Use thread_id for partition key, ignore tasks for stale checkpoints

libs/checkpoint-postgres/langgraph/checkpoint/postgres/aio.py

@@ -298,18 +298,16 @@ class AsyncPostgresSaver(BasePostgresSaver):
             if all(w[0] in WRITES_IDX_MAP for w in writes)
             else self.INSERT_CHECKPOINT_WRITES_SQL
         )
+        params = await asyncio.to_thread(
+            self._dump_writes,
+            config["configurable"]["thread_id"],
+            config["configurable"]["checkpoint_ns"],
+            config["configurable"]["checkpoint_id"],
+            task_id,
+            writes,
+        )
         async with self._cursor(pipeline=True) as cur:
-            await cur.executemany(
-                query,
-                await asyncio.to_thread(
-                    self._dump_writes,
-                    config["configurable"]["thread_id"],
-                    config["configurable"]["checkpoint_ns"],
-                    config["configurable"]["checkpoint_id"],
-                    task_id,
-                    writes,
-                ),
-            )
+            await cur.executemany(query, params)
 
     @asynccontextmanager
     async def _cursor(self, *, pipeline: bool = False) -> AsyncIterator[AsyncCursor]: