=False, materialized=False
 ):
     if patches and frames:
         prefix = "patches.frames"
@@ -8281,6 +8301,8 @@ def _make_sample_collection_name(
         prefix = "frames"
     elif clips:
         prefix = "clips"
+    elif materialized:
+        prefix = "materialized"
     else:
         prefix = "samples"
 
@@ -8463,7 +8485,12 @@ def _delete_dataset_doc(dataset_doc):
     dataset_doc.delete()
 
 
-def _clone_collection(sample_collection, name, persistent):
+def _clone_collection(
+    sample_collection,
+    name,
+    persistent=False,
+    materialized=False,
+):
     slug = _validate_dataset_name(name)
 
     contains_videos = sample_collection._contains_videos(any_slice=True)
@@ -8490,7 +8517,9 @@ def _clone_collection(sample_collection, name, persistent):
     _id = dataset_doc.id
     now = datetime.utcnow()
 
-    sample_collection_name = _make_sample_collection_name(_id)
+    sample_collection_name = _make_sample_collection_name(
+        _id, materialized=materialized
+    )
 
     if contains_videos:
         frame_collection_name = _make_frame_collection_name(