dag是一种数据存储结构，从它被发明的30多年来一直都有人使用，本身并没有问题。但它和区块链的区别在于dag没有传统意义上的共识，每笔交易的可信与否取决于相信这笔交易的人数。 所以采用dag技术的核心问题在于如何保护全网达成的一致。

不是说分布式系统的计算要用 dag 来实现，而是数据的处理流程本来就是这样的，我们抽象了一下，发现可以他总是可以描述为一个 dag。 早期只有 MapReduce 的时候，Hive 就是把一个计算任务分解成若干级联的 Map-Reduce ，后来大家发现这种模型太低效，把没有的 ...

这个过程称为dag的线性化过程，也称为dag的拓扑排序，这里的排序并不是指大小上的有序，而是指时间上的有序。因有可能子流程间不存在时间上的依赖性，如上图的2和3以及4和5节点，不存在相互的依赖，所以dag的拓扑排序并不只有一种可能。如下图中的所有 ...

2020年4月30日 · ### In parent_dag.py ### from airflow.operators.trigger_dagrun import TriggerDagRunOperator # changed import from airflow.utils.trigger_rule import TriggerRule with airflow.operators.empty import EmptyOperator parent_dag = DAG( dag_id="parent_dag_id", schedule_interval= None ) with parent_dag: # An arbitrary task in your parent DAG started ...

2017年1月23日 · Backfilling is done to run DAG explicitly to test/manually run DAG/re run a DAG which error-ed out. You do this using CLI. airflow backfill -s <<start_date>> <<dag>> #optionally provide -1 as start_date to run it immediately start_date is, as the name suggests, date from when the DAG definition is valid

Specifically, it ensures that unmanaged resources -in this case implementations of the DAG class- are properly cleaned up, even if there are exceptions thrown (without needing to use a try/except block every time.) Additionally it's nice to not have to add dag=dag to every single one.

2010年1月10日 · I would like to find all the dag runs for a specific dag for a specific execution date. As I read on the documentation there is this function: dag_runs = DagRun.find(dag_id=self.dag_name, execution_date=datetime.now()) The problem with this is that the time needs to be exactly the same as well.

2018年8月7日 · I have the following DAG with 3 tasks: start --&gt; special_task --&gt; end The task in the middle can succeed or fail, but end must always be executed (imagine this is a task for cleanly closing

2016年4月5日 · I have a large directed acyclic graph that I would like to visualize in a bitmap image. Ideally I'd like to have all the root nodes at the top of the image, and all of the leaf nodes at the bottom...

2020年9月6日 · The PythonOperator op_args parameter is templatized.. The callable only writes the latest execution date to a file so you can implement the function the following way: