ashb commented on code in PR #74274: URL: https://github.com/apache/airflow/pull/74274#discussion_r4197402190
########## airflow-core/docs/authoring-and-scheduling/loops-and-mapped-tasks.rst: ########## @@ -0,0 +1,61 @@ + .. 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. + +.. _loops-and-mapped-tasks: + +====================== +Loops and mapped tasks +====================== + +A Dag does not have to be static. How much work it does can depend on data that only exists at +runtime: how many files arrived, what the previous step found, or whether an answer is good enough +yet. Airflow has two features for this, and sometimes neither is what you need. + +Choose a mechanism +================== + +.. list-table:: + :header-rows: 1 + :widths: 30 30 40 + + * - You want to + - Use + - How it works + * - Run the same task once for each item in a collection + - :ref:`Mapped tasks <mapped-tasks>` + - ``task.expand(...)`` creates one task instance per item once the collection is known. The + instances can run concurrently. + * - Repeat a group of tasks, each pass building on the result of the previous one, until a + condition is met + - :ref:`Loops <loops>` + - ``task_group.loop(...)`` creates the next pass of task instances only if the last pass says Review Comment: Yes, agreed. I started with loop but changed it to iteration half way through the design. -- 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]
