feat(python): first cut batch queries for remote api (#753)

issue separate requests under the hood and concatenate results

python/lancedb/remote/table.py

@@ -11,6 +11,7 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
+import asyncio
 import uuid
 from functools import cached_property
 from typing import Dict, Optional, Union
@@ -227,8 +228,24 @@ class RemoteTable(Table):
         return LanceVectorQueryBuilder(self, query, vector_column_name)
 
     def _execute_query(self, query: Query) -> pa.Table:
-        result = self._conn._client.query(self._name, query)
-        return self._conn._loop.run_until_complete(result).to_arrow()
+        if (
+            query.vector is not None
+            and len(query.vector) > 0
+            and not isinstance(query.vector[0], float)
+        ):
+            futures = []
+            for v in query.vector:
+                v = list(v)
+                q = query.copy()
+                q.vector = v
+                futures.append(self._conn._client.query(self._name, q))
+            result = self._conn._loop.run_until_complete(asyncio.gather(*futures))
+            return pa.concat_tables(
+                [add_index(r.to_arrow(), i) for i, r in enumerate(result)]
+            )
+        else:
+            result = self._conn._client.query(self._name, query)
+            return self._conn._loop.run_until_complete(result).to_arrow()
 
     def delete(self, predicate: str):
         """Delete rows from the table.
@@ -342,3 +359,11 @@ class RemoteTable(Table):
         self._conn._loop.run_until_complete(
             self._conn._client.post(f"/v1/table/{self._name}/update/", data=payload)
         )
+
+
+def add_index(tbl: pa.Table, i: int) -> pa.Table:
+    return tbl.add_column(
+        0,
+        pa.field("query_index", pa.uint32()),
+        pa.array([i] * len(tbl), pa.uint32()),
+    )