Bug fix Weaviate document deletion (#2899)

* Bug fix Weaviate document deletion

If no filters param is passed in, then the original code retrieves *all* documents before then deleting by their IDs. There's no need for that, since we can delete by their IDs directly.

* Edit comment to clarify deletion and recreation

* Write unit tests for bug fix

haystack/document_stores/weaviate.py

@@ -1299,10 +1299,19 @@ class WeaviateDocumentStore(BaseDocumentStore):
         index = self._sanitize_index_name(index) or self.index
 
         if not filters and not ids:
+            # Delete the existing index, then create an empty new one
             self._create_schema_and_index(index, recreate_index=True)
+            return
+
+        # Create index if it doesn't exist yet
+        self._create_schema_and_index(index, recreate_index=False)
+
+        if ids and not filters:
+            for id in ids:
+                self.weaviate_client.data_object.delete(id)
+
         else:
-            # create index if it doesn't exist yet
-            self._create_schema_and_index(index, recreate_index=False)
+            # Use filters to restrict list of retrieved documents, before checking these against provided ids
             docs_to_delete = self.get_all_documents(index, filters=filters)
             if ids:
                 docs_to_delete = [doc for doc in docs_to_delete if doc.id in ids]

test/document_stores/test_weaviate.py

@@ -1,4 +1,5 @@
 import uuid
+from unittest.mock import MagicMock
 
 import numpy as np
 import pytest
@@ -6,7 +7,6 @@ import pytest
 from haystack.schema import Document
 from ..conftest import get_document_store
 
-
 embedding_dim = 768
 
 
@@ -123,3 +123,24 @@ def test_get_all_documents_unaffected_by_QUERY_MAXIMUM_RESULTS(document_store_wi
     monkeypatch.setattr(document_store_with_docs, "get_document_count", lambda **kwargs: 13_000)
     docs = document_store_with_docs.get_all_documents()
     assert len(docs) == 3
+
+
+@pytest.mark.weaviate
+@pytest.mark.parametrize("document_store_with_docs", ["weaviate"], indirect=True)
+def test_deleting_by_id_or_by_filters(document_store_with_docs):
+    # This test verifies that deleting an object by its ID does not first require fetching all documents. This fixes
+    # a bug, as described in https://github.com/deepset-ai/haystack/issues/2898
+    document_store_with_docs.get_all_documents = MagicMock(wraps=document_store_with_docs.get_all_documents)
+
+    assert document_store_with_docs.get_document_count() == 3
+
+    # Delete a document by its ID. This should bypass the get_all_documents() call
+    document_store_with_docs.delete_documents(ids=[DOCUMENTS_XS[0]["id"]])
+    document_store_with_docs.get_all_documents.assert_not_called()
+    assert document_store_with_docs.get_document_count() == 2
+
+    document_store_with_docs.get_all_documents.reset_mock()
+    # Delete a document with filters. Prove that using the filters will go through get_all_documents()
+    document_store_with_docs.delete_documents(filters={"name": ["filename2"]})
+    document_store_with_docs.get_all_documents.assert_called()
+    assert document_store_with_docs.get_document_count() == 1