Running Child Pipeline if Parent Pipeline is Successful

[bjadav]

I have a child pipeline which depends on successful execution of other parent pipeline. In parent pipeline, I am updating some MySQL tables from external source. Then in child pipeline, this updated MySQL tables are used in custom SQL query. I need to ensure that before running this custom query in child pipeline, parent pipeline has properly updated the tables in MySQL DB and it didn’t failed hence before running child pipeline I need to know if the parent pipeline was executed successfully or not. How do I achieve this?

[tlikarish · Accepted solution]

Here’s an example project of what I was thinking of. In this project, there is a parent pipeline with 3 Pipeline Execute snaps. Each Pipeline Execute will execute child pipelines: step 1, step 2, and step 3. The parent will execute step 1, but step 2 is designed to fail. Notice that since it failed, the Pipeline Execute called step 3 is not executed. Is this a helpful example of what I had proposed?

projects_exe-on-success.zip (3.5 KB)

[bjadav]

@tlikarish Thank you for the example! It is working as expected. The only thing I need to make sure is that there are not open input or output in the child pipelines

[bjadav]

@tlikarish for this to work, we need to have no open inputs or output in pipeline. But there are snaps which do not have optional input/ouput. In such case do you know of the dummy snap that I can use to close of the open output of the snap in a pipeline?
Currently, I am using MySQL Execute snap with SQL statement as SELECT 1; but this is not efficient as this still makes connection to a database hence I am looking to replace this with some dummy snap to close of the output.

[shubhisharma]

Why don’t you try using conditional or router snap to check if the execution was successful? You can check on some parameter basically, which comes as (success)output from your first operation and then you can use pipeline execute to invoke your child pipeline.

[tlikarish]

Some snaps you’re able to remove the output view, but not all of them. If you’re not able to remove the output view, then one way to work around that would be to use the Exit snap.

If the upstream snaps have no expected output, then you could use an Exit snap with the threshold set to 0.

If there is output and you’d like to ignore it, then you could use a Head snap in front of the Exit to limit the output to 1 and set the threshold to 1 on the Exit. Something like this: