community[patch]: Use newer MetadataVectorCassandraTable in Cassandra vector store (#15987)

as VectorTable is deprecated

Tested manually with `test_cassandra.py` vector store integration test.

libs/community/langchain_community/vectorstores/cassandra.py

@@ -75,7 +75,7 @@ class Cassandra(VectorStore):
         ttl_seconds: Optional[int] = None,
     ) -> None:
         try:
-            from cassio.vector import VectorTable
+            from cassio.table import MetadataVectorCassandraTable
         except (ImportError, ModuleNotFoundError):
             raise ImportError(
                 "Could not import cassio python package. "
@@ -90,11 +90,12 @@ class Cassandra(VectorStore):
         #
         self._embedding_dimension = None
         #
-        self.table = VectorTable(
+        self.table = MetadataVectorCassandraTable(
             session=session,
             keyspace=keyspace,
             table=table_name,
-            embedding_dimension=self._get_embedding_dimension(),
+            vector_dimension=self._get_embedding_dimension(),
+            metadata_indexing="all",
             primary_key_type="TEXT",
         )
 
@@ -127,7 +128,7 @@ class Cassandra(VectorStore):
         self.table.clear()
 
     def delete_by_document_id(self, document_id: str) -> None:
-        return self.table.delete(document_id)
+        return self.table.delete(row_id=document_id)
 
     def delete(self, ids: Optional[List[str]] = None, **kwargs: Any) -> Optional[bool]:
         """Delete by vector IDs.
@@ -188,7 +189,11 @@ class Cassandra(VectorStore):
 
             futures = [
                 self.table.put_async(
-                    text, embedding_vector, text_id, metadata, ttl_seconds
+                    row_id=text_id,
+                    body_blob=text,
+                    vector=embedding_vector,
+                    metadata=metadata or {},
+                    ttl_seconds=ttl_seconds,
                 )
                 for text, embedding_vector, text_id, metadata in zip(
                     batch_texts, batch_embedding_vectors, batch_ids, batch_metadatas
@@ -215,11 +220,10 @@ class Cassandra(VectorStore):
         """
         search_metadata = self._filter_to_metadata(filter)
         #
-        hits = self.table.search(
+        hits = self.table.metric_ann_search(
-            embedding_vector=embedding,
+            vector=embedding,
-            top_k=k,
+            n=k,
             metric="cos",
-            metric_threshold=None,
             metadata=search_metadata,
         )
         # We stick to 'cos' distance as it can be normalized on a 0-1 axis
@@ -227,11 +231,11 @@ class Cassandra(VectorStore):
         return [
             (
                 Document(
-                    page_content=hit["document"],
+                    page_content=hit["body_blob"],
                     metadata=hit["metadata"],
                 ),
                 0.5 + 0.5 * hit["distance"],
-                hit["document_id"],
+                hit["row_id"],
             )
             for hit in hits
         ]
@@ -340,31 +344,32 @@ class Cassandra(VectorStore):
         """
         search_metadata = self._filter_to_metadata(filter)
 
-        prefetchHits = self.table.search(
+        prefetch_hits = list(
-            embedding_vector=embedding,
+            self.table.metric_ann_search(
-            top_k=fetch_k,
+                vector=embedding,
+                n=fetch_k,
                 metric="cos",
-            metric_threshold=None,
                 metadata=search_metadata,
             )
+        )
         # let the mmr utility pick the *indices* in the above array
-        mmrChosenIndices = maximal_marginal_relevance(
+        mmr_chosen_indices = maximal_marginal_relevance(
             np.array(embedding, dtype=np.float32),
-            [pfHit["embedding_vector"] for pfHit in prefetchHits],
+            [pf_hit["vector"] for pf_hit in prefetch_hits],
             k=k,
             lambda_mult=lambda_mult,
         )
-        mmrHits = [
+        mmr_hits = [
-            pfHit
+            pf_hit
-            for pfIndex, pfHit in enumerate(prefetchHits)
+            for pf_index, pf_hit in enumerate(prefetch_hits)
-            if pfIndex in mmrChosenIndices
+            if pf_index in mmr_chosen_indices
         ]
         return [
             Document(
-                page_content=hit["document"],
+                page_content=hit["body_blob"],
                 metadata=hit["metadata"],
             )
-            for hit in mmrHits
+            for hit in mmr_hits
         ]
 
     def max_marginal_relevance_search(