[Python] Support replace during create_index (#233)

Closes #214

python/lancedb/table.py

@@ -188,13 +188,15 @@ class LanceTable:
         num_partitions=256,
         num_sub_vectors=96,
         vector_column_name=VECTOR_COLUMN_NAME,
+        replace: bool = True,
     ):
         """Create an index on the table.
 
         Parameters
         ----------
         metric: str, default "L2"
-            The distance metric to use when creating the index. Valid values are "L2" or "cosine".
+            The distance metric to use when creating the index.
+            Valid values are "L2", "cosine", or "dot".
             L2 is euclidean distance.
         num_partitions: int
             The number of IVF partitions to use when creating the index.
@@ -202,6 +204,11 @@ class LanceTable:
         num_sub_vectors: int
             The number of PQ sub-vectors to use when creating the index.
             Default is 96.
+        vector_column_name: str, default "vector"
+            The vector column name to create the index.
+        replace: bool, default True
+            If True, replace the existing index if it exists.
+            If False, raise an error if duplicate index exists.
         """
         self._dataset.create_index(
             column=vector_column_name,
@@ -209,6 +216,7 @@ class LanceTable:
             metric=metric,
             num_partitions=num_partitions,
             num_sub_vectors=num_sub_vectors,
+            replace=replace,
         )
         self._reset_dataset()
 

python/tests/test_db.py

@@ -11,6 +11,7 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
+import numpy as np
 import pandas as pd
 import pytest
 
@@ -120,3 +121,31 @@ def test_delete_table(tmp_path):
 
     db.create_table("test", data=data)
     assert db.table_names() == ["test"]
+
+
+def test_replace_index(tmp_path):
+    db = lancedb.connect(uri=tmp_path)
+    table = db.create_table(
+        "test",
+        [
+            {"vector": np.random.rand(128), "item": "foo", "price": float(i)}
+            for i in range(1000)
+        ],
+    )
+    table.create_index(
+        num_partitions=2,
+        num_sub_vectors=4,
+    )
+
+    with pytest.raises(Exception):
+        table.create_index(
+            num_partitions=2,
+            num_sub_vectors=4,
+            replace=False,
+        )
+
+    table.create_index(
+        num_partitions=2,
+        num_sub_vectors=4,
+        replace=True,
+    )

python/tests/test_table.py

@@ -164,6 +164,7 @@ def test_create_index_method():
                 num_partitions=256,
                 num_sub_vectors=96,
                 vector_column_name="vector",
+                replace=True,
             )
 
             # Check that the _dataset.create_index method was called with the right parameters
@@ -173,4 +174,5 @@ def test_create_index_method():
                 metric="L2",
                 num_partitions=256,
                 num_sub_vectors=96,
+                replace=True,
             )