气流depends_on_past说明 [英] Airflow depends_on_past explanation

问题描述

根据官方气流文档，
任务上游的任务实例必须处于成功状态。另外，如果您设置了depends_on_past = True，则前一个任务实例需要成功（除非是该任务的第一次运行）。

According to the official Airflow docs, The task instances directly upstream from the task need to be in a success state. Also, if you have set depends_on_past=True, the previous task instance needs to have succeeded (except if it is the first run for that task).

众所周知，任务是实例化和

As all know, the task is kind of 'instantiated & parameteriazed' operator.

现在这让我感到困惑。例如：

Now this is what confuse me. For example:

DAG: {op_1} -> {op_2} -> {op_3}

{op_2}是一个简单的PythonOperator，它从{op_1}中获取1个参数并执行操作;

{op_2} is a simple PythonOperator that takes 1 parameter from {op_1} and do stuff;

据我所知，op_2（param_1）& op_2（param_2）被视为2个不同的任务。

To my understanding, op_2(param_1) & op_2(param_2) are considered as 2 different tasks.

将 depends_on_past 设置为True，然后：

Given depends_on_past is set to True, then:

1. 如果op_2（param_1）仍在运行；可以运行op_2（param_2）吗？


2. 如果op_2（param_1）在上一次运行中失败；可以在当前运行中运行op_2（param_1）吗？

推荐答案

从官方文档：

depends_on_past （布尔值）设置为True时，如果先前的任务计划未成功，则不会触发任务。

depends_on_past (boolean) when set to True, keeps a task from getting triggered if the previous schedule for the task hasn’t succeeded.

因此，除非先前运行的DAG运行失败，否则 depends_on_past 不应是一个因素，如果先前运行了DAG，则根本不会影响当前运行运行成功执行任务。

So unless a previous run of your DAG has failed, the depends_on_past should not be a factor, it will not affect the current run at all if the previous run executed the tasks successfully.

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