refactor emptiness check to be boolean, and optimize query

cognee/api/v1/search/search.py

@@ -8,7 +8,7 @@ from cognee.modules.search.types import SearchResult, SearchType, CombinedSearch
 from cognee.modules.users.methods import get_default_user
 from cognee.modules.search.methods import search as search_function
 from cognee.modules.data.methods import get_authorized_existing_datasets
-from cognee.modules.data.exceptions import DatasetNotFoundError, SearchOnEmptyGraphError
+from cognee.modules.data.exceptions import DatasetNotFoundError
 
 
 async def search(
@@ -177,12 +177,10 @@ async def search(
             raise DatasetNotFoundError(message="No datasets found.")
 
     graph_engine = await get_graph_engine()
-    nodes_count = await graph_engine.count_nodes()
+    is_empty = await graph_engine.is_empty()
 
-    if nodes_count == 0:
+    if is_empty:
-        raise SearchOnEmptyGraphError(
+        return []
-            message="Knowledge graph is empty, please ensure data is added and cognified."
-        )
 
     filtered_search_results = await search_function(
         query_text=query_text,

cognee/infrastructure/databases/graph/graph_db_interface.py

@@ -160,9 +160,9 @@ class GraphDBInterface(ABC):
     """
 
     @abstractmethod
-    async def count_nodes(self) -> int:
+    async def is_empty(self) -> bool:
-        logger.warning("count_nodes is not implemented")
+        logger.warning("is_empty() is not implemented")
-        return 1  # dummy value to not fail search()
+        return True
 
     @abstractmethod
     async def query(self, query: str, params: dict) -> List[Any]:

cognee/infrastructure/databases/graph/kuzu/adapter.py

@@ -185,13 +185,14 @@ class KuzuAdapter(GraphDBInterface):
         except FileNotFoundError:
             logger.warning(f"Kuzu S3 storage file not found: {self.db_path}")
 
-    async def count_nodes(self) -> int:
+    async def is_empty(self) -> bool:
         query = """
         MATCH (n)
-        RETURN COUNT(n);
+        RETURN true
+        LIMIT 1;
         """
         query_result = await self.query(query)
-        return query_result[0][0]
+        return len(query_result) == 0
 
     async def query(self, query: str, params: Optional[dict] = None) -> List[Tuple]:
         """

cognee/infrastructure/databases/graph/neo4j_driver/adapter.py

@@ -87,13 +87,14 @@ class Neo4jAdapter(GraphDBInterface):
         async with self.driver.session(database=self.graph_database_name) as session:
             yield session
 
-    async def count_nodes(self) -> int:
+    async def is_empty(self) -> bool:
         query = """
+        RETURN EXISTS {
         MATCH (n)
-        RETURN COUNT(n) as total_nodes;
+        } AS node_exists;
         """
         query_result = await self.query(query)
-        return query_result[0]["total_nodes"]
+        return not query_result[0]["node_exists"]
 
     @deadlock_retry()
     async def query(

cognee/modules/data/exceptions/__init__.py

@@ -9,5 +9,4 @@ from .exceptions import (
     UnauthorizedDataAccessError,
     DatasetNotFoundError,
     DatasetTypeError,
-    SearchOnEmptyGraphError,
 )

cognee/modules/data/exceptions/exceptions.py

@@ -35,16 +35,6 @@ class DatasetNotFoundError(CogneeValidationError):
         super().__init__(message, name, status_code)
 
 
-class SearchOnEmptyGraphError(CogneeValidationError):
-    def __init__(
-        self,
-        message: str = "Knowledge graph is empty, please ensure data is added and cognified.",
-        name: str = "SearchOnEmptyGraphError",
-        status_code=status.HTTP_400_BAD_REQUEST,
-    ):
-        super().__init__(message, name, status_code)
-
-
 class DatasetTypeError(CogneeValidationError):
     def __init__(
         self,

cognee/tests/test_kuzu.py

@@ -51,21 +51,21 @@ async def main():
 
         graph_engine = await get_graph_engine()
 
-        nodes_count = await graph_engine.count_nodes()
+        is_empty = await graph_engine.is_empty()
 
-        assert nodes_count == 0, "Kuzu graph database is not empty"
+        assert is_empty, "Kuzu graph database is not empty"
 
         await cognee.add([explanation_file_path_quantum], dataset_name)
 
-        nodes_count = await graph_engine.count_nodes()
+        is_empty = await graph_engine.is_empty()
 
-        assert nodes_count == 0, "Kuzu graph database should be empty before cognify"
+        assert is_empty, "Kuzu graph database should be empty before cognify"
 
         await cognee.cognify([dataset_name])
 
-        nodes_count = await graph_engine.count_nodes()
+        is_empty = await graph_engine.is_empty()
 
-        assert nodes_count != 0, "Kuzu graph database should not be empty"
+        assert not is_empty, "Kuzu graph database should not be empty"
 
         from cognee.infrastructure.databases.vector import get_vector_engine
 
@@ -131,9 +131,9 @@ async def main():
 
         await cognee.prune.prune_system(metadata=True)
 
-        nodes_count = await graph_engine.count_nodes()
+        is_empty = await graph_engine.is_empty()
 
-        assert nodes_count == 0, "Kuzu graph database is not empty"
+        assert is_empty, "Kuzu graph database is not empty"
 
     finally:
         # Ensure cleanup even if tests fail

cognee/tests/test_neo4j.py

@@ -39,9 +39,9 @@ async def main():
 
     graph_engine = await get_graph_engine()
 
-    nodes_count = await graph_engine.count_nodes()
+    is_empty = await graph_engine.is_empty()
 
-    assert nodes_count == 0, "Graph has to be empty"
+    assert is_empty, "Graph has to be empty"
 
     await cognee.add([explanation_file_path_nlp], dataset_name)
 
@@ -50,15 +50,15 @@ async def main():
     )
 
     await cognee.add([explanation_file_path_quantum], dataset_name)
-    nodes_count = await graph_engine.count_nodes()
+    is_empty = await graph_engine.is_empty()
 
-    assert nodes_count == 0, "Graph has to be empty before cognify"
+    assert is_empty, "Graph has to be empty before cognify"
 
     await cognee.cognify([dataset_name])
 
-    nodes_count = await graph_engine.count_nodes()
+    is_empty = await graph_engine.is_empty()
 
-    assert nodes_count != 0, "Graph shouldn't be empty"
+    assert not is_empty, "Graph shouldn't be empty"
 
     from cognee.infrastructure.databases.vector import get_vector_engine
 
@@ -132,8 +132,8 @@ async def main():
     assert not os.path.isdir(data_root_directory), "Local data files are not deleted"
 
     await cognee.prune.prune_system(metadata=True)
-    nodes_count = await graph_engine.count_nodes()
+    is_empty = await graph_engine.is_empty()
-    assert nodes_count == 0, "Neo4j graph database is not empty"
+    assert is_empty, "Neo4j graph database is not empty"
 
 
 if __name__ == "__main__":