invalidate cached dataset after create_index and add

python/lancedb/table.py

@@ -50,6 +50,12 @@ class LanceTable:
         self._conn = connection
         self.name = name
 
+    def _reset_dataset(self):
+        try:
+            del self.__dict__["_dataset"]
+        except AttributeError:
+            pass
+
     @property
     def schema(self) -> pa.Schema:
         """Return the schema of the table."""
@@ -92,12 +98,13 @@ class LanceTable:
             The number of PQ sub-vectors to use when creating the index.
             Default is 96.
         """
-        return self._dataset.create_index(
+        self._dataset.create_index(
             column=VECTOR_COLUMN_NAME,
             index_type="IVF_PQ",
             num_partitions=num_partitions,
             num_sub_vectors=num_sub_vectors,
         )
+        self._reset_dataset()
 
     @cached_property
     def _dataset(self) -> LanceDataset:
@@ -123,8 +130,9 @@ class LanceTable:
         The number of vectors added to the table.
         """
         data = _sanitize_data(data, self.schema)
-        ds = lance.write_dataset(data, self._dataset_uri, mode=mode)
-        return ds.count_rows()
+        lance.write_dataset(data, self._dataset_uri, mode=mode)
+        self._reset_dataset()
+        return len(self)
 
     def search(self, query: VEC) -> LanceQueryBuilder:
         """Create a search query to find the nearest neighbors

python/tests/test_table.py

@@ -99,14 +99,18 @@ def test_add(db):
 
     expected = pa.Table.from_arrays(
         [
-            pa.FixedSizeListArray.from_arrays(pa.array([3.1, 4.1, 5.9, 26.5]), 2),
-            pa.array(["foo", "bar"]),
-            pa.array([10.0, 20.0]),
+            pa.FixedSizeListArray.from_arrays(
+                pa.array([3.1, 4.1, 5.9, 26.5, 6.3, 100.5]), 2
+            ),
+            pa.array(["foo", "bar", "new"]),
+            pa.array([10.0, 20.0, 30.0]),
         ],
-        schema=pa.schema([
-            pa.field("vector", pa.list_(pa.float32(), 2)),
-            pa.field("item", pa.string()),
-            pa.field("price", pa.float64()),
-        ]),
+        schema=pa.schema(
+            [
+                pa.field("vector", pa.list_(pa.float32(), 2)),
+                pa.field("item", pa.string()),
+                pa.field("price", pa.float64()),
+            ]
+        ),
     )
     assert expected == table.to_arrow()