feat: optimize database query methods for improved performance and readability

lightrag/kg/postgres_impl.py

@@ -3100,114 +3100,93 @@ class PGGraphStorage(BaseGraphStorage):
         return result
 
     async def has_node(self, node_id: str) -> bool:
-        entity_name_label = self._normalize_node_id(node_id)
+        query = f"""
+            SELECT EXISTS (
+              SELECT 1
+              FROM {self.graph_name}.base
+              WHERE ag_catalog.agtype_access_operator(
+                      VARIADIC ARRAY[properties, '"entity_id"'::agtype]
+                    ) = (to_json($1::text)::text)::agtype
+              LIMIT 1
+            ) AS node_exists;
+        """
 
-        query = """SELECT * FROM cypher('%s', $$
-                     MATCH (n:base {entity_id: "%s"})
-                     RETURN count(n) > 0 AS node_exists
-                   $$) AS (node_exists bool)""" % (self.graph_name, entity_name_label)
-
-        single_result = (await self._query(query))[0]
-
-        return single_result["node_exists"]
+        params = {"node_id": node_id}
+        row = (await self._query(query, params=params))[0]
+        return bool(row["node_exists"])
 
     async def has_edge(self, source_node_id: str, target_node_id: str) -> bool:
-        src_label = self._normalize_node_id(source_node_id)
-        tgt_label = self._normalize_node_id(target_node_id)
-
-        query = """SELECT * FROM cypher('%s', $$
-                     MATCH (a:base {entity_id: "%s"})-[r]-(b:base {entity_id: "%s"})
-                     RETURN COUNT(r) > 0 AS edge_exists
-                   $$) AS (edge_exists bool)""" % (
-            self.graph_name,
-            src_label,
-            tgt_label,
-        )
-
-        single_result = (await self._query(query))[0]
-
-        return single_result["edge_exists"]
+        query = f"""
+            WITH a AS (
+              SELECT id AS vid
+              FROM {self.graph_name}.base
+              WHERE ag_catalog.agtype_access_operator(
+                      VARIADIC ARRAY[properties, '"entity_id"'::agtype]
+                    ) = (to_json($1::text)::text)::agtype
+            ),
+            b AS (
+              SELECT id AS vid
+              FROM {self.graph_name}.base
+              WHERE ag_catalog.agtype_access_operator(
+                      VARIADIC ARRAY[properties, '"entity_id"'::agtype]
+                    ) = (to_json($2::text)::text)::agtype
+            )
+            SELECT EXISTS (
+              SELECT 1
+              FROM {self.graph_name}."DIRECTED" d
+              JOIN a ON d.start_id = a.vid
+              JOIN b ON d.end_id   = b.vid
+              LIMIT 1
+            )
+            OR EXISTS (
+              SELECT 1
+              FROM {self.graph_name}."DIRECTED" d
+              JOIN a ON d.end_id   = a.vid
+              JOIN b ON d.start_id = b.vid
+              LIMIT 1
+            ) AS edge_exists;
+        """
+        params = {
+            "source_node_id": source_node_id,
+            "target_node_id": target_node_id,
+        }
+        row = (await self._query(query, params=params))[0]
+        return bool(row["edge_exists"])
 
     async def get_node(self, node_id: str) -> dict[str, str] | None:
         """Get node by its label identifier, return only node properties"""
 
         label = self._normalize_node_id(node_id)
-        query = """SELECT * FROM cypher('%s', $$
-                     MATCH (n:base {entity_id: "%s"})
-                     RETURN n
-                   $$) AS (n agtype)""" % (self.graph_name, label)
-        record = await self._query(query)
-        if record:
-            node = record[0]
-            node_dict = node["n"]["properties"]
 
-            # Process string result, parse it to JSON dictionary
-            if isinstance(node_dict, str):
-                try:
-                    node_dict = json.loads(node_dict)
-                except json.JSONDecodeError:
-                    logger.warning(
-                        f"[{self.workspace}] Failed to parse node string: {node_dict}"
-                    )
-
-            return node_dict
+        result = await self.get_nodes_batch(node_ids=[label])
+        if result and node_id in result:
+            return result[node_id]
         return None
 
     async def node_degree(self, node_id: str) -> int:
         label = self._normalize_node_id(node_id)
 
-        query = """SELECT * FROM cypher('%s', $$
-                     MATCH (n:base {entity_id: "%s"})-[r]-()
-                     RETURN count(r) AS total_edge_count
-                   $$) AS (total_edge_count integer)""" % (self.graph_name, label)
-        record = (await self._query(query))[0]
-        if record:
-            edge_count = int(record["total_edge_count"])
-            return edge_count
+        result = await self.node_degrees_batch(node_ids=[label])
+        if result and node_id in result:
+            return result[node_id]
 
     async def edge_degree(self, src_id: str, tgt_id: str) -> int:
-        src_degree = await self.node_degree(src_id)
-        trg_degree = await self.node_degree(tgt_id)
 
-        # Convert None to 0 for addition
-        src_degree = 0 if src_degree is None else src_degree
-        trg_degree = 0 if trg_degree is None else trg_degree
-
-        degrees = int(src_degree) + int(trg_degree)
-
-        return degrees
+        result = await self.edge_degrees_batch(edges=[(src_id, tgt_id)])
+        if result and (src_id, tgt_id) in result:
+            return result[(src_id, tgt_id)]
 
     async def get_edge(
         self, source_node_id: str, target_node_id: str
     ) -> dict[str, str] | None:
         """Get edge properties between two nodes"""
-
         src_label = self._normalize_node_id(source_node_id)
         tgt_label = self._normalize_node_id(target_node_id)
 
-        query = """SELECT * FROM cypher('%s', $$
-                     MATCH (a:base {entity_id: "%s"})-[r]-(b:base {entity_id: "%s"})
-                     RETURN properties(r) as edge_properties
-                     LIMIT 1
-                   $$) AS (edge_properties agtype)""" % (
-            self.graph_name,
-            src_label,
-            tgt_label,
-        )
-        record = await self._query(query)
-        if record and record[0] and record[0]["edge_properties"]:
-            result = record[0]["edge_properties"]
-
-            # Process string result, parse it to JSON dictionary
-            if isinstance(result, str):
-                try:
-                    result = json.loads(result)
-                except json.JSONDecodeError:
-                    logger.warning(
-                        f"[{self.workspace}] Failed to parse edge string: {result}"
-                    )
-
-            return result
+        result = await self.get_edges_batch([{"src": src_label, "tgt": tgt_label}])
+        if result and (src_label, tgt_label) in result:
+            return result[(src_label, tgt_label)]
+        return None
 
     async def get_node_edges(self, source_node_id: str) -> list[tuple[str, str]] | None:
         """