dstandish commented on code in PR #43477: URL: https://github.com/apache/airflow/pull/43477#discussion_r1821526483
########## docs/apache-airflow/core-concepts/backfill.rst: ########## @@ -0,0 +1,69 @@ + .. 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. + +Backfill +======== + +Backfill is when you create runs for past dates of a dag. Airflow provides a mechanism +to do this through the CLI and REST API. You provide a dag, a start date, and an end date, +and airflow will create runs in the range according to the dag's schedule. + +Backfill does not make sense for dags that don't have a time-based schedule. + +Control over data reprocessing +------------------------------ + +There are three options for reprocessing behavior: + +* **none** - if there's already a run for this logical date, do not create another, no matter the state +* **failed** - if a run exists, if the state is failed, create a new run for this date +* **completed** - if a run exists, if the state is completed or failed, create a new run for this date + +If the latest run is still running or is queued, we do not create another run, no matter the chosen reprocessing behavior. + +Concurrency control +------------------- + +You can set ``max_active_runs`` on a backfill and it will control how many dag runs in +the backfill can run concurrently. Backfill ``max_active_runs`` is applied independently +the DAG ``max_active_runs`` setting. + +Run ordering +------------ + +You can run your backfill in reverse, i.e. latest runs first. The CLI option is ``--run-backwards``. + +Dry run +------- + +Backfill dry run is a CLI option that will print out the dates that the +backfill will consider creating runs for. Whether or not they will be created +depends on your chosen reprocessing behavior and the states of any existing +runs in the range at the time you actually run the backfill. + +Example: +-------- + +.. code-block:: bash + + airflow backfill create --dag tutorial \ Review Comment: done in the followup pr https://github.com/apache/airflow/pull/43478 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
