kaxil commented on a change in pull request #5743: [AIRFLOW-5088][AIP-24] 
Persisting serialized DAG in DB for webserver scalability
URL: https://github.com/apache/airflow/pull/5743#discussion_r314041450
 
 

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 File path: airflow/models/serialized_dag.py
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 @@ -0,0 +1,155 @@
+# -*- coding: utf-8 -*-
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+"""Serialzed DAG table in database."""
+
+import hashlib
+from typing import Any, Dict, List, Optional, TYPE_CHECKING
+from sqlalchemy import Column, Index, Integer, String, Text, and_
+from sqlalchemy.sql import exists
+
+from airflow.models.base import Base, ID_LEN
+from airflow.utils import db, timezone
+from airflow.utils.sqlalchemy import UtcDateTime
+
+
+if TYPE_CHECKING:
+    from airflow.dag.serialization.serialized_dag import SerializedDAG  # 
noqa: F401, E501; # pylint: disable=cyclic-import
+    from airflow.models import DAG  # noqa: F401; # pylint: 
disable=cyclic-import
+
+
+class SerializedDagModel(Base):
+    """A table for serialized DAGs.
+
+    serialized_dag table is a snapshot of DAG files synchronized by scheduler.
+    This feature is controlled by:
+        [core] dagcached = False: enable this feature
+        [core] dagcached_min_update_interval = 30 (s):
+            serialized DAGs are updated in DB when a file gets processed by 
scheduler,
+            to reduce DB write rate, there is a minimal interval of updating 
serialized DAGs.
+        [scheduler] dag_dir_list_interval = 300 (s):
+            interval of deleting serialized DAGs in DB when the files are 
deleted, suggest
+            to use a smaller interval such as 60
 
 Review comment:
   Sorry didn't understand this one, what do you mean?

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