kaxil commented on a change in pull request #9850:
URL: https://github.com/apache/airflow/pull/9850#discussion_r455714688
##########
File path: airflow/models/serialized_dag.py
##########
@@ -94,13 +97,26 @@ def write_dag(cls, dag: DAG, min_update_interval:
Optional[int] = None, session=
(timezone.utcnow() -
timedelta(seconds=min_update_interval)) < cls.last_updated))
).scalar():
return
- log.debug("Writing DAG: %s to the DB", dag.dag_id)
- session.merge(cls(dag))
+
+ log.debug("Checking if DAG (%s) is updated or same", dag.dag_id)
+ serialized_dag_from_db: SerializedDagModel = (
+ session
+ .query(cls)
+ .filter(cls.dag_id == dag.dag_id)
+ .one_or_none()
+ )
Review comment:
`get` will only provide performance boost if the object is in memory
isn't it?
Otherwise under the hood, get calls `one` which in turn calls `one_or_none`:
https://github.com/sqlalchemy/sqlalchemy/blob/f4aa9def8f35136d1fe3bba81aaeddb72e7772a2/lib/sqlalchemy/orm/query.py#L907
https://github.com/sqlalchemy/sqlalchemy/blob/rel_1_3_17/lib/sqlalchemy/orm/loading.py#L287
https://github.com/sqlalchemy/sqlalchemy/blob/f4aa9def8f35136d1fe3bba81aaeddb72e7772a2/lib/sqlalchemy/orm/query.py#L2641-L2659
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