address feedback

integrations/pgvector/src/haystack_integrations/document_stores/pgvector/document_store.py

@@ -168,7 +168,7 @@ def delete_table(self):
 
         delete_sql = SQL("DROP TABLE IF EXISTS {table_name}").format(table_name=Identifier(self.table_name))
 
-        self._execute_sql(delete_sql, error_msg="Could not delete table in PgvectorDocumentStore")
+        self._execute_sql(delete_sql, error_msg=f"Could not delete table {self.table_name} in PgvectorDocumentStore")
 
     def _handle_hnsw(self):
         """
@@ -193,7 +193,8 @@ def _handle_hnsw(self):
         if index_esists and not self.hnsw_recreate_index_if_exists:
             logger.warning(
                 "HNSW index already exists and won't be recreated. "
-                "If you want to recreate it, set hnsw_recreate_index=True"
+                "If you want to recreate it, pass 'hnsw_recreate_index_if_exists=True' to the "
+                "Document Store constructor"
             )
             return
 
@@ -208,7 +209,7 @@ def _create_hnsw_index(self):
         """
 
         pg_ops = SIMILARITY_FUNCTION_TO_POSTGRESQL_OPS[self.embedding_similarity_function]
-        effective_hnsw_index_creation_kwargs = {
+        actual_hnsw_index_creation_kwargs = {
             key: value
             for key, value in self.hnsw_index_creation_kwargs.items()
             if key in HNSW_INDEX_CREATION_VALID_KWARGS
@@ -218,12 +219,12 @@ def _create_hnsw_index(self):
             index_name=Identifier(HNSW_INDEX_NAME), table_name=Identifier(self.table_name), ops=SQL(pg_ops)
         )
 
-        if effective_hnsw_index_creation_kwargs:
-            effective_hnsw_index_creation_kwargs_str = ", ".join(
-                f"{key} = {value}" for key, value in effective_hnsw_index_creation_kwargs.items()
+        if actual_hnsw_index_creation_kwargs:
+            actual_hnsw_index_creation_kwargs_str = ", ".join(
+                f"{key} = {value}" for key, value in actual_hnsw_index_creation_kwargs.items()
             )
             sql_add_creation_kwargs = SQL("WITH ({creation_kwargs_str})").format(
-                creation_kwargs_str=SQL(effective_hnsw_index_creation_kwargs_str)
+                creation_kwargs_str=SQL(actual_hnsw_index_creation_kwargs_str)
             )
             sql_create_index += sql_add_creation_kwargs
 
@@ -275,8 +276,8 @@ def write_documents(self, documents: List[Document], policy: DuplicatePolicy = D
 
         db_documents = self._from_haystack_to_pg_documents(documents)
 
-        columns_str = "(" + ", ".join(col for col, *_ in COLUMNS) + ")"
-        values_placeholder_str = "VALUES (" + ", ".join(f"%({col})s" for col, *_ in COLUMNS) + ")"
+        columns_str = "(" + ", ".join(col for col in COLUMNS) + ")"
+        values_placeholder_str = "VALUES (" + ", ".join(f"%({col})s" for col in COLUMNS) + ")"
 
         insert_statement = SQL("INSERT INTO {table_name} " + columns_str + " " + values_placeholder_str).format(
             table_name=Identifier(self.table_name)
@@ -285,7 +286,7 @@ def write_documents(self, documents: List[Document], policy: DuplicatePolicy = D
         if policy == DuplicatePolicy.OVERWRITE:
             update_statement = SQL(
                 "ON CONFLICT (id) DO UPDATE SET "
-                + ", ".join(f"{col} = EXCLUDED.{col}" for col, *_ in COLUMNS if col != "id")
+                + ", ".join(f"{col} = EXCLUDED.{col}" for col in COLUMNS if col != "id")
             )
             insert_statement += update_statement
         elif policy == DuplicatePolicy.SKIP:
@@ -347,6 +348,9 @@ def _from_pg_to_haystack_documents(self, documents: List[Dict[str, Any]]) -> Lis
             blob_meta = haystack_dict.pop("blob_meta")
             blob_mime_type = haystack_dict.pop("blob_mime_type")
 
+            if not haystack_dict["meta"]:
+                haystack_dict["meta"] = {}
+
             haystack_document = Document.from_dict(haystack_dict)
 
             if blob_data: